You are a medical exam question writer. Your task is to search the medical textbook library database and then generate 100 high-quality MCQs for an MBBS Final exam, referencing Moore's Clinically Oriented Anatomy, 7th edition. ## Step 1: Search the Library Use query_library_db to find Moore's Clinically Oriented Anatomy. First run: ```sql SELECT isbn, title, speciality, file_path FROM v_book_overview WHERE title LIKE '%Moore%' OR title LIKE '%Clinically Oriented Anatomy%' LIMIT 5 ``` Then search for content in these topic areas using paragraphs_fts and headings_fts. Run multiple searches: Search 1 - Axilla vessels: ```sql SELECT book_title, section_heading, '/textbooks/' || block_file_path AS file_path, line_start, line_end, snippet(paragraphs_fts, 0, '>>>', '<<<', '...', 40) as snippet FROM paragraphs_fts WHERE paragraphs_fts MATCH 'axillary artery branches' ORDER BY rank LIMIT 5 ``` Search 2 - Arm vessels: ```sql SELECT book_title, section_heading, '/textbooks/' || block_file_path AS file_path, line_start, line_end, snippet(paragraphs_fts, 0, '>>>', '<<<', '...', 40) as snippet FROM paragraphs_fts WHERE paragraphs_fts MATCH 'brachial artery forearm radial ulnar' ORDER BY rank LIMIT 5 ``` Search 3 - Venous drainage upper limb: ```sql SELECT book_title, section_heading, '/textbooks/' || block_file_path AS file_path, line_start, line_end, snippet(paragraphs_fts, 0, '>>>', '<<<', '...', 40) as snippet FROM paragraphs_fts WHERE paragraphs_fts MATCH 'cephalic basilic vein upper limb lymph' ORDER BY rank LIMIT 5 ``` Search 4 - Pelvic vessels: ```sql SELECT book_title, section_heading, '/textbooks/' || block_file_path AS file_path, line_start, line_end, snippet(paragraphs_fts, 0, '>>>', '<<<', '...', 40) as snippet FROM paragraphs_fts WHERE paragraphs_fts MATCH 'internal iliac artery pelvis branches' ORDER BY rank LIMIT 5 ``` Search 5 - Gluteal/thigh/leg vessels: ```sql SELECT book_title, section_heading, '/textbooks/' || block_file_path AS file_path, line_start, line_end, snippet(paragraphs_fts, 0, '>>>', '<<<', '...', 40) as snippet FROM paragraphs_fts WHERE paragraphs_fts MATCH 'femoral artery profunda popliteal tibial' ORDER BY rank LIMIT 5 ``` Search 6 - Fetal circulation: ```sql SELECT book_title, section_heading, '/textbooks/' || block_file_path AS file_path, line_start, line_end, snippet(paragraphs_fts, 0, '>>>', '<<<', '...', 40) as snippet FROM paragraphs_fts WHERE paragraphs_fts MATCH 'fetal circulation foramen ovale ductus arteriosus' ORDER BY rank LIMIT 5 ``` Search 7 - Heart development: ```sql SELECT book_title, section_heading, '/textbooks/' || block_file_path AS file_path, line_start, line_end, snippet(paragraphs_fts, 0, '>>>', '<<<', '...', 40) as snippet FROM paragraphs_fts WHERE paragraphs_fts MATCH 'development heart great vessels cardiac anomaly' ORDER BY rank LIMIT 5 ``` Search 8 - Cardiovascular anomalies: ```sql SELECT book_title, section_heading, '/textbooks/' || block_file_path AS file_path, line_start, line_end, snippet(paragraphs_fts, 0, '>>>', '<<<', '...', 40) as snippet FROM paragraphs_fts WHERE paragraphs_fts MATCH 'ventricular septal defect atrial tetralogy fallot' ORDER BY rank LIMIT 5 ``` Search 9 - Respiratory development: ```sql SELECT book_title, section_heading, '/textbooks/' || block_file_path AS file_path, line_start, line_end, snippet(paragraphs_fts, 0, '>>>', '<<<', '...', 40) as snippet FROM paragraphs_fts WHERE paragraphs_fts MATCH 'tracheoesophageal fistula larynx trachea development' ORDER BY rank LIMIT 5 ``` Search 10 - Nasal sinuses and lungs: ```sql SELECT book_title, section_heading, '/textbooks/' || block_file_path AS file_path, line_start, line_end, snippet(paragraphs_fts, 0, '>>>', '<<<', '...', 40) as snippet FROM paragraphs_fts WHERE paragraphs_fts MATCH 'paranasal sinuses nasal cavity pleura lung' ORDER BY rank LIMIT 5 ``` Also search headings: ```sql SELECT title, book_title, '/textbooks/' || block_file_path AS file_path, line_number, para_line_ranges FROM headings_fts WHERE headings_fts MATCH 'axillary vessels arm forearm' ORDER BY rank LIMIT 8 ``` ```sql SELECT title, book_title, '/textbooks/' || block_file_path AS file_path, line_number, para_line_ranges FROM headings_fts WHERE headings_fts MATCH 'fetal circulation cardiovascular development' ORDER BY rank LIMIT 8 ``` ```sql SELECT title, book_title, '/textbooks/' || block_file_path AS file_path, line_number, para_line_ranges FROM headings_fts WHERE headings_fts MATCH 'recurrent laryngeal nerve lymphatic drainage head neck' ORDER BY rank LIMIT 8 ``` After running all searches, read 2-3 of the most relevant file sections using read_file to get actual content details. ## Step 2: Generate 100 MCQs Based on the content found (supplemented by your knowledge of Moore's COA 7th edition), generate exactly 100 MCQs distributed across these topics: - Topic A: Vessels of Axilla, Arm, Forearm, Hand; Venous Drainage & Lymphatics of Upper Limb; Clinical Problems (Questions 1-15) - Topic B: Vessels of Pelvis; Vessels of Back (Questions 16-25) - Topic C: Vasculature of Gluteal Region, Thigh, Leg, and Foot (Questions 26-38) - Topic D: Development of Cardiovascular System - Fetal & Neonatal Circulation; Fate of Fetal Vascular Structures; Development of Heart & Great Vessels (Questions 39-55) - Topic E: Developmental Anomalies of Heart & Great Vessels; Development of Fetal Arteries & Veins (Questions 56-68) - Topic F: Respiratory System - Nasal Cavities & Paranasal Sinuses (Questions 69-76) - Topic G: Larynx, Trachea; Lymphatic Drainage of Head & Neck; Injury to Recurrent Laryngeal Nerves; Clinical Problems; Tracheo-Esophageal Fistula (Questions 77-88) - Topic H: Pleurae, Lungs, Tracheobronchial Tree; Development of Respiratory System (Questions 89-100) ## Format for each question: **Q[number]. [Question stem]** A. [Option] B. [Option] C. [Option] D. [Option] **Answer: [Letter]. [Brief explanation (2-3 sentences referencing Moore's COA 7th ed)]** --- ## Requirements: - Mix of theoretical anatomy and clinical scenario questions (about 50/50) - Clinical questions should present a patient scenario then ask about anatomy/clinical correlation - Questions should be at appropriate MBBS Final exam difficulty - All 4 options should be plausible (no obviously wrong distractors) - Answers must be accurate per Moore's Clinically Oriented Anatomy 7th edition - Cover all sub-topics within each section - Include questions on: surgical/clinical relevance, anatomical relationships, nerve/vessel injuries, developmental defects with clinical presentations Return the complete 100 MCQs with answers as your final output. Do not truncate.

ls /home/daytona/workspace/ 2>/dev/null || echo "workspace is empty or does not …

mkdir -p /home/daytona/workspace/mcq-exam && python3 -c "from reportlab.lib.page…

~/mcq-exam/generate_mcq_pdf.py

from reportlab.lib.pagesizes import A4
from reportlab.lib.styles import getSampleStyleSheet, ParagraphStyle
from reportlab.lib.units import cm
from reportlab.lib import colors
from reportlab.platypus import (
    SimpleDocTemplate, Paragraph, Spacer, HRFlowable,
    KeepTogether, Table, TableStyle, PageBreak
)
from reportlab.lib.enums import TA_LEFT, TA_CENTER, TA_JUSTIFY

OUTPUT = "/home/daytona/workspace/mcq-exam/Moore_COA_100_MCQs.pdf"

# ── colour palette ──────────────────────────────────────────────────────────
DARK_BLUE   = colors.HexColor("#1A3A5C")
MID_BLUE    = colors.HexColor("#2E6DA4")
LIGHT_BLUE  = colors.HexColor("#D6E8F7")
ACCENT      = colors.HexColor("#C0392B")
ANSWER_BG   = colors.HexColor("#EAF4EA")
ANSWER_BORDER = colors.HexColor("#27AE60")
GREY_LINE   = colors.HexColor("#CCCCCC")
WHITE       = colors.white
BLACK       = colors.black

# ── styles ───────────────────────────────────────────────────────────────────
styles = getSampleStyleSheet()

title_style = ParagraphStyle(
    "DocTitle", parent=styles["Title"],
    fontSize=22, textColor=WHITE, alignment=TA_CENTER,
    spaceAfter=4, spaceBefore=0, leading=28,
    fontName="Helvetica-Bold"
)
subtitle_style = ParagraphStyle(
    "DocSubtitle", parent=styles["Normal"],
    fontSize=11, textColor=LIGHT_BLUE, alignment=TA_CENTER,
    spaceAfter=2, fontName="Helvetica"
)
meta_style = ParagraphStyle(
    "DocMeta", parent=styles["Normal"],
    fontSize=9, textColor=LIGHT_BLUE, alignment=TA_CENTER,
    spaceAfter=0, fontName="Helvetica"
)
section_style = ParagraphStyle(
    "Section", parent=styles["Normal"],
    fontSize=13, textColor=WHITE, fontName="Helvetica-Bold",
    spaceBefore=14, spaceAfter=6, leading=18, leftIndent=0
)
q_num_style = ParagraphStyle(
    "QNum", parent=styles["Normal"],
    fontSize=10, textColor=MID_BLUE, fontName="Helvetica-Bold",
    spaceBefore=0, spaceAfter=0
)
q_text_style = ParagraphStyle(
    "QText", parent=styles["Normal"],
    fontSize=10.5, textColor=BLACK, fontName="Helvetica-Bold",
    spaceBefore=0, spaceAfter=4, leading=15
)
option_style = ParagraphStyle(
    "Option", parent=styles["Normal"],
    fontSize=10, textColor=colors.HexColor("#222222"),
    fontName="Helvetica", leading=14,
    leftIndent=14, spaceBefore=1, spaceAfter=1
)
answer_label_style = ParagraphStyle(
    "AnsLabel", parent=styles["Normal"],
    fontSize=9.5, textColor=ANSWER_BORDER, fontName="Helvetica-Bold",
    spaceBefore=4, spaceAfter=1
)
answer_text_style = ParagraphStyle(
    "AnsText", parent=styles["Normal"],
    fontSize=9, textColor=colors.HexColor("#1A1A1A"),
    fontName="Helvetica", leading=13, alignment=TA_JUSTIFY,
    spaceBefore=0, spaceAfter=6
)

# ── helpers ──────────────────────────────────────────────────────────────────

def section_block(letter, title, q_range):
    """Returns a blue banner for a section heading."""
    label = f"SECTION {letter}  |  {title}  (Q{q_range})"
    tbl = Table([[Paragraph(label, section_style)]], colWidths=[17*cm])
    tbl.setStyle(TableStyle([
        ("BACKGROUND", (0,0), (-1,-1), DARK_BLUE),
        ("ROUNDEDCORNERS", [4,4,4,4]),
        ("TOPPADDING", (0,0), (-1,-1), 7),
        ("BOTTOMPADDING", (0,0), (-1,-1), 7),
        ("LEFTPADDING", (0,0), (-1,-1), 10),
    ]))
    return tbl

def question_block(num, stem, options, answer_letter, explanation):
    """Returns a KeepTogether block for one MCQ."""
    elems = []

    # Question number + stem
    q_header = Paragraph(f"Q{num}.", q_num_style)
    q_body   = Paragraph(stem, q_text_style)

    # Options
    opt_paras = []
    letters = ["A", "B", "C", "D"]
    for i, opt in enumerate(options):
        opt_paras.append(Paragraph(f"<b>{letters[i]}.</b>  {opt}", option_style))

    # Answer box
    ans_label = Paragraph(f"✔  Answer: {answer_letter}", answer_label_style)
    ans_text  = Paragraph(explanation, answer_text_style)
    ans_tbl   = Table(
        [[ans_label], [ans_text]],
        colWidths=[16.4*cm]
    )
    ans_tbl.setStyle(TableStyle([
        ("BACKGROUND",    (0,0), (-1,-1), ANSWER_BG),
        ("LINEAFTER",     (0,0), (0,-1),  0.5, ANSWER_BORDER),
        ("LINEBEFORE",    (0,0), (0,-1),  3,   ANSWER_BORDER),
        ("LINEBELOW",     (0,-1),(-1,-1), 0.5, ANSWER_BORDER),
        ("LINEABOVE",     (0,0), (-1,0),  0.5, ANSWER_BORDER),
        ("TOPPADDING",    (0,0), (-1,-1), 5),
        ("BOTTOMPADDING", (0,0), (-1,-1), 5),
        ("LEFTPADDING",   (0,0), (-1,-1), 8),
        ("RIGHTPADDING",  (0,0), (-1,-1), 6),
    ]))

    block = [q_header, q_body] + opt_paras + [Spacer(1,4), ans_tbl, Spacer(1,8),
             HRFlowable(width="100%", thickness=0.4, color=GREY_LINE)]
    return KeepTogether(block)

# ── ALL 100 questions ─────────────────────────────────────────────────────────
# Format: (num, stem, [optA, optB, optC, optD], answer_letter, explanation)

questions = [
# ─── SECTION A ───────────────────────────────────────────────────────────────
(1,
 "The axillary artery is divided into three parts by which structure?",
 ["Pectoralis minor muscle",
  "Pectoralis major muscle",
  "Coracobrachialis muscle",
  "Subclavius muscle"],
 "A",
 "Pectoralis minor divides the axillary artery into three parts: Part 1 medial, Part 2 posterior, Part 3 lateral. Part 1 = 1 branch, Part 2 = 2 branches, Part 3 = 3 branches (mnemonic: 1-2-3)."),

(2,
 "Which branch of the axillary artery accompanies the thoracodorsal nerve to supply latissimus dorsi?",
 ["Lateral thoracic artery",
  "Subscapular artery – thoracodorsal branch",
  "Anterior circumflex humeral artery",
  "Supreme thoracic artery"],
 "B",
 "The subscapular artery (Part 3) divides into the circumflex scapular artery and thoracodorsal artery. The thoracodorsal artery travels with the thoracodorsal nerve to supply latissimus dorsi – relevant in axillary clearance surgery."),

(3,
 "A 45-year-old woman undergoes mastectomy with axillary lymph node clearance. Post-operatively she develops lymphedema of the arm. Which group of axillary lymph nodes, when damaged, is most responsible?",
 ["Anterior (pectoral) nodes",
  "Posterior (subscapular) nodes",
  "Apical (infraclavicular) nodes",
  "Central nodes"],
 "C",
 "The apical (Level III) nodes are the final common pathway for all lymph from the upper limb. Damage during axillary clearance obstructs drainage causing arm lymphedema. All other groups ultimately drain into the apical nodes before reaching the subclavian lymph trunk."),

(4,
 "The brachial artery bifurcates into radial and ulnar arteries at which level?",
 ["Level of the surgical neck of humerus",
  "Neck of the radius, in the cubital fossa",
  "Mid-forearm",
  "Just below the medial epicondyle"],
 "B",
 "The brachial artery bifurcates at the neck of the radius within the cubital fossa, approximately 1 cm distal to the elbow crease. This is the standard site for blood pressure measurement and is at risk in supracondylar fractures."),

(5,
 "A child presents with a supracondylar fracture of the humerus. The distal pulse is absent and the hand is pale. Which artery is most likely compromised?",
 ["Radial artery at the wrist",
  "Brachial artery in the antecubital fossa",
  "Anterior interosseous artery",
  "Ulnar artery at Guyon's canal"],
 "B",
 "The brachial artery lies anterior to the humerus in the cubital fossa and is directly at risk in supracondylar fractures. The displaced distal fragment can kink or lacerate it, leading to Volkmann's ischemic contracture if not promptly treated."),

(6,
 "The radial artery pulse at the wrist is palpated lateral to which tendon?",
 ["Flexor carpi ulnaris",
  "Palmaris longus",
  "Flexor carpi radialis",
  "Flexor pollicis longus"],
 "C",
 "The radial artery runs just lateral to the flexor carpi radialis tendon at the wrist. This is the standard site for pulse assessment, arterial blood gas sampling, and arterial line cannulation."),

(7,
 "Which of the following correctly describes the superficial palmar arch?",
 ["Formed mainly by the radial artery, completed by the superficial branch of ulnar",
  "Formed mainly by the ulnar artery, completed by the superficial palmar branch of radial",
  "Formed entirely by the ulnar artery",
  "Formed entirely by the radial artery"],
 "B",
 "The superficial palmar arch lies deep to the palmar aponeurosis. It is formed mainly by the ulnar artery, completed laterally by the superficial palmar branch of the radial artery. It gives rise to common palmar digital arteries."),

(8,
 "The deep palmar arch is primarily formed by which artery?",
 ["Ulnar artery",
  "Radial artery",
  "Anterior interosseous artery",
  "Princeps pollicis artery"],
 "B",
 "The deep palmar arch lies on the metacarpal bases and interossei and is formed primarily by the radial artery (entering the palm through the 1st dorsal interosseous space), completed by the deep branch of the ulnar artery."),

(9,
 "During IV cannulation at the cubital fossa, which vein is most commonly used?",
 ["Cephalic vein – lateral to biceps tendon",
  "Median cubital vein – crosses the cubital fossa obliquely",
  "Basilic vein – medial to biceps tendon",
  "Brachial vein – deep to bicipital aponeurosis"],
 "B",
 "The median cubital vein crosses the cubital fossa obliquely connecting the cephalic and basilic veins. It is preferred for venepuncture because it is large, superficial, and relatively fixed. The bicipital aponeurosis separates it from the brachial artery below."),

(10,
 "A patient has a wrist laceration affecting structures within Guyon's canal. What passes through Guyon's canal?",
 ["Flexor carpi ulnaris tendon",
  "Median nerve",
  "Ulnar nerve and ulnar artery only",
  "Palmar cutaneous branch of ulnar nerve"],
 "C",
 "Guyon's canal (ulnar canal) transmits only the ulnar nerve and ulnar artery. The flexor carpi ulnaris inserts into the pisiform just proximal to the canal. The palmar cutaneous branch of the ulnar nerve arises proximal to the canal."),

(11,
 "The cephalic vein drains into which vessel?",
 ["Subclavian vein directly",
  "Axillary vein in the deltopectoral groove",
  "External jugular vein",
  "Brachiocephalic vein"],
 "B",
 "The cephalic vein travels in the deltopectoral groove between deltoid and pectoralis major and drains into the axillary vein just below the clavicle. This relationship is important in transvenous pacemaker insertion via the cephalic cutdown approach."),

(12,
 "Which lymph nodes receive lymph from the lateral (thumb) side of the hand and forearm?",
 ["Infraclavicular nodes directly",
  "Lateral axillary nodes via cephalic vein lymphatics",
  "Cubital (supratrochlear) nodes",
  "Central axillary nodes"],
 "B",
 "Lymph from the lateral side of the hand and forearm follows the cephalic vein and drains to infraclavicular or lateral axillary nodes. The cubital/supratrochlear nodes drain the medial (ulnar) side of the forearm and hand."),

(13,
 "A 35-year-old man sustains a knife injury to the medial aspect of the elbow. He notices a small tender node just above the elbow. What is this node and what area does it drain?",
 ["Lateral axillary node – drains the whole upper limb",
  "Supratrochlear (cubital) node – drains the medial forearm and hand (ulnar 3.5 digits)",
  "Central axillary node – drains the breast",
  "Anterior axillary node – drains the pectoral region"],
 "B",
 "The supratrochlear (cubital) node lies just above the medial epicondyle alongside the basilic vein. It drains the medial forearm, the ulnar side of the hand, and the little and ring fingers. Enlargement after a medial hand infection is a useful diagnostic sign."),

(14,
 "The anterior circumflex humeral artery primarily supplies which structure?",
 ["Long head of biceps",
  "Head of humerus and glenohumeral joint",
  "Deltoid muscle",
  "Coracobrachialis"],
 "B",
 "The anterior circumflex humeral artery (Part 3) winds around the surgical neck and primarily supplies the humeral head and glenohumeral joint. Avascular necrosis of the humeral head can occur when it is disrupted in fractures of the surgical neck."),

(15,
 "Which is the largest branch of the axillary artery and at what part does it arise?",
 ["Lateral thoracic – Part 2",
  "Subscapular artery – Part 3",
  "Thoracoacromial artery – Part 2",
  "Anterior circumflex humeral – Part 3"],
 "B",
 "The subscapular artery is the largest branch of the axillary artery, arising from Part 3. It divides into the circumflex scapular and thoracodorsal arteries. The anastomotic network around the scapula is an important collateral pathway in subclavian artery occlusion."),

# ─── SECTION B ───────────────────────────────────────────────────────────────
(16,
 "Which of the following is a branch of the POSTERIOR division of the internal iliac artery?",
 ["Uterine artery",
  "Obturator artery",
  "Superior gluteal artery",
  "Internal pudendal artery"],
 "C",
 "The posterior division gives three branches: iliolumbar, lateral sacral, and superior gluteal arteries. The anterior division supplies pelvic viscera and perineum (internal pudendal, inferior gluteal, uterine, obturator, umbilical, inferior vesical, middle rectal arteries)."),

(17,
 "A 28-year-old woman develops severe postpartum haemorrhage. The surgeon ligates both internal iliac arteries. Why does this control bleeding without causing lower limb ischemia?",
 ["Collateral flow from femoral artery branches",
  "Anastomoses between lumbar, iliolumbar, and lateral sacral arteries reconstitute pelvic flow",
  "Obturator artery provides sufficient collateral",
  "Gonadal arteries compensate"],
 "B",
 "Bilateral internal iliac ligation reduces pelvic pulse pressure by ~85%. Collateral flow is re-established via anastomoses between lumbar arteries (aorta) with iliolumbar, and median sacral with lateral sacral arteries. Lower limbs are unaffected because they are supplied by the external iliac/femoral system."),

(18,
 "The ureter is at greatest risk of injury during ligation of which pelvic vessel?",
 ["External iliac artery",
  "Internal pudendal artery",
  "Uterine artery (where it crosses the ureter)",
  "Inferior vesical artery"],
 "C",
 "The uterine artery crosses superior to the ureter ('water under the bridge') approximately 2 cm lateral to the cervix. This is the classic site of inadvertent ureteric ligation during hysterectomy – one of the most common serious complications of the procedure."),

(19,
 "Which artery supplies the superior part of the rectum and is a continuation of the inferior mesenteric artery?",
 ["Middle rectal artery",
  "Inferior rectal artery",
  "Superior rectal artery",
  "Median sacral artery"],
 "C",
 "The superior rectal artery is the continuation of the inferior mesenteric artery and is the principal supply to the upper rectum. The middle rectal (internal iliac) supplies the middle third; the inferior rectal (internal pudendal) supplies the lower rectum and anal canal."),

(20,
 "The median sacral artery arises from which vessel?",
 ["Right common iliac artery",
  "Posterior aspect of the abdominal aorta just above its bifurcation",
  "Internal iliac artery",
  "Inferior mesenteric artery"],
 "B",
 "The median sacral artery arises from the posterior surface of the abdominal aorta just above its bifurcation at L4. It descends in the midline over the sacrum and coccyx and is at risk during anterior approaches to the lumbar spine."),

(21,
 "Which vessels supply the lumbar vertebral bodies and are at risk during anterior lumbar spine surgery?",
 ["Posterior intercostal arteries",
  "Segmental lumbar arteries from the abdominal aorta",
  "Iliolumbar artery",
  "Lateral sacral artery"],
 "B",
 "Four pairs of lumbar arteries arise from the posterior aspect of the abdominal aorta supplying the lumbar vertebral bodies, spinal cord (via spinal branches), and posterior abdominal wall muscles. They must be carefully ligated during anterior lumbar discectomy or fusion."),

(22,
 "The internal pudendal artery exits the pelvis through which foramen, and then re-enters the perineum through which?",
 ["Exits via greater sciatic foramen; re-enters via lesser sciatic foramen (through the pudendal canal)",
  "Exits and re-enters via greater sciatic foramen",
  "Exits via obturator foramen; re-enters via lesser sciatic foramen",
  "Exits via lesser sciatic foramen only"],
 "A",
 "The internal pudendal artery exits via the greater sciatic foramen (below piriformis), winds around the ischial spine/sacrospinous ligament, and re-enters the perineum via the lesser sciatic foramen, then passes through Alcock's (pudendal) canal."),

(23,
 "The obturator artery most commonly arises from which vessel?",
 ["External iliac artery",
  "Anterior division of internal iliac artery",
  "Femoral artery",
  "Inferior epigastric artery"],
 "B",
 "The obturator artery usually arises from the anterior division of the internal iliac artery. However, in approximately 20-30% of individuals it arises from the inferior epigastric artery (a 'corona mortis') – dangerous during hernia repair if unrecognized and damaged."),

(24,
 "'Corona mortis' refers to an anastomosis between which two vessels, and why is it clinically dangerous?",
 ["Femoral and obturator arteries – risk during femoral hernia repair",
  "Inferior epigastric and obturator arteries/veins – risk during inguinal/pelvic fracture surgery",
  "Internal pudendal and inferior rectal – risk during haemorrhoidectomy",
  "Median sacral and lateral sacral – risk during sacral surgery"],
 "B",
 "Corona mortis ('crown of death') is an anastomosis between the inferior epigastric vessels and obturator vessels along the superior pubic ramus. It is encountered during laparoscopic inguinal hernia repair, pelvic fracture fixation, and retropubic procedures. Unrecognized injury causes severe haemorrhage."),

(25,
 "Batson's vertebral venous plexus is clinically significant because it:",
 ["Drains directly into the portal system",
  "Provides a valveless route for metastatic spread from pelvic/abdominal organs to vertebrae and brain",
  "Is the main venous drainage of the lumbar spinal cord",
  "Communicates only with the azygos system"],
 "B",
 "Batson's plexus is a valveless network surrounding the vertebral column communicating with pelvic, thoracic, and cranial venous systems. Its valveless nature allows retrograde flow, explaining why prostate, breast, and renal carcinomas frequently metastasize to vertebrae and skull without passing through the lungs."),

# ─── SECTION C ───────────────────────────────────────────────────────────────
(26,
 "The superior gluteal artery passes through which space relative to the piriformis muscle?",
 ["Below the piriformis (infrapiriform foramen)",
  "Above the piriformis (suprapiriform foramen)",
  "Through the piriformis muscle",
  "Through the obturator foramen"],
 "B",
 "The superior gluteal artery, vein, and nerve pass through the suprapiriform foramen (greater sciatic foramen above piriformis). The inferior gluteal artery and nerve, and the sciatic nerve, pass through the infrapiriform foramen (below piriformis)."),

(27,
 "A patient receives a misplaced IM injection in the upper medial quadrant of the buttock. Which structure is most at risk?",
 ["Superior gluteal nerve",
  "Sciatic nerve",
  "Inferior gluteal nerve",
  "Pudendal nerve"],
 "B",
 "The sciatic nerve descends through the infrapiriform portion of the greater sciatic foramen and runs in the lower medial quadrant of the gluteal region. Safe IM injection sites are the upper outer quadrant or the ventrogluteal site. Injection in the upper medial quadrant can damage the sciatic nerve, causing foot drop."),

(28,
 "The femoral triangle is bounded by which three structures?",
 ["Inguinal ligament (superior), sartorius (lateral), adductor longus (medial)",
  "Inguinal ligament (superior), sartorius (medial), rectus femoris (lateral)",
  "Poupart's ligament (inferior), iliacus (lateral), pectineus (medial)",
  "Inguinal ligament, iliopsoas, gracilis"],
 "A",
 "The femoral triangle has the inguinal ligament as its superior base, sartorius as its lateral border, and adductor longus as its medial border. Its floor is formed by iliopsoas (laterally) and pectineus (medially). Its roof is the fascia lata with the saphenous opening."),

(29,
 "In the femoral sheath, from lateral to medial, the correct order of contents is:",
 ["Femoral nerve, femoral artery, femoral vein, femoral canal",
  "Femoral artery, femoral vein, femoral canal (femoral nerve is outside the sheath)",
  "Femoral vein, femoral artery, femoral nerve, femoral canal",
  "Femoral canal, femoral vein, femoral artery, femoral nerve"],
 "B",
 "The femoral sheath contains, from lateral to medial: femoral artery, femoral vein, and femoral canal (containing lymphatics and Cloquet's node). The femoral nerve lies lateral to the sheath and is NOT enclosed within it – important in femoral nerve blocks and hernia repairs."),

(30,
 "The profunda femoris (deep femoral) artery arises how far below the inguinal ligament and primarily supplies which compartment?",
 ["1 cm; anterior compartment",
  "3–5 cm; posterior and medial compartments of the thigh",
  "8 cm; lateral compartment",
  "2 cm; adductor compartment only"],
 "B",
 "The profunda femoris arises from the lateral aspect of the femoral artery approximately 3–5 cm below the inguinal ligament. It is the main supply to the posterior and medial thigh compartments via perforating branches, and gives rise to medial and lateral femoral circumflex arteries."),

(31,
 "A 70-year-old man with peripheral vascular disease has superficial femoral artery occlusion in the adductor canal. Which collateral pathway is most important?",
 ["Obturator to medial femoral circumflex anastomosis",
  "Profunda femoris perforating branches to popliteal artery genicular branches",
  "Lateral femoral circumflex to anterior tibial recurrent",
  "Superior gluteal to inferior gluteal anastomosis"],
 "B",
 "When the superficial femoral artery occludes in Hunter's canal, the key collateral is between the perforating branches of profunda femoris and the genicular branches of the popliteal artery (especially the descending genicular artery). This anastomosis around the knee is vital in chronic occlusion."),

(32,
 "From deep to superficial in the popliteal fossa, the correct order of neurovascular structures is:",
 ["Popliteal vein, popliteal artery, tibial nerve",
  "Popliteal artery, popliteal vein, tibial nerve",
  "Tibial nerve, popliteal vein, popliteal artery",
  "Popliteal artery, tibial nerve, popliteal vein"],
 "B",
 "From deep to superficial: popliteal artery (deepest, directly posterior to the knee joint), popliteal vein (intermediate), tibial nerve (most superficial/posterior). Remember 'AVN – deep to superficial' (Artery, Vein, Nerve)."),

(33,
 "The popliteal artery terminates by dividing into anterior and posterior tibial arteries at which level?",
 ["Level of the femoral condyles",
  "Lower border of popliteus muscle",
  "Upper border of popliteus",
  "At the level of the fibular head"],
 "B",
 "The popliteal artery ends at the lower border of popliteus, dividing into the anterior tibial artery (passes through a gap in the upper interosseous membrane to the anterior compartment) and the posterior tibial artery (continues in the deep posterior compartment)."),

(34,
 "The dorsalis pedis artery is the continuation of which vessel, and where is its pulse palpated?",
 ["Posterior tibial artery; behind the medial malleolus",
  "Anterior tibial artery; on the dorsum of the foot between the 1st and 2nd extensor tendons",
  "Peroneal artery; anterior to the lateral malleolus",
  "Lateral plantar artery; over the lateral cuneiform"],
 "B",
 "The dorsalis pedis is the continuation of the anterior tibial artery as it crosses the ankle. Its pulse is palpated on the dorsum of the foot, just lateral to the extensor hallucis longus tendon (between the 1st and 2nd metatarsals). It is assessed during peripheral vascular examination."),

(35,
 "The great saphenous vein drains into the femoral vein at which point?",
 ["At the popliteal fossa",
  "At the saphenofemoral junction, 3–4 cm inferolateral to the pubic tubercle",
  "At the adductor canal",
  "At the inguinal ligament"],
 "B",
 "The great saphenous vein drains into the femoral vein at the saphenofemoral junction, approximately 3–4 cm inferolateral to the pubic tubercle (at the saphenous opening in the fascia lata). This junction is the key target in varicose vein surgery (Trendelenburg operation)."),

(36,
 "A 55-year-old woman has chronic venous ulcers just above the medial malleolus. This is due to incompetent perforating veins connecting which two systems?",
 ["Great saphenous vein to femoral vein",
  "Superficial venous system to deep venous system via medial perforators (Cockett's perforators)",
  "Short saphenous vein to popliteal vein",
  "Deep to superficial via lateral perforators"],
 "B",
 "Venous ulcers in the 'gaiter area' result from incompetent medial perforating veins (Cockett's perforators), causing high-pressure retrograde flow from deep to superficial system. This produces venous hypertension, lipodermatosclerosis, and eventually ulceration."),

(37,
 "The posterior tibial artery pulse is palpated at which site?",
 ["Anterior to the medial malleolus",
  "In the midline posterior to the ankle",
  "Posterior to the medial malleolus, midway between it and the calcaneal tendon",
  "Just below the lateral malleolus"],
 "C",
 "The posterior tibial artery passes posterior to the medial malleolus beneath the flexor retinaculum, midway between the medial malleolus and the heel. It divides into medial and lateral plantar arteries in the sole of the foot."),

(38,
 "The lateral plantar artery anastomoses with the dorsalis pedis artery to form which arch?",
 ["Superficial plantar arch",
  "Deep plantar arch",
  "Plantar digital arch",
  "Dorsal metatarsal arch"],
 "B",
 "The lateral plantar artery curves medially across the foot to anastomose with the deep plantar artery (branch of dorsalis pedis passing between 1st and 2nd metatarsal heads) to form the deep plantar arch – analogous to the deep palmar arch in the hand."),

# ─── SECTION D ───────────────────────────────────────────────────────────────
(39,
 "In fetal circulation, oxygenated blood from the placenta reaches the fetus via which vessel?",
 ["Two umbilical arteries",
  "One umbilical vein",
  "Ductus arteriosus",
  "Ductus venosus"],
 "B",
 "The single umbilical vein carries oxygenated, nutrient-rich blood from the placenta to the fetus. The two umbilical arteries carry deoxygenated blood back to the placenta. This is the only vein in the body that carries oxygenated blood."),

(40,
 "The ductus venosus allows oxygenated blood from the umbilical vein to bypass the liver. Into which vessel does it drain?",
 ["Portal vein",
  "Hepatic vein",
  "Inferior vena cava",
  "Right atrium directly"],
 "C",
 "The ductus venosus connects the left branch of the portal vein to the IVC, allowing approximately 50% of umbilical venous blood to bypass the liver sinusoids and enter the IVC directly, delivering higher oxygen-saturation blood to the right atrium."),

(41,
 "In the fetal heart, the foramen ovale allows blood to flow from:",
 ["Left atrium to right atrium",
  "Right atrium to left atrium",
  "Right ventricle to left ventricle",
  "Left ventricle to right ventricle"],
 "B",
 "Right atrial pressure exceeds left atrial pressure in the fetus (lungs not yet inflating), so blood flows right to left through the foramen ovale, directing better-oxygenated IVC blood to the left side and then to the brain and coronary arteries."),

(42,
 "The ductus arteriosus connects which two vessels in fetal life?",
 ["Pulmonary vein to aorta",
  "Pulmonary trunk to the descending aorta just distal to the left subclavian artery",
  "Superior vena cava to aortic arch",
  "Right ventricle directly to aorta"],
 "B",
 "The ductus arteriosus connects the pulmonary trunk to the descending aorta just distal to the origin of the left subclavian artery. It allows most right ventricular output to bypass the high-resistance fetal pulmonary circulation. It is kept patent by low PO2 and prostaglandin E2."),

(43,
 "What is the approximate oxygen saturation of blood in the umbilical vein/ductus venosus in fetal life?",
 ["20%",
  "40%",
  "80%",
  "98%"],
 "C",
 "Blood in the umbilical vein has a PO2 of approximately 30–35 mmHg with oxygen saturation around 80%. This is the most oxygenated blood in the fetal circulation. After mixing with deoxygenated blood in the IVC, saturation falls to approximately 67%."),

(44,
 "At birth, the foramen ovale closes functionally because:",
 ["The ductus arteriosus constricts",
  "Left atrial pressure rises above right atrial pressure as pulmonary blood flow increases",
  "The umbilical vein is clamped",
  "Systemic vascular resistance falls"],
 "B",
 "With the first breath, pulmonary vascular resistance drops dramatically, increasing pulmonary blood flow and left atrial return. Left atrial pressure now exceeds right atrial pressure, pressing the septum primum flap against septum secundum, functionally closing the foramen ovale."),

(45,
 "What is the fate of the ductus arteriosus after birth?",
 ["Becomes the ligamentum arteriosum",
  "Becomes the ligamentum teres hepatis",
  "Becomes the ligamentum venosum",
  "Becomes the medial umbilical ligament"],
 "A",
 "The ductus arteriosus constricts within hours of birth (rising PO2, falling prostaglandins) and obliterates over several weeks to become the ligamentum arteriosum – a fibrous cord connecting the left pulmonary artery to the aortic arch. This remnant marks the position of the left recurrent laryngeal nerve."),

(46,
 "What is the fate of the umbilical vein after birth?",
 ["Ligamentum arteriosum",
  "Ligamentum venosum",
  "Ligamentum teres hepatis (round ligament of liver) in the free edge of the falciform ligament",
  "Medial umbilical ligament"],
 "C",
 "The umbilical vein obliterates to become the ligamentum teres hepatis (round ligament of the liver), running in the free inferior edge of the falciform ligament from the umbilicus to the porta hepatis. It can be surgically recanalized in portal hypertension."),

(47,
 "The ductus venosus becomes which ligament after birth?",
 ["Ligamentum teres hepatis",
  "Ligamentum venosum",
  "Ligamentum arteriosum",
  "Median umbilical ligament"],
 "B",
 "The ductus venosus obliterates and becomes the ligamentum venosum, a fibrous cord on the posterior surface of the liver in the fissure between the left lobe and the caudate lobe."),

(48,
 "The two umbilical arteries, after birth, become which structures?",
 ["Ligamenta teres hepatis",
  "Medial umbilical ligaments (within the medial umbilical folds of the anterior abdominal wall)",
  "Lateral umbilical folds",
  "Inguinal ligaments"],
 "B",
 "The distal portions of the umbilical arteries obliterate to become the medial umbilical ligaments, visible as ridges (medial umbilical folds) on the deep surface of the anterior abdominal wall. The proximal portions persist as the superior vesical arteries supplying the bladder fundus."),

(49,
 "In which week of embryonic development does the heart begin to beat?",
 ["Week 2",
  "Week 4",
  "Week 6",
  "Week 8"],
 "B",
 "The heart begins to beat around day 22–23 (early Week 4), making it the first organ to function. The primitive heart tube starts contracting before it has completed looping and septation."),

(50,
 "The primitive heart tube undergoes rightward (dextral) looping at approximately which developmental stage?",
 ["Carnegie Stage 10 – approximately day 22–23",
  "Carnegie Stage 13 – approximately day 28–30",
  "Carnegie Stage 8 – approximately day 17–19",
  "Carnegie Stage 15 – approximately day 33–36"],
 "A",
 "Cardiac looping (D-looping) begins at approximately day 22–23 (Carnegie Stage 10). This brings the future right ventricle to the right and the left ventricle to the left. Abnormal leftward looping (L-looping) leads to situs inversus or levocardia."),

(51,
 "The interventricular septum consists of two components. What closes the interventricular foramen?",
 ["Muscular part (from floor of primitive ventricle) and membranous part (from endocardial cushions and conotruncal ridges)",
  "Muscular part only, closed by endocardial cushions",
  "Membranous part only, from endocardial cushions",
  "Conotruncal ridges entirely"],
 "A",
 "The muscular part grows upward from the ventricular floor. The membranous part, which closes the interventricular foramen superiorly, is derived from endocardial cushion tissue and the right and left conotruncal ridges. Failure of membranous closure produces the most common type of VSD."),

(52,
 "The truncus arteriosus and bulbus cordis are divided by which structure into the aorta and pulmonary trunk?",
 ["Endocardial cushions",
  "Septum primum",
  "Aorticopulmonary septum (formed by spiraling conotruncal ridges)",
  "Septum secundum"],
 "C",
 "The aorticopulmonary (conotruncal) septum forms by fusion of spiraling right and left conotruncal ridges. This spiral creates the twisting relationship between the aorta and pulmonary trunk. Abnormal development produces transposition of the great arteries, truncus arteriosus persistens, and tetralogy of Fallot."),

(53,
 "Which of the following correctly describes interatrial septum formation?",
 ["Septum primum grows downward; ostium primum then ostium secundum form; septum secundum grows as a thick crescent leaving the foramen ovale",
  "Septum secundum grows first, then septum primum",
  "Both septa grow from endocardial cushions simultaneously",
  "The septum is entirely derived from neural crest cells"],
 "A",
 "Septum primum grows down toward the endocardial cushions, leaving the ostium primum. Before it closes, apoptosis creates the ostium secundum above. Septum secundum then grows as a thick muscular crescent to the right, leaving the foramen ovale, which the thin septum primum covers as a flap valve."),

(54,
 "Which fetal vascular structure becomes the fossa ovalis in the adult heart?",
 ["Septum secundum",
  "Septum primum (the flap portion that covered the foramen ovale)",
  "The entire foramen ovale",
  "The muscular interventricular septum"],
 "B",
 "The fossa ovalis (thin central depression in the adult interatrial septum) represents the remnant of septum primum. The annulus ovalis (raised rim around the fossa) represents the lower free edge of septum secundum. A patent foramen ovale occurs when septum primum fails to fuse with septum secundum."),

(55,
 "The arch of the aorta develops from which pharyngeal arch artery?",
 ["1st pharyngeal arch artery",
  "3rd pharyngeal arch artery",
  "4th pharyngeal arch artery (left side)",
  "6th pharyngeal arch artery"],
 "C",
 "The left 4th pharyngeal arch artery persists as the arch of the aorta. The right 4th arch forms the right subclavian artery (proximal segment). The 3rd arches become the common carotid arteries and proximal internal carotids. The 6th arches form the pulmonary arteries and (left side) the ductus arteriosus."),

# ─── SECTION E ───────────────────────────────────────────────────────────────
(56,
 "What is the PRIMARY (initiating) embryological defect in Tetralogy of Fallot?",
 ["Pulmonary stenosis",
  "Ventricular septal defect",
  "Anterosuperior displacement of the infundibular (conoventricular) septum",
  "Right ventricular hypertrophy"],
 "C",
 "All four defects of Tetralogy of Fallot (VSD, pulmonary stenosis, overriding aorta, RV hypertrophy) result from a single primary defect: anterior and superior displacement of the infundibular septum. Right ventricular hypertrophy is a secondary consequence of pressure overload."),

(57,
 "A newborn presents with cyanosis, a harsh ejection systolic murmur, and a boot-shaped heart with decreased pulmonary vascular markings on CXR. What is the diagnosis?",
 ["Transposition of the great arteries",
  "Tetralogy of Fallot",
  "Tricuspid atresia",
  "Total anomalous pulmonary venous return"],
 "B",
 "The boot-shaped heart (coeur en sabot – RV hypertrophy lifting apex, concave pulmonary bay) and decreased pulmonary markings are classic features of Tetralogy of Fallot. Cyanotic 'tet spells' worsen with crying as infundibular spasm increases right-to-left shunting."),

(58,
 "Transposition of the great arteries (D-TGA) results from failure of the aorticopulmonary septum to:",
 ["Form at all",
  "Spiral (rotate) during partitioning of the truncus arteriosus",
  "Fuse with the endocardial cushions",
  "Develop the conotruncal ridges"],
 "B",
 "In D-TGA, the aorticopulmonary septum forms but fails to spiral, resulting in a straight septum. This places the aorta anterior and to the right (from the RV) and the pulmonary trunk posterior (from the LV), creating parallel rather than crossed circulations – incompatible with life without a mixing lesion."),

(59,
 "A 3-day-old neonate presents with severe cyanosis unresponsive to oxygen. Echo shows the aorta arising from the right ventricle and pulmonary trunk from the left ventricle. What is the immediate management?",
 ["Surgical arterial switch only",
  "Balloon atrial septostomy (Rashkind procedure) only",
  "Prostaglandin E1 infusion only",
  "Both balloon atrial septostomy AND prostaglandin E1 infusion"],
 "D",
 "Both interventions are used in D-TGA. Prostaglandin E1 maintains ductal patency to allow mixing; balloon atrial septostomy (Rashkind procedure) enlarges the foramen ovale to create an atrial-level shunt. Together they stabilize the infant until definitive arterial switch operation (Jatene procedure)."),

(60,
 "Patent ductus arteriosus (PDA) is most common in which group and what murmur does it produce?",
 ["Term infants; pan-systolic murmur",
  "Premature infants; continuous 'machinery' murmur in the left infraclavicular region",
  "Post-term infants; early diastolic murmur",
  "Term infants with Down syndrome; mid-diastolic murmur"],
 "B",
 "PDA is common in premature infants (elevated prostaglandin levels). It produces a continuous 'machinery' or 'train in tunnel' murmur loudest in the left infraclavicular region, because blood flows from the high-pressure aorta to the lower-pressure pulmonary artery in both systole and diastole."),

(61,
 "Coarctation of the aorta most commonly occurs at which site?",
 ["Ascending aorta, just above the aortic valve",
  "At the isthmus of the aorta, distal to the left subclavian artery at the level of the ligamentum arteriosum",
  "At the level of the diaphragm (abdominal aorta)",
  "Just proximal to the left subclavian artery"],
 "B",
 "Coarctation most commonly occurs at the aortic isthmus, just distal to the origin of the left subclavian artery at the level of the ligamentum arteriosum (juxtaductal type). Clinically: hypertension in upper limbs, diminished/delayed femoral pulses, and rib notching on CXR from enlarged intercostal collaterals."),

(62,
 "A 20-year-old has hypertension in both arms and weak femoral pulses. CXR shows posterior rib notching (3rd–8th ribs). What is the embryological basis?",
 ["Abnormal looping of the heart tube",
  "Excessive narrowing at the aortic isthmus, related to abnormal remodeling of the 4th aortic arch/ductal tissue",
  "Failure of the truncus arteriosus to divide",
  "Absence of the 3rd pharyngeal arch artery"],
 "B",
 "Coarctation results from abnormal extension of ductal smooth muscle tissue into the adjacent aortic wall ('ductal sling' theory) combined with hemodynamic factors. Rib notching is caused by enlarged posterior intercostal arteries serving as collateral channels bypassing the coarctation."),

(63,
 "In an atrial septal defect of the ostium secundum type, the defect is located where?",
 ["In the lower part of the interatrial septum near the AV valves",
  "In the central region of the interatrial septum (fossa ovalis region) due to excessive resorption of septum primum or inadequate growth of septum secundum",
  "In the upper part of the interatrial septum near the SVC",
  "In the ventricular septum"],
 "B",
 "Ostium secundum ASD (~70% of ASDs) occurs due to excessive apoptotic resorption of septum primum or inadequate growth of septum secundum. Ostium primum ASD (endocardial cushion defect) occurs low in the septum near the AV valves and is associated with Down syndrome."),

(64,
 "An anomalous right subclavian artery (arteria lusoria) has a retroesophageal course. What is the embryological basis?",
 ["Persistence of the right 4th arch artery",
  "Abnormal regression of the right 4th arch artery with persistence of the right dorsal aorta distal to the 7th intersegmental artery",
  "Failure of the right 3rd arch to develop",
  "Persistence of the right 6th arch artery"],
 "B",
 "In arteria lusoria, the right 4th arch and the right dorsal aorta between the 4th and 7th intersegmental arteries regress, so the right subclavian arises from the descending aorta and passes behind the esophagus to reach the right arm, causing dysphagia lusoria."),

(65,
 "The paired dorsal aortae fuse to form the descending aorta at which embryological period?",
 ["Week 2, between T4 and L4 vertebral levels",
  "Week 4, between the 4th thoracic and 4th lumbar vertebral levels",
  "Week 6, only below the diaphragm",
  "Week 8, throughout the thorax"],
 "B",
 "During Week 4, the two dorsal aortae fuse in the midline between T4 and L4 levels to form the single descending aorta. The cranial portions remain paired (contributing to the carotid system) and the caudal portions fuse (contributing to the common iliac arteries)."),

(66,
 "The superior vena cava (SVC) develops from which embryological veins?",
 ["Right vitelline vein and right umbilical vein",
  "Right common cardinal vein and right anterior cardinal vein",
  "Left anterior cardinal vein",
  "Right and left posterior cardinal veins"],
 "B",
 "The SVC forms from the right common cardinal vein (right duct of Cuvier) and the right anterior cardinal vein. The left common cardinal vein normally regresses to become the oblique vein of the left atrium (vein of Marshall) and the coronary sinus."),

(67,
 "A persistent left superior vena cava (PLSVC) draining into the coronary sinus is found incidentally on echo. What is the embryological basis?",
 ["Failure of the right common cardinal vein to develop",
  "Failure of regression of the left common cardinal vein",
  "Abnormal development of the left subclavian vein",
  "Persistence of the left vitelline vein"],
 "B",
 "PLSVC results from failure of the left common cardinal vein (left duct of Cuvier) to regress. Present in ~0.3–0.5% of the general population. It is important to identify before cardiac catheterization, pacemaker implantation, or left internal jugular cannulation."),

(68,
 "Which congenital heart defect is most commonly associated with Down syndrome (Trisomy 21)?",
 ["Tetralogy of Fallot",
  "Atrioventricular septal defect (AVSD / endocardial cushion defect)",
  "Transposition of the great arteries",
  "Coarctation of the aorta"],
 "B",
 "Atrioventricular septal defect (AV canal defect) is the most common cardiac defect in Down syndrome, occurring in approximately 40% of those with congenital heart disease. It results from failure of the endocardial cushions to fuse properly."),

# ─── SECTION F ───────────────────────────────────────────────────────────────
(69,
 "The largest paranasal sinus drains into the middle meatus of the nasal cavity. Which sinus is this?",
 ["Frontal sinus",
  "Sphenoid sinus",
  "Maxillary sinus (antrum of Highmore)",
  "Ethmoidal sinuses"],
 "C",
 "The maxillary sinus is the largest paranasal sinus. It drains via the maxillary ostium (hiatus semilunaris) into the middle meatus. Its drainage is poor because the ostium is high on the medial wall near the roof, making it prone to chronic sinusitis and dependent fluid retention."),

(70,
 "A patient presents with cheek pain, nasal discharge, and toothache in the upper molars following an URTI. Which sinus is most likely infected?",
 ["Frontal sinus",
  "Ethmoidal sinus",
  "Maxillary sinus",
  "Sphenoidal sinus"],
 "C",
 "Maxillary sinusitis presents with cheek pain/tenderness, nasal congestion, and toothache in the upper molar/premolar teeth (roots may project into the floor of the maxillary sinus). The maxillary sinus is the most commonly infected paranasal sinus."),

(71,
 "The sphenoid sinus is related superiorly to which important structure, making sphenoidal sinusitis potentially dangerous?",
 ["Middle cranial fossa and pituitary gland (sella turcica)",
  "Anterior cranial fossa and olfactory bulbs",
  "Posterior cranial fossa and basilar artery",
  "Internal carotid artery only"],
 "A",
 "The sphenoid sinus lies immediately below the sella turcica and is closely related to the pituitary gland, optic chiasm, cavernous sinus, and internal carotid artery. Sphenoidal sinusitis can cause cavernous sinus thrombosis or pituitary abscess. The transsphenoidal approach to the pituitary passes through this sinus."),

(72,
 "Which paranasal sinuses are present at birth?",
 ["All four pairs are present at birth",
  "Only the maxillary and ethmoid sinuses are present at birth (rudimentary)",
  "Only the frontal sinuses",
  "Only the sphenoidal sinus"],
 "B",
 "Only the maxillary and ethmoid sinuses are present (rudimentary) at birth. Frontal sinuses begin developing around age 2 years (radiologically visible by age 6–7). Sphenoidal sinuses begin pneumatizing around age 3. All sinuses reach adult size after puberty."),

(73,
 "The inferior meatus of the nasal cavity, beneath the inferior concha, receives the opening of which structure?",
 ["Maxillary sinus",
  "Frontal sinus via the infundibulum",
  "Nasolacrimal duct",
  "Sphenoethmoidal recess"],
 "C",
 "The nasolacrimal duct opens into the inferior meatus beneath the inferior concha. This explains why crying causes a runny nose – tears drain through the nasolacrimal duct into the nasal cavity. Neonatal congenital nasolacrimal duct obstruction causes persistent medial canthal discharge."),

(74,
 "The ostiomeatal complex (OMC) is the common drainage pathway for which sinuses?",
 ["Sphenoidal and posterior ethmoidal sinuses",
  "Frontal, anterior ethmoidal, and maxillary sinuses (draining into the middle meatus)",
  "All paranasal sinuses",
  "Only the maxillary sinus"],
 "B",
 "The ostiomeatal complex in the middle meatus includes the maxillary sinus ostium, infundibulum, hiatus semilunaris, anterior ethmoidal cells, and frontal recess. Obstruction here leads to chronic rhinosinusitis of all three anterior sinuses. Functional endoscopic sinus surgery (FESS) targets this region."),

(75,
 "Kiesselbach's area (Little's area) – the most common site for epistaxis – receives blood from which arteries?",
 ["Only the posterior ethmoidal artery",
  "Anterior ethmoidal, posterior ethmoidal, sphenopalatine, greater palatine, and superior labial arteries (branches of both internal and external carotid systems)",
  "Only the sphenopalatine artery",
  "Internal carotid artery branches only"],
 "B",
 "Kiesselbach's plexus on the anteroinferior nasal septum receives blood from both internal carotid (anterior/posterior ethmoidal arteries) and external carotid (sphenopalatine, greater palatine, superior labial) systems. Most nosebleeds (90%) originate here."),

(76,
 "The olfactory nerve (CN I) passes through which structure to reach the olfactory bulb?",
 ["Cribriform plate of the ethmoid bone",
  "Crista galli of the ethmoid",
  "Lamina papyracea",
  "Foramen cecum"],
 "A",
 "The olfactory nerve filaments (~20 on each side) pass through the numerous foramina of the cribriform plate of the ethmoid bone to synapse in the olfactory bulb. Fractures of the anterior cranial fossa/cribriform plate can tear these filaments (anosmia) and create a CSF rhinorrhoea pathway."),

# ─── SECTION G ───────────────────────────────────────────────────────────────
(77,
 "The recurrent laryngeal nerve loops around which structure on the RIGHT side and which on the LEFT?",
 ["Right: loops around the right subclavian artery; Left: loops around the arch of the aorta (ligamentum arteriosum)",
  "Right: loops around the aorta; Left: loops around the subclavian artery",
  "Both sides loop around the common carotid artery",
  "Right: loops around the brachiocephalic artery; Left: loops around the pulmonary trunk"],
 "A",
 "On the right, the RLN loops around the right subclavian artery (remnant of right 4th arch/dorsal aorta); on the left, it loops around the arch of the aorta at the ligamentum arteriosum (remnant of left 6th arch). The left RLN has a longer intrathoracic course making it more susceptible to mediastinal pathology."),

(78,
 "A patient develops hoarseness after thyroid surgery with the left vocal fold fixed in the paramedian position. Which nerve was injured and what muscles does it supply?",
 ["External branch of superior laryngeal nerve; cricothyroid",
  "Recurrent laryngeal nerve; all intrinsic laryngeal muscles EXCEPT cricothyroid",
  "Glossopharyngeal nerve; stylopharyngeus",
  "Superior laryngeal nerve internal branch; all intrinsic laryngeal muscles"],
 "B",
 "The recurrent laryngeal nerve supplies all intrinsic laryngeal muscles except cricothyroid (supplied by the external branch of the superior laryngeal nerve). RLN injury causes ipsilateral vocal fold paralysis. Bilateral RLN injury causes stridor and respiratory distress."),

(79,
 "The external branch of the superior laryngeal nerve (EBSLN) is at risk during which step of thyroidectomy, and its injury produces which voice change?",
 ["Ligation of the inferior thyroid artery – hoarseness",
  "Ligation of the superior thyroid artery close to the upper pole – loss of high-pitched phonation and vocal fatigue",
  "Dissection of the middle thyroid vein – complete voice loss",
  "Retraction of the trachea – loss of cough reflex"],
 "B",
 "The EBSLN (supplying cricothyroid – the pitch-modulator of the vocal fold) runs close to the superior thyroid artery. Injury produces a subtle change: loss of high-pitched phonation, easy vocal fatigue, and inability to sing high notes ('Amelita Galli-Curci' injury)."),

(80,
 "A left-sided lung carcinoma causes hoarseness. Why is the left RLN more vulnerable to mediastinal tumors?",
 ["It runs through the neck only",
  "It has a longer intrathoracic course, looping around the aortic arch in close proximity to mediastinal lymph nodes and the left hilum",
  "It runs with the right vagus",
  "It crosses the trachea in the mediastinum"],
 "B",
 "The left RLN loops around the arch of the aorta (ligamentum arteriosum), then ascends in the tracheoesophageal groove. Its long mediastinal course means it is closely related to the left hilar lymph nodes and aorto-pulmonary window – commonly involved by left lung carcinoma, lymphoma, and aortic aneurysms."),

(81,
 "Which deep cervical lymph node is called the 'sentinel node' for many head and neck cancers?",
 ["Submental nodes",
  "Jugulodigastric node (at the junction of the posterior belly of digastric and internal jugular vein)",
  "Submandibular nodes",
  "Occipital nodes"],
 "B",
 "The jugulodigastric (tonsillar) node lies at the angle of the jaw where the posterior belly of digastric crosses the internal jugular vein. It is the first node to enlarge in tonsillar infections and oropharyngeal/tongue-base carcinoma."),

(82,
 "The thoracic duct (left lymphatic duct) empties into which venous junction?",
 ["Right subclavian–right internal jugular (right venous angle)",
  "Left subclavian–left internal jugular junction (left jugulosubclavian junction)",
  "Superior vena cava directly",
  "Left brachiocephalic vein"],
 "B",
 "The thoracic duct empties into the venous system at the left jugulosubclavian junction (angle between the left internal jugular and left subclavian veins). The right lymphatic duct drains into the right venous angle. Thoracic duct injury (e.g., during left neck dissection) causes chylothorax or chylous fistula."),

(83,
 "Tracheoesophageal fistula (TEF) most commonly occurs in which anatomical configuration?",
 ["Isolated esophageal atresia without fistula (Type A)",
  "Esophageal atresia with a distal TEF (Type C) – upper esophagus ends in a blind pouch, lower esophagus communicates with trachea",
  "H-type fistula without esophageal atresia (Type E)",
  "Esophageal atresia with proximal TEF only (Type B)"],
 "B",
 "Type C TEF (Gross/Vogt classification) is the most common type (~85–87%). The upper esophageal segment ends as a blind pouch (excessive salivation, unable to swallow) while the lower segment connects to the trachea (air in stomach on CXR, aspiration pneumonia)."),

(84,
 "A neonate presents with excessive drooling, choking with first feed, and respiratory distress. CXR shows a coiled NG tube in the chest and air in the stomach. What is the diagnosis and embryological basis?",
 ["Congenital diaphragmatic hernia – failure of pleuroperitoneal canal closure",
  "Esophageal atresia with distal TEF (Type C) – failure of the tracheoesophageal septum to completely separate the foregut",
  "Congenital lobar emphysema – deficient bronchial cartilage",
  "Choanal atresia – failure of bucconasal membrane to rupture"],
 "B",
 "The coiled NG tube indicates esophageal atresia (cannot advance past the blind pouch); air in the stomach confirms a distal fistula. Embryologically, the tracheoesophageal septum fails to completely divide the foregut, leaving a persistent connection between the airway and esophagus."),

(85,
 "The VACTERL association includes which combination of anomalies?",
 ["Vertebral, Anal, Cardiac, Tracheo-Esophageal, Renal/Radial, Limb defects",
  "Ventricular defect, Aortic stenosis, Cleft palate, Tracheal agenesis, Ear defects, Radial aplasia, Lip defects",
  "Vertebral fractures, Atrial defects, Coarctation, Tracheomalacia, Esophageal varices, Renal agenesis, Limb girdle weakness",
  "Visceral situs inversus, Atrial defect, Cor triatriatum, TEF, Ear anomaly, Renal ectopia, Leg length discrepancy"],
 "A",
 "VACTERL: Vertebral anomalies, Anal atresia, Cardiac defects (most commonly VSD), Tracheo-Esophageal fistula/atresia, Renal anomalies and Radial defects, Limb defects (especially radial ray). When TEF is diagnosed, all these associated anomalies must be actively screened for."),

(86,
 "The larynx develops from which pharyngeal arches?",
 ["1st and 2nd pharyngeal arches only",
  "4th and 6th pharyngeal arch cartilages; the epiglottis from the hypobranchial eminence (3rd/4th arches)",
  "3rd pharyngeal arch only",
  "2nd and 3rd pharyngeal arches"],
 "B",
 "The thyroid cartilage derives from the 4th pharyngeal arch; the arytenoid, cricoid, and corniculate cartilages from the 6th arch. The epiglottis develops from the hypobranchial eminence (3rd and 4th arch mesoderm). Intrinsic laryngeal muscles (except cricothyroid) are innervated by the RLN (CN X, 6th arch)."),

(87,
 "Submental lymph nodes drain which areas and empty into which deeper nodes?",
 ["Tip of tongue, lower lip central portion, chin, floor of mouth – drain to submandibular then to jugulodigastric nodes",
  "Posterior scalp, occipital region – drain directly to deep cervical nodes",
  "Pinna and parotid – drain to pre-auricular nodes then to deep cervical",
  "Lateral tongue – drain directly to jugulodigastric nodes"],
 "A",
 "Submental nodes (between the anterior bellies of digastric and hyoid bone) drain the tip of tongue, incisor teeth/gums, central lower lip, chin, and floor of mouth. They drain sequentially to submandibular nodes then to the superior deep cervical (jugulodigastric) chain."),

(88,
 "The Virchow node (signal node) is a palpable left supraclavicular lymph node. It signifies which malignancy and why?",
 ["Lung cancer – the left lung lymphatics drain here",
  "Intra-abdominal/pelvic malignancy – the thoracic duct drains abdominal lymph into the left venous angle, and retrograde spread reaches the left supraclavicular node",
  "Head and neck cancer – directly via cervical lymphatic chain",
  "Breast cancer – axillary lymphatics drain here directly"],
 "B",
 "Virchow's (Troisier's) node classically signals gastrointestinal (especially gastric), pancreatic, or pelvic malignancy. The thoracic duct collects abdominal lymph and terminates at the left venous angle; overflow/retrograde spread reaches the left supraclavicular nodes. A palpable Virchow node demands urgent upper GI investigation."),

# ─── SECTION H ───────────────────────────────────────────────────────────────
(89,
 "The right main bronchus is more prone to foreign body aspiration than the left. What is the anatomical reason?",
 ["Right bronchus is wider and more horizontal",
  "Right main bronchus is wider, shorter, and more vertical (less angled from the trachea) than the left",
  "Right bronchus is narrower",
  "Right bronchus has a sharper angle"],
 "B",
 "The right main bronchus is wider, shorter (~2.5 cm), and more vertical (~25° from vertical) than the left (~45°). This makes it the preferential site for aspirated foreign bodies, which fall by gravity and follow the more vertical airway."),

(90,
 "The carina is located at the level of T4 (sternal angle). What is its clinical significance?",
 ["It marks the upper limit of the pericardium",
  "It is the most sensitive area triggering the cough reflex during bronchoscopy; widening/splaying on imaging suggests subcarinal lymphadenopathy",
  "It is the site where the thoracic duct crosses the midline",
  "It is the attachment point of the root of the lung"],
 "B",
 "The carina is extremely sensitive to touch, making it the most cough-provoking site during bronchoscopy. Widening or splaying of the carina (carinal angle normally <70°) suggests subcarinal lymph node enlargement from lung cancer, lymphoma, or sarcoidosis."),

(91,
 "Which lobe of the right lung is considered the anatomical equivalent of the lingula of the left lung?",
 ["Right lower lobe",
  "Right middle lobe",
  "Right upper lobe",
  "There is no equivalent"],
 "B",
 "The lingula (part of the upper lobe of the left lung) is considered the anatomical equivalent of the right middle lobe. Both represent the anteromedial basal segment and are characteristically affected by similar disease processes (middle lobe syndrome vs. lingular consolidation)."),

(92,
 "The visceral pleura is insensitive to pain because:",
 ["It is supplied by intercostal vessels; highly sensitive",
  "It is supplied by bronchial/pulmonary vessels and has only autonomic (visceral) innervation",
  "It is supplied by phrenic arteries; sensitive to pain",
  "It is supplied by internal thoracic artery; moderately sensitive"],
 "B",
 "The visceral pleura has only autonomic innervation and is insensitive to pain. The parietal pleura is supplied by intercostal and phrenic arteries and has somatic innervation (intercostal nerves and phrenic nerve), making it highly sensitive to pain – the origin of pleuritic chest pain."),

(93,
 "A pleural effusion accumulates preferentially in which recess?",
 ["Costomediastinal recess",
  "Costodiaphragmatic recess (costophrenic angle)",
  "Vertebromediastinal recess",
  "Pulmonary ligament"],
 "B",
 "The costodiaphragmatic recess is the lowest part of the pleural cavity. Fluid accumulates here by gravity. It extends to approximately the 8th rib in the midclavicular line, 10th rib in the midaxillary line, and 12th rib posteriorly – the safe zone for thoracocentesis."),

(94,
 "During thoracocentesis, why is the needle inserted at the UPPER border of a rib?",
 ["To avoid the intercostal lymphatics",
  "The intercostal neurovascular bundle (vein, artery, nerve) runs in the costal groove on the lower border of each rib",
  "To avoid the periosteum",
  "To avoid the pleural reflection"],
 "B",
 "The intercostal neurovascular bundle runs in the costal groove on the inferior surface of each rib in the order VAN (Vein, Artery, Nerve) from superior to inferior. Inserting a needle just above the upper border of the rib below avoids damage to these structures."),

(95,
 "A pneumothorax on the left side causes tracheal deviation to the right. Which type of pneumothorax does this indicate and what is the urgent management?",
 ["Simple pneumothorax; observation",
  "Tension pneumothorax; immediate needle decompression (2nd ICS, MCL) then chest tube",
  "Spontaneous pneumothorax; aspiration",
  "Traumatic haemopneumothorax; thoracotomy"],
 "B",
 "Tracheal deviation away from the affected side indicates tension pneumothorax – a life-threatening emergency. Air builds under pressure, collapsing the lung, shifting the mediastinum, kinking the IVC, and compressing the contralateral lung. Immediate needle decompression (2nd ICS, MCL) is the first step, followed by chest tube insertion."),

(96,
 "The respiratory diverticulum (lung bud) develops as a ventral outgrowth from the foregut at approximately which week of development?",
 ["Week 2",
  "Late Week 4 (approximately day 24–26)",
  "Week 8",
  "Week 10"],
 "B",
 "The respiratory diverticulum develops as a ventral outgrowth of the foregut endoderm at the end of Week 4 (approximately day 26–28). It initially communicates with the future esophagus and is separated from it by the tracheoesophageal folds/septum. Incomplete separation results in TEF."),

(97,
 "Surfactant production by type II pneumocytes begins in which stage of lung maturation and at approximately what gestational age?",
 ["Pseudoglandular stage (weeks 5–17)",
  "Canalicular stage (weeks 16–25) – surfactant begins at around 24 weeks",
  "Saccular stage (weeks 26–32)",
  "Alveolar stage (32 weeks–8 years postnatal)"],
 "B",
 "The four stages are: pseudoglandular (5–17 wks), canalicular (16–25 wks), saccular (26–32 wks), alveolar (32 wks–8 years). Surfactant production by type II pneumocytes begins during the canalicular stage at approximately 24 weeks gestation. Premature birth before 26–28 weeks risks respiratory distress syndrome (RDS) due to surfactant deficiency."),

(98,
 "Antenatal corticosteroids (betamethasone) are given to mothers at risk of preterm delivery to:",
 ["Stimulate type I pneumocyte differentiation",
  "Accelerate fetal type II pneumocyte maturation and surfactant protein synthesis",
  "Increase maternal oxygen delivery to the fetus",
  "Close the ductus arteriosus prematurely"],
 "B",
 "Antenatal corticosteroids cross the placenta and accelerate fetal lung maturation by inducing type II pneumocyte differentiation and surfactant protein (SP-A, SP-B, SP-C, SP-D) synthesis. Given at 24–34 weeks gestation, they reduce the incidence and severity of RDS by approximately 50%."),

(99,
 "Congenital diaphragmatic hernia (CDH) most commonly occurs on which side and through which developmental defect?",
 ["Right side; through the foramen of Morgagni (retrosternal hernia)",
  "Left side; through the foramen of Bochdalek (posterolateral defect) due to failure of the pleuroperitoneal membrane to close",
  "Left side; through the esophageal hiatus",
  "Right side; through the right pleuroperitoneal canal failure"],
 "B",
 "CDH occurs predominantly on the left side (~80–85%) through the foramen of Bochdalek (posterolateral defect) due to failure of the left pleuroperitoneal membrane to fuse during weeks 6–7. Abdominal viscera herniate into the thorax, compressing the developing lung and causing pulmonary hypoplasia – the main determinant of prognosis."),

(100,
 "A premature neonate at 28 weeks develops progressive respiratory distress within hours of birth. CXR shows bilateral ground-glass opacification with air bronchograms. Blood gas shows hypoxia and hypercapnia. What is the diagnosis and underlying mechanism?",
 ["Congenital pneumonia – bacterial infection",
  "Transient tachypnea of the newborn – retained lung fluid",
  "Respiratory distress syndrome (hyaline membrane disease) – surfactant deficiency leading to alveolar collapse and hyaline membrane formation",
  "Congenital lobar emphysema – overdistension of a lobe"],
 "C",
 "RDS (hyaline membrane disease) classically presents in premature infants within hours of birth. Surfactant deficiency causes high alveolar surface tension, progressive atelectasis on expiration, and V/Q mismatch. Protein-rich fluid leaks into alveolar spaces forming eosinophilic hyaline membranes. Management: exogenous surfactant instillation, CPAP/ventilation, and supportive care."),
]

# ── section metadata ──────────────────────────────────────────────────────────
SECTIONS = [
    ("A", "Vessels of Axilla, Arm, Forearm & Hand | Venous Drainage & Lymphatics of Upper Limb", "1–15"),
    ("B", "Vessels of Pelvis & Back",                                                             "16–25"),
    ("C", "Vasculature of Gluteal Region, Thigh, Leg & Foot",                                    "26–38"),
    ("D", "Development of Cardiovascular System – Fetal & Neonatal Circulation | Fetal Vascular Structures | Heart & Great Vessels", "39–55"),
    ("E", "Developmental Anomalies of Heart & Great Vessels | Fetal Arteries & Veins",            "56–68"),
    ("F", "Respiratory System – Nasal Cavities & Paranasal Sinuses",                             "69–76"),
    ("G", "Larynx, Trachea | Lymphatics of Head & Neck | Recurrent Laryngeal Nerve | TEF",       "77–88"),
    ("H", "Pleurae, Lungs & Tracheobronchial Tree | Development of Respiratory System",           "89–100"),
]

# ── page callbacks ────────────────────────────────────────────────────────────

def on_first_page(canvas, doc):
    canvas.saveState()
    W, H = A4
    # full-width dark-blue header band
    canvas.setFillColor(DARK_BLUE)
    canvas.rect(0, H-130, W, 130, fill=1, stroke=0)

    # title
    canvas.setFont("Helvetica-Bold", 21)
    canvas.setFillColor(WHITE)
    canvas.drawCentredString(W/2, H-48, "MBBS FINAL EXAMINATION PREPARATION")

    canvas.setFont("Helvetica-Bold", 14)
    canvas.drawCentredString(W/2, H-72, "100 Multiple Choice Questions")

    canvas.setFont("Helvetica", 11)
    canvas.setFillColor(LIGHT_BLUE)
    canvas.drawCentredString(W/2, H-92,
        "Reference: Moore's Clinically Oriented Anatomy, 7th Edition")
    canvas.drawCentredString(W/2, H-110,
        "Topics: Upper Limb Vasculature | Pelvic & Back Vessels | Lower Limb Vasculature | "
        "Cardiovascular Development | Respiratory System")

    _footer(canvas, doc)
    canvas.restoreState()


def on_later_pages(canvas, doc):
    canvas.saveState()
    W, H = A4
    # slim header bar
    canvas.setFillColor(DARK_BLUE)
    canvas.rect(0, H-28, W, 28, fill=1, stroke=0)
    canvas.setFont("Helvetica-Bold", 9)
    canvas.setFillColor(WHITE)
    canvas.drawString(2*cm, H-18, "MBBS Final – Moore's COA 100 MCQs")
    canvas.drawRightString(W-2*cm, H-18, "Moore's Clinically Oriented Anatomy, 7th Ed.")
    _footer(canvas, doc)
    canvas.restoreState()


def _footer(canvas, doc):
    W, _ = A4
    canvas.setFont("Helvetica", 8)
    canvas.setFillColor(colors.HexColor("#666666"))
    canvas.drawCentredString(W/2, 1.0*cm, f"Page {doc.page}")
    canvas.setFillColor(GREY_LINE)
    canvas.line(2*cm, 1.4*cm, W-2*cm, 1.4*cm)


# ── build PDF ──────────────────────────────────────────────────────────────────

def build():
    doc = SimpleDocTemplate(
        OUTPUT,
        pagesize=A4,
        leftMargin=2*cm, rightMargin=2*cm,
        topMargin=3.8*cm, bottomMargin=2.2*cm,
        title="MBBS Final – 100 MCQs (Moore's COA)",
        author="Orris Medical AI",
        subject="Moore's Clinically Oriented Anatomy 7th Edition"
    )

    story = []

    # spacing below header on page 1
    story.append(Spacer(1, 0.5*cm))

    # instructions box
    instr = (
        "<b>INSTRUCTIONS:</b>  Each question has ONE best answer. "
        "Read all options before selecting. Clinical stems represent real patient scenarios – "
        "apply anatomical knowledge to clinical reasoning. "
        "Answers with explanations are provided immediately after each question for self-assessment."
    )
    instr_tbl = Table([[Paragraph(instr, ParagraphStyle(
        "Instr", parent=styles["Normal"], fontSize=9,
        fontName="Helvetica", leading=13, textColor=DARK_BLUE
    ))]], colWidths=[17*cm])
    instr_tbl.setStyle(TableStyle([
        ("BACKGROUND",    (0,0), (-1,-1), LIGHT_BLUE),
        ("LINEALL",       (0,0), (-1,-1), 0.5, MID_BLUE),
        ("TOPPADDING",    (0,0), (-1,-1), 8),
        ("BOTTOMPADDING", (0,0), (-1,-1), 8),
        ("LEFTPADDING",   (0,0), (-1,-1), 10),
        ("RIGHTPADDING",  (0,0), (-1,-1), 10),
    ]))
    story.append(instr_tbl)
    story.append(Spacer(1, 0.4*cm))

    # section boundary lookup
    sec_start = {
        "A": 1, "B": 16, "C": 26, "D": 39,
        "E": 56, "F": 69, "G": 77, "H": 89
    }
    sec_iter = iter(SECTIONS)
    current_sec = next(sec_iter)
    next_sec_start = 16  # first boundary

    sec_boundaries = {letter: start for letter, _, _ in SECTIONS
                      for letter, start in [(letter, sec_start[letter])]}

    # flatten boundary list
    boundaries = sorted(sec_start.values())
    boundary_to_sec = {v: k for k, v in sec_start.items()}
    sec_meta = {letter: (title, q_range) for letter, title, q_range in SECTIONS}

    for num, stem, opts, ans_letter, expl in questions:
        if num in boundary_to_sec:
            letter = boundary_to_sec[num]
            title, q_range = sec_meta[letter]
            story.append(section_block(letter, title, q_range))
            story.append(Spacer(1, 0.25*cm))

        story.append(question_block(num, stem, opts, ans_letter, expl))

    doc.build(story,
              onFirstPage=on_first_page,
              onLaterPages=on_later_pages)
    print(f"PDF saved to: {OUTPUT}")


if __name__ == "__main__":
    build()

cd /home/daytona/workspace/mcq-exam && python3 generate_mcq_pdf.py 2>&1

ls -lh /home/daytona/workspace/mcq-exam/Moore_COA_100_MCQs.pdf

mkdir -p /home/daytona/workspace/guyton-mcq && python3 -c "from reportlab.lib.pa…

~/guyton-mcq/build_pdf.py

from reportlab.lib.pagesizes import A4
from reportlab.lib.styles import getSampleStyleSheet, ParagraphStyle
from reportlab.lib.units import cm
from reportlab.lib import colors
from reportlab.platypus import (
    SimpleDocTemplate, Paragraph, Spacer, HRFlowable,
    KeepTogether, Table, TableStyle
)
from reportlab.lib.enums import TA_LEFT, TA_CENTER, TA_JUSTIFY

OUTPUT = "/home/daytona/workspace/guyton-mcq/Guyton_Hall_100_MCQs.pdf"

DARK = colors.HexColor("#1B3A5C")
MID  = colors.HexColor("#2E6DA4")
LITE = colors.HexColor("#D6E8F7")
GRN  = colors.HexColor("#27AE60")
GBG  = colors.HexColor("#EAF4EA")
GREY = colors.HexColor("#CCCCCC")
W    = colors.white
BLK  = colors.black

ss = getSampleStyleSheet()

def sty(name,**kw):
    p=ParagraphStyle(name,parent=ss["Normal"],**kw)
    return p

SEC_S  = sty("sec", fontSize=12, textColor=W, fontName="Helvetica-Bold",
             spaceBefore=12, spaceAfter=4, leading=16, leftIndent=0)
QN_S   = sty("qn",  fontSize=10, textColor=MID, fontName="Helvetica-Bold",
             spaceBefore=0, spaceAfter=0)
QT_S   = sty("qt",  fontSize=10.5, textColor=BLK, fontName="Helvetica-Bold",
             spaceBefore=0, spaceAfter=4, leading=15)
OPT_S  = sty("opt", fontSize=10, textColor=colors.HexColor("#222222"),
             fontName="Helvetica", leading=14, leftIndent=12,
             spaceBefore=1, spaceAfter=1)
AL_S   = sty("al",  fontSize=9.5, textColor=GRN, fontName="Helvetica-Bold",
             spaceBefore=4, spaceAfter=1)
AT_S   = sty("at",  fontSize=9, textColor=colors.HexColor("#1A1A1A"),
             fontName="Helvetica", leading=13, alignment=TA_JUSTIFY,
             spaceBefore=0, spaceAfter=6)
INSTR_S= sty("ins", fontSize=9, textColor=DARK, fontName="Helvetica",
             leading=13)

def sec_block(ltr, title, rng):
    lbl = f"SECTION {ltr}  |  {title}  (Q{rng})"
    t = Table([[Paragraph(lbl, SEC_S)]], colWidths=[17*cm])
    t.setStyle(TableStyle([
        ("BACKGROUND",(0,0),(-1,-1),DARK),
        ("TOPPADDING",(0,0),(-1,-1),7),("BOTTOMPADDING",(0,0),(-1,-1),7),
        ("LEFTPADDING",(0,0),(-1,-1),10),
    ]))
    return t

def qblock(num, stem, opts, ans, expl):
    elems = [
        Paragraph(f"Q{num}.", QN_S),
        Paragraph(stem, QT_S),
    ]
    for i,o in enumerate(opts):
        elems.append(Paragraph(f"<b>{'ABCD'[i]}.</b>  {o}", OPT_S))
    ans_t = Table([[Paragraph(f"&#10004;  Answer: {ans}", AL_S)],
                   [Paragraph(expl, AT_S)]], colWidths=[16.4*cm])
    ans_t.setStyle(TableStyle([
        ("BACKGROUND",(0,0),(-1,-1),GBG),
        ("LINEBEFORE",(0,0),(0,-1),3,GRN),
        ("LINEAFTER",(0,0),(0,-1),.5,GRN),
        ("LINEABOVE",(0,0),(-1,0),.5,GRN),
        ("LINEBELOW",(0,-1),(-1,-1),.5,GRN),
        ("TOPPADDING",(0,0),(-1,-1),5),("BOTTOMPADDING",(0,0),(-1,-1),5),
        ("LEFTPADDING",(0,0),(-1,-1),8),("RIGHTPADDING",(0,0),(-1,-1),6),
    ]))
    elems += [Spacer(1,4), ans_t, Spacer(1,8),
              HRFlowable(width="100%",thickness=0.4,color=GREY)]
    return KeepTogether(elems)

# ── page callbacks ──────────────────────────────────────────────────────────
def first_page(canvas, doc):
    canvas.saveState()
    pw, ph = A4
    canvas.setFillColor(DARK)
    canvas.rect(0, ph-135, pw, 135, fill=1, stroke=0)
    canvas.setFont("Helvetica-Bold", 20); canvas.setFillColor(W)
    canvas.drawCentredString(pw/2, ph-46, "MBBS FINAL EXAMINATION PREPARATION")
    canvas.setFont("Helvetica-Bold", 13)
    canvas.drawCentredString(pw/2, ph-68, "100 Multiple Choice Questions – Medical Physiology")
    canvas.setFont("Helvetica", 10); canvas.setFillColor(LITE)
    canvas.drawCentredString(pw/2, ph-88, "Reference: Guyton and Hall Textbook of Medical Physiology, 13th Edition")
    canvas.drawCentredString(pw/2, ph-106,
        "Cardiovascular & Respiratory Physiology | Autonomic Nervous System | Gas Exchange | Regulation of Respiration")
    _foot(canvas, doc); canvas.restoreState()

def later_pages(canvas, doc):
    canvas.saveState()
    pw, ph = A4
    canvas.setFillColor(DARK)
    canvas.rect(0, ph-26, pw, 26, fill=1, stroke=0)
    canvas.setFont("Helvetica-Bold", 8); canvas.setFillColor(W)
    canvas.drawString(2*cm, ph-17, "MBBS Final – Guyton & Hall 100 MCQs")
    canvas.drawRightString(pw-2*cm, ph-17, "Guyton and Hall Medical Physiology, 13th Ed.")
    _foot(canvas, doc); canvas.restoreState()

def _foot(canvas, doc):
    pw, _ = A4
    canvas.setFont("Helvetica", 8); canvas.setFillColor(colors.HexColor("#666666"))
    canvas.drawCentredString(pw/2, 1.0*cm, f"Page {doc.page}")
    canvas.setFillColor(GREY)
    canvas.line(2*cm, 1.4*cm, pw-2*cm, 1.4*cm)

# ══════════════════════════════════════════════════════════════════════════════
# ALL 100 QUESTIONS
# ══════════════════════════════════════════════════════════════════════════════
questions = [

# ─── SECTION A: Nervous Regulation, Autonomic NS, Sympathetic Vasoconstrictor,
#               Rapid Control of Arterial Pressure, Negative Feedback Reflexes (Q1–13)
(1,
"The vasomotor center, which controls sympathetic vasoconstrictor tone, is located in which part of the brain?",
["Cerebral cortex","Reticular substance of the medulla oblongata and lower one third of the pons",
 "Hypothalamus","Cerebellar cortex"],
"B",
"Per Guyton & Hall (Ch. 17), the vasomotor center lies in the reticular substance of the medulla oblongata and lower pons. It transmits signals through the spinal cord and then through sympathetic vasoconstrictor fibers to almost all blood vessels of the body."),

(2,
"Sympathetic stimulation of blood vessels causes vasoconstriction primarily through which receptor?",
["Beta-1 adrenergic receptors","Alpha-1 adrenergic receptors",
 "Muscarinic receptors","Beta-2 adrenergic receptors"],
"B",
"Norepinephrine released from sympathetic vasoconstrictor fibers binds predominantly to alpha-1 adrenergic receptors on vascular smooth muscle, causing vasoconstriction and an increase in peripheral resistance. Beta-2 receptors in skeletal muscle vessels cause vasodilation with epinephrine."),

(3,
"The basal rate of sympathetic vasoconstrictor tone to blood vessels is approximately:",
["0.5 impulses/second","1–2 impulses/second",
 "5–10 impulses/second","20 impulses/second"],
"B",
"Guyton & Hall states that the vasomotor center normally transmits signals at a rate of 1–2 impulses per second, maintaining a state of partial constriction (vasomotor tone). At maximum sympathetic stimulation, the rate rises to 10–20/sec; complete inhibition causes maximal vasodilation."),

(4,
"A 30-year-old man suddenly stands from a lying position. His arterial pressure transiently falls. The reflex that most rapidly corrects this is:",
["The chemoreceptor reflex","The baroreceptor (pressoreceptor) reflex",
 "The Cushing reaction","The CNS ischemic response"],
"B",
"The arterial baroreceptor reflex (negative feedback) is the most important rapid mechanism for buffering arterial pressure changes. Baroreceptors in the carotid sinus and aortic arch sense the pressure drop and immediately increase sympathetic output and decrease parasympathetic output, restoring pressure within seconds."),

(5,
"Baroreceptors are most sensitive to changes in arterial pressure in which range?",
["0–50 mmHg","60–180 mmHg (highest sensitivity around 100 mmHg)",
 "180–250 mmHg","Above 250 mmHg"],
"B",
"The baroreceptors respond most actively in the range of 60–180 mmHg, with peak sensitivity near the normal mean arterial pressure of ~100 mmHg. Below 60 mmHg or above 180 mmHg, the receptors are near their minimum or maximum firing rates and become less effective buffers."),

(6,
"The Cushing reaction (CNS ischemic response) is triggered by:",
["A fall in arterial PO2 below 80 mmHg","A rise in intracranial pressure that compresses cerebral vessels, reducing cerebral blood flow",
 "Stimulation of arterial baroreceptors","Stimulation of carotid body chemoreceptors"],
"B",
"The CNS ischemic response (Cushing reaction) is triggered when cerebral blood flow falls critically (usually when mean arterial pressure drops below ~60 mmHg or ICP rises markedly). The resulting CO2 and H+ accumulation in the vasomotor center causes an extreme sympathetic discharge, raising arterial pressure to very high levels."),

(7,
"Which of the following is a 'negative feedback' mechanism for arterial pressure control?",
["The positive feedback of cardiac failure","The baroreceptor reflex, which opposes the change that triggered it",
 "The Cushing reaction","Autoregulation of local blood flow"],
"B",
"Negative feedback means the response opposes the initial change: when pressure rises, baroreceptors increase their firing rate, which reduces sympathetic tone and lowers pressure back toward normal. The Cushing reaction is an emergency positive-pressure-raising mechanism, not a negative feedback stabilizer."),

(8,
"Norepinephrine is to sympathetic vasoconstriction as acetylcholine is to:",
["Sympathetic vasodilation in skeletal muscle","Parasympathetic vasodilation (e.g., in salivary glands and erectile tissue)",
 "Baroreceptor activation","Chemoreceptor stimulation"],
"B",
"Acetylcholine released by parasympathetic (cholinergic) vasodilator fibers produces vasodilation in certain tissues (salivary glands, erectile tissue, some cerebral vessels). Some sympathetic fibers to skeletal muscle also release ACh causing active vasodilation during exercise anticipation."),

(9,
"A patient receives a drug that blocks alpha-1 adrenergic receptors. The expected immediate cardiovascular effect is:",
["Bradycardia and hypertension","Vasodilation and a fall in arterial pressure; reflex tachycardia",
 "Vasoconstriction and hypertension","No effect on blood pressure"],
"B",
"Alpha-1 blockade removes sympathetic vasoconstrictor tone, causing arteriolar dilation and a drop in peripheral resistance and arterial pressure. The baroreceptor reflex detects the fall and triggers a reflex tachycardia and increased cardiac contractility to compensate."),

(10,
"The chemoreceptor reflex contributes to blood pressure control primarily when:",
["Arterial pressure is normal","Arterial oxygen saturation is above 95%",
 "Arterial pressure falls below ~80 mmHg, causing hypoxia and CO2 accumulation in chemoreceptors",
 "Heart rate exceeds 100 bpm"],
"C",
"The peripheral chemoreceptors (carotid and aortic bodies) and central chemoreceptors are stimulated by low PO2, high PCO2, and low pH. When arterial pressure falls enough to reduce chemoreceptor blood flow, the resulting hypoxia and hypercapnia stimulate the vasomotor center, causing powerful vasoconstriction."),

(11,
"In the atrial (low-pressure) reflex, distension of the atria primarily causes:",
["Vasoconstriction and hypertension","Reflex decrease in heart rate (Bainbridge reflex at low filling pressures) or reflex tachycardia at high filling, plus inhibition of ADH release",
 "Parasympathetic vasoconstriction","Activation of baroreceptors"],
"B",
"Stretch receptors in the atrial walls signal volume status. At high filling, they inhibit ADH (antidiuretic hormone) release, promoting diuresis and reducing blood volume. They also trigger the Bainbridge reflex (tachycardia at high filling rates) to increase cardiac output and prevent venous congestion."),

(12,
"During the 'defense reaction' (alerting response), sympathetic activation causes which vascular pattern?",
["Vasoconstriction everywhere including skeletal muscle","Vasoconstriction in the skin and splanchnic beds; vasodilation in skeletal muscle and heart",
 "Vasodilation everywhere","Vasoconstriction in the heart only"],
"B",
"The defense reaction (mediated by the hypothalamus and higher cortical areas) prepares the body for 'fight or flight': blood is redistributed away from skin and gut (vasoconstriction) toward skeletal muscle, heart, and brain (vasodilation via sympathetic cholinergic and beta-2 adrenergic mechanisms)."),

(13,
"A patient has a lesion in the rostral ventrolateral medulla (RVLM). The expected effect on arterial pressure is:",
["Severe hypertension","Severe hypotension due to loss of tonic sympathetic vasoconstrictor drive",
 "No change","Intermittent hypertension"],
"B",
"The RVLM is the primary pressor region of the vasomotor center, providing tonic sympathetic excitatory drive to peripheral blood vessels and the heart. Lesions in this region cause profound hypotension because the tonic sympathetic vasoconstrictor signals are abolished."),

# ─── SECTION B: Kidneys, Long-Term Pressure Control, RAAS, Hypertension (Q14–26)
(14,
"The renal-body fluid feedback mechanism controls long-term arterial pressure primarily by:",
["Adjusting peripheral resistance acutely","Regulating sodium and water excretion to alter blood volume and cardiac output",
 "Releasing renin in response to exercise","Modulating baroreceptor sensitivity"],
"B",
"Guyton & Hall emphasizes that the kidney is the dominant long-term regulator of arterial pressure. When pressure rises, renal output of sodium and water increases (pressure natriuresis and diuresis), reducing blood volume and cardiac output until pressure returns to normal."),

(15,
"The concept of 'pressure natriuresis' refers to:",
["Decreased renal sodium excretion when arterial pressure rises","Increased renal sodium and water excretion in response to a rise in arterial pressure",
 "Activation of RAAS when pressure falls","Sympathetic vasoconstriction of renal vessels"],
"B",
"Pressure natriuresis: when arterial pressure rises, the kidneys excrete more sodium and water, reducing extracellular fluid volume, venous return, cardiac output, and eventually arterial pressure. This is the cornerstone of Guyton's infinite-gain concept for long-term pressure control."),

(16,
"Renin is secreted by which cells of the kidney?",
["Mesangial cells of the glomerulus","Juxtaglomerular (JG) cells of the afferent arteriole",
 "Principal cells of the collecting duct","Macula densa cells"],
"B",
"Renin is synthesized and secreted by juxtaglomerular (JG) cells (granular cells) located in the wall of the afferent arteriole near the macula densa. Stimuli for renin release include decreased renal perfusion pressure, decreased sodium delivery to the macula densa, and sympathetic stimulation (beta-1 receptors)."),

(17,
"Angiotensin II causes hypertension through which mechanisms? (Choose the MOST COMPLETE answer)",
["Only direct vasoconstriction","Direct arteriolar vasoconstriction + stimulation of aldosterone secretion (Na/water retention) + increased thirst + ADH release + direct tubular sodium retention",
 "Only aldosterone stimulation","Only ADH release"],
"B",
"Angiotensin II is a powerful pressor agent: it directly constricts arterioles, stimulates the adrenal cortex to secrete aldosterone (promoting Na+ and water reabsorption), stimulates ADH release, increases thirst, and directly acts on renal tubules to enhance sodium reabsorption – all raising arterial pressure."),

(18,
"A patient is found to have a renin-secreting tumor of the juxtaglomerular cells. The expected laboratory findings are:",
["High renin, low angiotensin II, low aldosterone, low BP","High renin, high angiotensin II, high aldosterone, severe hypertension",
 "Low renin, high aldosterone, hypertension","High renin, low aldosterone, hypotension"],
"B",
"A renin-secreting JG cell tumor produces excess renin → excess angiotensin II → excess aldosterone. The result is severe hypertension with high plasma renin activity, high angiotensin II, high aldosterone, hypokalemia, and metabolic alkalosis. Treatment is surgical excision."),

(19,
"Renovascular hypertension (two-kidney Goldblatt hypertension) is caused by:",
["Excess aldosterone from both adrenal glands","Renal artery stenosis reducing renal perfusion pressure, activating RAAS and causing hypertension",
 "High salt diet suppressing RAAS","Bilateral renal agenesis"],
"B",
"Clamping (stenosis) of one renal artery reduces perfusion pressure in that kidney, causing excess renin release and angiotensin II formation. This raises systemic arterial pressure while the contralateral kidney excretes excess salt/water. The result is RAAS-mediated hypertension (Goldblatt 2-kidney model)."),

(20,
"In primary (essential) hypertension, which physiological abnormality is most consistently found?",
["Permanently elevated cardiac output","A rightward shift in the pressure-natriuresis curve, requiring higher arterial pressure to excrete a normal sodium load",
 "Low peripheral resistance","Low renin activity in all patients"],
"B",
"Guyton's model of essential hypertension centers on an abnormal kidney that requires a higher-than-normal arterial pressure to excrete a normal sodium load (rightward shift of the pressure-natriuresis curve). This means the kidney 'sets' the long-term pressure at a higher level."),

(21,
"Aldosterone causes hypertension primarily by acting on:",
["Vascular smooth muscle directly","Principal cells of the cortical collecting duct to increase Na+ reabsorption and K+ secretion, expanding extracellular fluid volume",
 "Mesangial cells","The JG apparatus to increase renin secretion"],
"B",
"Aldosterone binds to mineralocorticoid receptors in the principal cells of the cortical collecting duct, increasing the number of Na+/K+-ATPase pumps and ENaC (epithelial sodium channels), promoting sodium and water retention, expanding blood volume, and raising arterial pressure."),

(22,
"An ACE inhibitor (e.g., lisinopril) lowers blood pressure primarily by:",
["Blocking alpha-1 adrenergic receptors","Inhibiting conversion of angiotensin I to angiotensin II, reducing vasoconstriction and aldosterone secretion",
 "Blocking calcium channels","Increasing renin secretion"],
"B",
"ACE (angiotensin-converting enzyme) converts angiotensin I to the active angiotensin II. ACE inhibitors block this step, reducing angiotensin II levels. This causes arteriolar dilation (lower peripheral resistance), reduced aldosterone (less Na+ retention), and lower blood pressure. Plasma renin rises due to loss of feedback."),

(23,
"The infinite-gain concept in arterial pressure regulation by the kidneys means:",
["The kidneys can only modestly correct pressure changes","As long as the kidneys are functioning normally, they can eventually return arterial pressure exactly to the normal set-point, regardless of other pressure-raising influences",
 "The kidneys lose their regulatory capacity when pressure is very high","Pressure regulation by the kidney is limited to ±10 mmHg"],
"C",
"Guyton's infinite-gain concept states that because the kidney never reaches a point where it stops responding to pressure changes, it can achieve perfect long-term pressure regulation – returning pressure precisely to its set-point. This is why the kidney is called the dominant long-term pressure controller."),

(24,
"A patient with chronic renal failure develops hypertension. The primary mechanism is:",
["Excess renin secretion only","Impaired pressure natriuresis causing sodium and water retention, expanding blood volume and raising cardiac output",
 "Excess aldosterone from the adrenal gland","Sympathetic overactivation only"],
"B",
"In chronic renal failure, the damaged kidneys cannot excrete sodium and water normally at a given arterial pressure. The resulting fluid retention expands blood volume and raises cardiac output and, through autoregulation, peripheral resistance – both elevating arterial pressure."),

(25,
"Which is the correct sequence of the RAAS?",
["Renin → Angiotensin II → Angiotensin I → Aldosterone","Angiotensinogen → (renin) → Angiotensin I → (ACE) → Angiotensin II → Aldosterone secretion",
 "Angiotensin II → (renin) → Angiotensin I → Aldosterone","ACE → Renin → Angiotensin I → Aldosterone"],
"B",
"The correct sequence: Angiotensinogen (from liver) is cleaved by renin → Angiotensin I (inactive decapeptide) → Angiotensin-converting enzyme (lung) cleaves 2 amino acids → Angiotensin II (active octapeptide) → stimulates adrenal cortex to secrete aldosterone."),

(26,
"Primary hyperaldosteronism (Conn's syndrome) is characterized by:",
["High renin, high aldosterone, hypokalemia","Low renin, high aldosterone, hypertension, hypokalemia, metabolic alkalosis",
 "High renin, low aldosterone, hyperkalemia","Low renin, low aldosterone, hypotension"],
"B",
"In Conn's syndrome (adrenal adenoma secreting aldosterone autonomously), aldosterone is high, suppressing renin. Features: hypertension, hypokalemia (due to excess K+ secretion in collecting duct), metabolic alkalosis, low serum renin activity, and muscle weakness."),

# ─── SECTION C: Muscle Blood Flow, Cardiac Output in Exercise,
#               Coronary Circulation, Cardiac Failure, Circulatory Shock (Q27–39)
(27,
"During heavy exercise, muscle blood flow can increase up to how many times the resting value?",
["2–3 times","15–25 times",
 "5–7 times","30–40 times"],
"B",
"Guyton & Hall states that during maximal exercise, skeletal muscle blood flow can increase from ~3–4 mL/min/100g at rest to ~50–80 mL/min/100g – an increase of 15–25 times – driven primarily by local metabolic vasodilators (adenosine, CO2, K+, lactic acid, low O2)."),

(28,
"The primary factor responsible for vasodilation in exercising skeletal muscle is:",
["Sympathetic cholinergic vasodilator nerves","Local metabolic factors including decreased O2, increased CO2, H+, K+, adenosine, and lactic acid",
 "Circulating epinephrine alone","Parasympathetic vasodilation"],
"B",
"While sympathetic withdrawal and circulating epinephrine contribute, the dominant mechanism of exercise hyperemia in skeletal muscle is local metabolic autoregulation. The accumulation of vasodilator metabolites (adenosine, K+, CO2, lactate, H+) relaxes arteriolar smooth muscle in proportion to metabolic activity."),

(29,
"During maximal exercise, cardiac output in a trained athlete may reach:",
["5 L/min","25–35 L/min",
 "10 L/min","40–50 L/min"],
"B",
"Cardiac output at rest is approximately 5 L/min. During maximal exercise, it can reach 20–25 L/min in healthy adults and 25–35 L/min in highly trained athletes, driven by increased heart rate, increased stroke volume (Frank-Starling mechanism), and reduced total peripheral resistance in exercising muscle."),

(30,
"The left coronary artery supplies blood to the myocardium mainly during which phase of the cardiac cycle?",
["Systole only","Diastole, because systolic contraction compresses intramyocardial vessels, severely limiting flow",
 "Equally throughout systole and diastole","Neither systole nor diastole"],
"B",
"Left coronary blood flow is markedly reduced during systole because the high intramyocardial pressure compresses coronary vessels. During diastole (when the heart relaxes), the coronary vessels open and 70–80% of left coronary flow occurs. Right coronary flow is less affected because the right ventricle generates lower pressures."),

(31,
"Angina pectoris occurs when:",
["Coronary blood flow exceeds myocardial oxygen demand","Myocardial oxygen demand exceeds coronary supply, usually due to atherosclerotic narrowing",
 "Heart rate drops below 50 bpm","Cardiac output is too high"],
"B",
"Angina pectoris is ischemic chest pain caused by insufficient coronary blood supply relative to myocardial oxygen demand. Typically caused by coronary artery atherosclerosis narrowing the vessel lumen. The ischemic myocardium releases substances (adenosine, bradykinin, K+) that stimulate cardiac pain fibers (afferent C fibers in T1–T4 sympathetic nerves)."),

(32,
"The primary difference between systolic and diastolic heart failure is:",
["Systolic failure has a high ejection fraction; diastolic failure has a low ejection fraction","Systolic failure has a reduced ejection fraction (EF <40%); diastolic failure has a preserved EF but impaired ventricular filling",
 "They are identical conditions","Diastolic failure involves the right ventricle only"],
"B",
"In systolic (HFrEF) heart failure, the ventricle contracts poorly (reduced EF <40%). In diastolic (HFpEF) heart failure, the ventricle is stiff and fills poorly despite normal ejection fraction (≥50%). Both cause symptoms of congestion and reduced exercise tolerance."),

(33,
"In cardiac failure, the sympathetic nervous system is activated. This is initially compensatory but becomes harmful because:",
["It decreases heart rate","Chronic sympathetic activation causes tachycardia, increased afterload, ventricular remodeling, and cardiomyocyte apoptosis – worsening the failure over time",
 "It causes vasodilation","It suppresses the RAAS"],
"B",
"Sympathetic activation in heart failure initially compensates by increasing heart rate and contractility. However, chronic activation causes sustained vasoconstriction (increasing afterload), pathological ventricular hypertrophy and remodeling, beta-receptor downregulation, and cardiomyocyte apoptosis – all of which worsen cardiac function."),

(34,
"The main physiological cause of cardiogenic shock is:",
["Excessive vasodilation","Severely reduced cardiac output due to myocardial failure (e.g., massive MI), leading to inadequate tissue perfusion",
 "Blood volume loss","Anaphylaxis"],
"B",
"Cardiogenic shock results from pump failure – the heart cannot maintain adequate cardiac output to perfuse vital organs. The most common cause is massive myocardial infarction. Features: hypotension, cold clammy skin, reduced urine output, elevated PCWP, and low cardiac output despite high preload."),

(35,
"In hypovolemic shock, the compensatory mechanisms include all of the following EXCEPT:",
["Sympathetic vasoconstriction","Increased ADH and aldosterone secretion","Renin-angiotensin activation",
 "Vasodilation and decreased heart rate"],
"D",
"Hypovolemic shock triggers: intense sympathetic vasoconstriction, tachycardia, ADH release (water retention), RAAS activation (Na+ and water retention), and transcapillary refill. Vasodilation and bradycardia would worsen shock – these are NOT compensatory responses."),

(36,
"The 'non-progressive' (compensated) stage of shock is characterized by:",
["Irreversible organ damage","Compensatory mechanisms maintaining tissue perfusion; the patient recovers if the underlying cause is treated",
 "Progressive deterioration despite treatment","Cardiac arrest"],
"B",
"Guyton & Hall describes three stages of shock: (1) non-progressive (compensated) – normal feedback mechanisms can restore homeostasis; (2) progressive – positive feedback worsens shock; (3) irreversible – so much cellular damage has occurred that the patient will die regardless of therapy."),

(37,
"A 50-year-old man develops anaphylactic shock after a penicillin injection. The primary hemodynamic mechanism is:",
["Cardiac muscle failure","Massive histamine-mediated vasodilation and increased vascular permeability causing distributive shock",
 "Blood loss","Tension pneumothorax with obstructed venous return"],
"B",
"Anaphylactic (distributive) shock results from massive release of histamine and other mediators causing extreme arteriolar dilation, venous dilation, and increased capillary permeability. The result is a precipitous fall in systemic vascular resistance and effective circulating volume, leading to profound hypotension."),

(38,
"Adenosine plays an important role in coronary autoregulation because:",
["It is a potent vasoconstrictor","It is released by ischemic myocardium and is a powerful coronary vasodilator, matching blood flow to metabolic demand",
 "It increases myocardial contractility","It activates the RAAS"],
"B",
"When myocardial oxygen demand exceeds supply, ATP is broken down to AMP and then adenosine. Adenosine diffuses to adjacent coronary arterioles where it binds A2 receptors and causes powerful vasodilation, increasing coronary blood flow to match demand – a key local autoregulatory mechanism."),

(39,
"In forward failure of the heart, the main consequence is:",
["Pulmonary edema only","Inadequate cardiac output causing reduced perfusion of tissues (fatigue, reduced renal function, hypotension)",
 "Peripheral edema only","Bradycardia"],
"B",
"Forward failure refers to inadequate forward pumping of blood into the systemic circulation. Features include: reduced cardiac output, fatigue, exercise intolerance, pre-renal azotemia (reduced GFR), and in severe cases, hypotension and cardiogenic shock."),

# ─── SECTION D: Pulmonary Ventilation, Pleural Pressure, Compliance,
#               Surfactant, Volumes, Dead Space (Q40–52)
(40,
"The intrapleural (intrathoracic) pressure at rest (end-expiration) is approximately:",
["+5 mmHg (above atmospheric)","-5 mmHg (subatmospheric/negative)",
 "0 mmHg (equal to atmospheric)","−20 mmHg"],
"B",
"The intrapleural pressure at the end of quiet expiration is approximately −5 cmH2O (about −3.7 mmHg). This subatmospheric pressure results from the opposing elastic recoil of the lungs (pulling inward) and the chest wall (pulling outward) and keeps the lungs inflated."),

(41,
"During quiet inspiration, intrapleural pressure changes from −5 to approximately:",
["−2 cmH2O","−8 cmH2O",
 "+2 cmH2O","−20 cmH2O"],
"B",
"During quiet inspiration, the diaphragm and intercostal muscles contract, expanding the thoracic cavity. This causes intrapleural pressure to fall from approximately −5 cmH2O to −8 cmH2O, creating a pressure gradient that draws air into the lungs."),

(42,
"Lung compliance is defined as:",
["The pressure required to maintain lung inflation","The change in lung volume per unit change in transmural pressure (ΔV/ΔP)",
 "The elasticity of lung tissue","The resistance to airflow in the airways"],
"B",
"Lung compliance (C = ΔV/ΔP) measures the ease of lung expansion: how much the lungs expand per unit increase in transmural pressure. Normal lung compliance is approximately 200 mL/cmH2O. Decreased compliance (stiff lungs) is seen in fibrosis and ARDS; increased compliance in emphysema."),

(43,
"Pulmonary surfactant reduces surface tension in the alveoli. It is produced by which cells?",
["Type I pneumocytes","Type II pneumocytes (granular pneumocytes)",
 "Alveolar macrophages","Club (Clara) cells"],
"B",
"Type II pneumocytes (granular pneumocytes) synthesize and secrete pulmonary surfactant, a lipoprotein complex rich in dipalmitoylphosphatidylcholine (DPPC). Surfactant reduces alveolar surface tension, preventing alveolar collapse and reducing the work of breathing."),

(44,
"According to the Law of Laplace (P = 2T/r), a smaller alveolus without surfactant would:",
["Have lower pressure than a larger alveolus","Have higher pressure than a larger alveolus and tend to empty into it (causing atelectasis)",
 "Have the same pressure","Have negative pressure"],
"B",
"Laplace's law: P = 2T/r. For a given surface tension, smaller radius → higher pressure. Without surfactant, small alveoli would have higher pressure and tend to empty into larger ones (causing alveolar collapse/atelectasis). Surfactant lowers T proportionally more in small alveoli, equalizing pressures."),

(45,
"The functional residual capacity (FRC) is the volume of air remaining in the lungs after:",
["A maximal inspiration","A normal quiet expiration",
 "A maximal expiration","A forced expiration"],
"B",
"FRC = ERV + RV. It is the volume of air remaining in the lungs at the end of a normal, quiet expiration, when the respiratory muscles are relaxed. FRC represents the equilibrium point where the inward elastic recoil of the lungs equals the outward recoil of the chest wall. Normal FRC ≈ 2.3 L."),

(46,
"The residual volume (RV) cannot be measured by simple spirometry because:",
["It is too small to measure","It is the volume that cannot be exhaled even with maximal effort, so the spirometer bell never records it",
 "Spirometry only measures inspiratory volumes","The patient cannot hold their breath long enough"],
"B",
"RV (~1.2 L) is the volume remaining in the lungs after maximal forced expiration. It cannot be measured by spirometry because the subject cannot exhale this air – the lungs can never be completely emptied. RV (and FRC, TLC) are measured by helium dilution, nitrogen washout, or body plethysmography."),

(47,
"Anatomical dead space refers to:",
["Alveoli that are perfused but not ventilated","The volume of conducting airways (nose to terminal bronchioles) that do not participate in gas exchange – approximately 150 mL",
 "Alveoli that are ventilated but not perfused","The volume of the pleural space"],
"B",
"Anatomical dead space (~150 mL in an average adult) includes all conducting airways from the nose/mouth down to the terminal bronchioles. No gas exchange occurs here. Physiological dead space = anatomical dead space + alveolar dead space (unperfused alveoli)."),

(48,
"If tidal volume is 500 mL and anatomical dead space is 150 mL, alveolar ventilation per breath is:",
["500 mL","350 mL",
 "150 mL","650 mL"],
"B",
"Alveolar ventilation per breath = Tidal volume − Dead space = 500 − 150 = 350 mL. At a respiratory rate of 12/min, alveolar ventilation = 350 × 12 = 4,200 mL/min. This is the volume that actually reaches the alveoli and participates in gas exchange."),

(49,
"A patient breathes shallowly at 25 breaths/min with a tidal volume of 200 mL (dead space 150 mL). Alveolar ventilation is:",
["25 × 200 = 5,000 mL/min","25 × (200−150) = 1,250 mL/min",
 "25 × 150 = 3,750 mL/min","25 × 350 = 8,750 mL/min"],
"B",
"Alveolar ventilation = RR × (VT − VD) = 25 × (200−150) = 25 × 50 = 1,250 mL/min. Shallow rapid breathing markedly reduces effective alveolar ventilation because a large fraction of each breath is wasted ventilating dead space. This is a key clinical concept – increasing rate alone without increasing depth is inefficient."),

(50,
"The primary function of the mucociliary escalator in the respiratory tract is:",
["Gas exchange","Trapping and clearing inhaled particles and microorganisms by beating cilia propelling mucus toward the pharynx",
 "Warming and humidifying air","Producing surfactant"],
"B",
"The mucociliary escalator is the lung's primary defense mechanism: goblet cells and submucosal glands secrete mucus that traps particles/pathogens; cilia beat at ~1,000 strokes/min propelling the mucus blanket upward toward the pharynx where it is swallowed or expectorated. Smoking paralyzes cilia, impairing this defense."),

(51,
"In restrictive lung disease (e.g., pulmonary fibrosis), the expected spirometric finding is:",
["Reduced FEV1/FVC ratio","Proportionally reduced FVC and FEV1 with a normal or increased FEV1/FVC ratio",
 "Increased TLC","Air trapping with elevated RV"],
"B",
"Restrictive disease reduces all lung volumes (TLC, FVC, FEV1) proportionally because of stiff lungs or chest wall restriction. The FEV1/FVC ratio is normal (>70%) or even elevated because the stiff lungs recoil forcefully. Air trapping and increased RV are features of obstructive disease, not restrictive."),

(52,
"The 'closing capacity' exceeds FRC in elderly patients. This means:",
["Airways close during maximal inspiration","Small airways close during tidal breathing, causing gas trapping and V/Q mismatch – explaining increased hypoxemia in the elderly",
 "FRC increases with age","Lung compliance increases with age"],
"B",
"Closing capacity is the lung volume at which small airways begin to close. Normally below FRC, so airways remain open during tidal breathing. With aging (or obesity), closing capacity exceeds FRC, meaning airways close during normal tidal breathing, trapping gas and causing ventilation-perfusion mismatch and hypoxemia."),

# ─── SECTION E: Pulmonary Circulation, Fluid Exchange, Pulmonary Edema,
#               Pleural Fluid (Q53–63)
(53,
"Normal mean pulmonary artery pressure is approximately:",
["25 mmHg","15 mmHg (systolic ~25, diastolic ~8)",
 "50 mmHg","5 mmHg"],
"B",
"Normal pulmonary artery pressure: systolic ~25 mmHg, diastolic ~8 mmHg, mean ~15 mmHg. This is about one-sixth of systemic arterial pressure. Pulmonary hypertension is defined as mean PAP >25 mmHg at rest. The low pressure is maintained by the high distensibility and low resistance of the pulmonary vasculature."),

(54,
"The pulmonary capillary wedge pressure (PCWP) reflects:",
["Pulmonary artery pressure","Left atrial pressure (and indirectly left ventricular end-diastolic pressure)",
 "Right atrial pressure","Aortic pressure"],
"B",
"PCWP is measured by wedging a balloon-tipped catheter in a small pulmonary artery, occluding forward flow. The resulting pressure reflects back to the left atrium. Normal PCWP is 6–12 mmHg. PCWP >18 mmHg suggests left heart failure; used to differentiate cardiogenic from non-cardiogenic pulmonary edema."),

(55,
"The distribution of blood flow in the lungs is primarily affected by:",
["Airway resistance","Gravity (hydrostatic pressure gradient) causing greater flow to the lung bases in an upright person",
 "Surfactant levels","Respiratory rate"],
"B",
"In the upright lung, gravity causes higher hydrostatic pressure at the bases, distending capillaries and increasing flow. West's zones model this: Zone 1 (apex) – alveolar pressure > arterial > venous (no flow); Zone 2 – arterial > alveolar > venous; Zone 3 (base) – arterial > venous > alveolar (most flow)."),

(56,
"The primary force driving fluid OUT of pulmonary capillaries is:",
["Capillary oncotic pressure","Capillary hydrostatic pressure (Starling force)",
 "Interstitial oncotic pressure","Alveolar surface tension"],
"B",
"Per Starling's forces, fluid filtration from pulmonary capillaries is driven primarily by capillary hydrostatic pressure (~7 mmHg). The opposing forces are plasma oncotic pressure (~28 mmHg) and interstitial fluid pressure (slightly negative). Net filtration is small, and lymphatics remove the excess."),

(57,
"Pulmonary edema occurs when:",
["Pulmonary blood flow is reduced","Fluid filtration from pulmonary capillaries exceeds lymphatic drainage capacity, usually when PCWP rises above ~25–30 mmHg",
 "Alveolar ventilation decreases","Surfactant production increases"],
"B",
"Pulmonary edema occurs when net filtration overwhelms lymphatic clearance. The 'safety factor' against pulmonary edema includes reduced interstitial fluid pressure, increased lymph flow, and dilution of interstitial proteins. When left atrial/PCWP rises above ~25–30 mmHg, this safety factor is overwhelmed and edema forms."),

(58,
"Hypoxic pulmonary vasoconstriction (HPV) serves what physiological function?",
["To cause pulmonary hypertension","To redirect blood flow away from poorly ventilated (hypoxic) lung segments toward better-ventilated areas, optimizing V/Q matching",
 "To increase pulmonary blood flow overall","To dilate the airways"],
"B",
"HPV is unique to the pulmonary circulation (opposite to systemic vessels which dilate with hypoxia). When alveolar O2 is low, local pulmonary arterioles constrict, diverting blood to better-ventilated areas. This reduces V/Q mismatch and maintains arterial oxygenation. Globally, HPV can cause pulmonary hypertension (e.g., at altitude)."),

(59,
"A patient with left ventricular failure develops dyspnoea. The mechanism involves:",
["Reduced pulmonary blood flow","Elevated left atrial pressure → elevated pulmonary venous pressure → pulmonary capillary hypertension → pulmonary edema → impaired gas exchange",
 "Bronchospasm only","Pleural effusion as the sole cause"],
"B",
"In LV failure, the left ventricle cannot empty properly, raising left atrial pressure. This backs up into the pulmonary veins and capillaries, elevating PCWP. When PCWP exceeds plasma oncotic pressure, fluid leaks into the interstitium and alveoli, causing pulmonary edema and dyspnoea."),

(60,
"Pleural fluid is normally produced and absorbed. The net direction of flow is:",
["Fluid is produced by the visceral pleura and absorbed by the parietal pleura","Fluid is produced by the parietal pleura (where hydrostatic pressure favors filtration) and absorbed primarily by lymphatics of the parietal pleura",
 "No net flow normally","Fluid flows from the pleural space into the lung"],
"B",
"Small amounts of pleural fluid (~15 mL total, 0.1 mL/kg) are continuously produced by filtration from parietal pleural capillaries and absorbed primarily by parietal pleural lymphatics (stomata). A small amount is also absorbed by the visceral pleura. Pleural effusion results when production exceeds absorption."),

(61,
"A transudative pleural effusion is caused by:",
["Infection of the pleura","Altered Starling forces – increased hydrostatic pressure (e.g., heart failure) or decreased oncotic pressure (e.g., hypoalbuminemia) – without pleural inflammation",
 "Malignancy directly","Tuberculosis"],
"B",
"Transudates result from systemic factors altering Starling forces (CHF, hypoalbuminemia, hepatic cirrhosis). Exudates result from local pleural disease increasing capillary permeability (pneumonia, malignancy, TB). Light's criteria distinguish the two."),

(62,
"In the apex of the upright lung (West's Zone 1), which pressure relationship exists?",
["Arterial > venous > alveolar","Alveolar > arterial > venous (blood flow is minimal or absent)",
 "Arterial > alveolar > venous","Venous > arterial > alveolar"],
"B",
"In Zone 1 (lung apex), alveolar pressure exceeds pulmonary arterial pressure (which is reduced by gravity at the apex). This collapses pulmonary capillaries and eliminates blood flow. Zone 1 normally barely exists; it becomes significant when alveolar pressure is raised (PEEP) or arterial pressure falls (hemorrhage)."),

(63,
"Non-cardiogenic pulmonary edema (ARDS) differs from cardiogenic pulmonary edema primarily in that:",
["PCWP is elevated in ARDS","PCWP is normal in ARDS; edema is caused by increased capillary permeability (damage to the alveolar-capillary membrane), not elevated hydrostatic pressure",
 "ARDS causes unilateral edema","ARDS is caused by left heart failure"],
"B",
"In ARDS, the alveolar-capillary barrier is damaged (sepsis, aspiration, trauma), causing protein-rich exudative edema despite a normal PCWP (<18 mmHg). In cardiogenic pulmonary edema, PCWP is elevated (>18 mmHg) and the barrier is intact. This distinction is critical for management."),

# ─── SECTION F: Gas Exchange, Partial Pressures, Diffusion,
#               V/Q Ratio, Physiological Shunt & Dead Space (Q64–75)
(64,
"Dalton's Law of partial pressures states that:",
["Total pressure of a gas mixture equals the product of individual pressures","The partial pressure of each gas in a mixture equals the total pressure multiplied by the fraction of that gas in the mixture",
 "Gas pressure is inversely proportional to volume","Partial pressures are equal in all gases"],
"B",
"Dalton's Law: P_gas = P_total × F_gas (fractional concentration). For oxygen in atmospheric air: PO2 = 760 × 0.21 = 159 mmHg. This principle underlies the calculation of alveolar, arterial, and venous gas partial pressures."),

(65,
"Normal alveolar PO2 (PAO2) at sea level is approximately:",
["159 mmHg (same as inspired air)","100 mmHg (after humidification and CO2 addition dilute inspired oxygen)",
 "40 mmHg","60 mmHg"],
"B",
"Although inspired PO2 is ~159 mmHg, alveolar PO2 is ~100 mmHg because: (1) humidification of inspired air (water vapour pressure 47 mmHg reduces the partial pressure of other gases); (2) continuous O2 uptake by blood; and (3) CO2 from blood (~40 mmHg) diluting alveolar gas."),

(66,
"The alveolar gas equation is: PAO2 = PiO2 − (PACO2/R). What does 'R' represent?",
["Resistance of the respiratory membrane","Respiratory exchange ratio (RQ) – the ratio of CO2 produced to O2 consumed (~0.8 on a mixed diet)",
 "Residual volume","Respiratory rate"],
"B",
"R is the respiratory exchange ratio (respiratory quotient, RQ). On a mixed diet RQ ≈ 0.8. The equation adjusts for the fact that not all O2 consumed is replaced by CO2 in the alveoli: PAO2 = 150 − (40/0.8) = 150 − 50 = 100 mmHg (approximately)."),

(67,
"The normal alveolar-arterial (A-a) oxygen gradient is approximately:",
["0 mmHg (no gradient)","5–10 mmHg in young adults (due to small normal physiological shunt and V/Q inequality)",
 "30–40 mmHg","50 mmHg"],
"B",
"The normal A-a gradient is approximately 5–10 mmHg in young adults on room air, caused by small physiological shunt (bronchial and thebesian veins, ~2% of cardiac output) and minor V/Q mismatch. The gradient widens with age and increases with lung disease, being useful in diagnosing causes of hypoxemia."),

(68,
"The primary factor that determines the rate of gas diffusion across the respiratory membrane is:",
["Airway resistance","The partial pressure difference (pressure gradient) for each gas, membrane thickness, and surface area (Fick's Law)",
 "Respiratory rate","Surfactant concentration"],
"B",
"Fick's Law of diffusion: Rate ∝ (ΔP × A × D) / T, where ΔP = partial pressure difference, A = surface area, T = thickness, D = diffusion coefficient. Conditions that reduce surface area (emphysema), increase thickness (fibrosis, pulmonary edema), or reduce ΔP (altitude) all impair gas exchange."),

(69,
"A V/Q ratio of 0 (zero) represents:",
["Normal ventilation-perfusion matching","A shunt – perfusion without ventilation (e.g., airway obstruction with continued blood flow)",
 "Dead space – ventilation without perfusion","Hyperventilation"],
"B",
"V/Q = 0 means there is perfusion but no ventilation (complete shunt). Blood passes through without gas exchange and exits with venous oxygen levels, causing hypoxemia. V/Q = infinity means ventilation but no perfusion (dead space). Normal V/Q ≈ 0.8 overall."),

(70,
"The physiological shunt refers to:",
["Anatomical right-to-left cardiac shunts only","The total venous admixture including anatomical shunts plus blood from alveoli with a V/Q of zero – i.e., all blood that bypasses effective gas exchange",
 "The dead space in the lungs","Blood flow through the bronchial arteries"],
"B",
"Physiological shunt (Qs/Qt) is the total fraction of cardiac output that does not exchange gases effectively with alveolar air. It includes: (1) anatomical shunts (bronchial veins, thebesian veins), (2) blood from totally unventilated alveoli (V/Q=0), and (3) regions with very low V/Q. It causes an A-a gradient that does NOT correct with 100% O2."),

(71,
"Physiological dead space (VD_phys) is greater than anatomical dead space because:",
["It includes the trachea","It includes the anatomical dead space PLUS alveolar dead space (well-ventilated but poorly perfused alveoli)",
 "It decreases with lung disease","It is only present in obstructive disease"],
"B",
"Physiological dead space = anatomical dead space + alveolar dead space. Alveolar dead space = well-ventilated alveoli with little or no perfusion (V/Q → infinity, e.g., pulmonary embolism). Normally alveolar dead space is minimal, so VD_phys ≈ VD_anat (~150 mL). In pulmonary embolism, VD_phys rises dramatically."),

(72,
"A patient has a pulmonary embolism. The primary effect on gas exchange is an increase in:",
["Physiological shunt","Physiological dead space – alveoli are ventilated but not perfused (V/Q = infinity)",
 "V/Q ratio in all regions","Diffusing capacity"],
"B",
"Pulmonary embolism obstructs blood flow to a lung segment. The affected alveoli continue to receive ventilation but no perfusion – creating alveolar dead space and increasing physiological dead space. The patient typically develops hypoxemia (due to reflex bronchoconstriction and eventual surfactant loss causing atelectasis/shunt) and hypocapnia (from compensatory hyperventilation)."),

(73,
"In a region of the lung with a high V/Q ratio (poorly perfused but well-ventilated), the alveolar gas composition would show:",
["Low PAO2 and high PACO2","High PAO2 (approaching inspired PO2) and low PACO2 (approaching inspired PCO2 ≈ 0)",
 "Normal PAO2 and normal PACO2","Low PAO2 and low PACO2"],
"B",
"With high V/Q (excess ventilation relative to perfusion), little CO2 is delivered from blood and O2 is not taken up efficiently. The alveolar gas approaches the composition of inspired air: high PO2 (~149 mmHg) and low PCO2 (~0 mmHg). This represents wasted ventilation (alveolar dead space)."),

(74,
"CO2 diffuses across the respiratory membrane approximately how much faster than O2?",
["At the same rate","About 20 times faster than O2 (due to its much higher solubility in lipid membranes)",
 "5 times faster","50 times faster"],
"B",
"CO2 diffuses approximately 20 times faster than O2 across the respiratory membrane, despite a smaller partial pressure gradient (~6 mmHg for CO2 vs ~60 mmHg for O2). This is because CO2 is approximately 20 times more soluble in the lipid membrane. This explains why diffusion impairment causes hypoxemia before hypercapnia."),

(75,
"The normal PO2 of mixed venous blood in the pulmonary artery is approximately:",
["100 mmHg","40 mmHg",
 "60 mmHg","70 mmHg"],
"B",
"Normal mixed venous (pulmonary artery) PO2 ≈ 40 mmHg, PCO2 ≈ 45 mmHg, O2 saturation ≈ 75%. After passing through the pulmonary capillaries, PO2 rises to ~100 mmHg and PCO2 falls to ~40 mmHg. The difference between arterial and venous O2 content reflects tissue oxygen extraction."),

# ─── SECTION G: O2 and CO2 Transport, Hb-O2 Dissociation Curve,
#               CO, Bicarbonate, Exchange Ratio (Q76–87)
(76,
"The oxygen-hemoglobin dissociation curve is sigmoidal in shape because:",
["Hemoglobin has a single oxygen binding site","Cooperative binding: the binding of one O2 molecule to hemoglobin increases the affinity of the remaining subunits for O2 (positive cooperativity)",
 "O2 is poorly soluble in blood","Myoglobin has a sigmoidal curve"],
"B",
"The sigmoidal shape of the Hb-O2 dissociation curve reflects cooperative (allosteric) binding. When one O2 binds to a heme group, it induces a conformational change (R-state) that increases affinity of the other subunits for O2. This produces a steep central portion and flat upper and lower portions, ideal for loading at the lungs and unloading at tissues."),

(77,
"A rightward shift of the oxygen-hemoglobin dissociation curve is caused by which of the following?",
["Decreased temperature, decreased PCO2, alkalosis","Increased temperature, increased PCO2, acidosis (Bohr effect), and increased 2,3-DPG",
 "Carbon monoxide poisoning","Methemoglobinemia"],
"B",
"The Bohr effect: increased CO2 and H+ (decreased pH), increased temperature, and increased 2,3-DPG all shift the Hb-O2 curve to the RIGHT (lower O2 affinity), facilitating O2 unloading at tissues. These conditions prevail in metabolically active tissues. The opposite conditions (alkalosis, hypothermia, low 2,3-DPG) shift the curve LEFT."),

(78,
"Carbon monoxide (CO) causes hypoxia by which mechanism?",
["Blocking cytochrome oxidase in mitochondria only","Binding hemoglobin with ~250 times higher affinity than O2, forming carboxyhemoglobin (COHb), which cannot carry O2, AND shifting the Hb-O2 curve leftward (Haldane effect)",
 "Causing bronchoconstriction","Reducing respiratory rate"],
"B",
"CO binds hemoglobin at the same site as O2 with ~250× greater affinity, forming carboxyhemoglobin (COHb). This reduces O2-carrying capacity. Additionally, CO causes a leftward shift of the Hb-O2 dissociation curve for the remaining heme groups, impairing O2 unloading at tissues (Haldane effect). Standard PO2 is normal but O2 content is critically low."),

(79,
"The P50 of hemoglobin refers to:",
["The PO2 at which hemoglobin is 100% saturated","The partial pressure of O2 at which hemoglobin is 50% saturated – normally about 26–27 mmHg",
 "The PCO2 at 50% CO2 saturation","The pH at 50% O2 binding"],
"B",
"P50 is the PO2 at which hemoglobin is 50% saturated. Normal P50 ≈ 26–27 mmHg. An increased P50 (rightward shift) means lower O2 affinity and better O2 delivery to tissues. A decreased P50 (leftward shift) means higher O2 affinity and impaired tissue O2 unloading."),

(80,
"The Haldane effect refers to:",
["The effect of pH on CO2 binding to Hb","Deoxygenation of hemoglobin greatly increases its ability to carry CO2 (as carbaminohemoglobin and by enhancing the buffering of H+ from CO2 hydration)",
 "The effect of CO2 on O2 binding (Bohr effect)","The effect of 2,3-DPG on the Hb-O2 curve"],
"B",
"The Haldane effect: deoxyhemoglobin (in tissues) binds CO2 as carbaminohemoglobin and also buffers more H+ (because deoxyHb is a better base/buffer). Oxyhemoglobin (in lungs) releases CO2 and H+, promoting CO2 elimination. The Haldane effect is approximately twice as important as the Bohr effect in CO2 transport."),

(81,
"Approximately what percentage of CO2 is transported in blood as bicarbonate ions?",
["10%","70% (as HCO3−); ~20–23% as carbaminohemoglobin; ~7% dissolved",
 "50%","90%"],
"B",
"CO2 is transported as: ~70% as bicarbonate ions (HCO3−, via CO2 + H2O → H2CO3 → H+ + HCO3−, catalyzed by carbonic anhydrase in RBCs); ~20–23% as carbaminohemoglobin (bound to Hb amino groups); ~7% dissolved in plasma. Bicarbonate is by far the dominant form."),

(82,
"The chloride shift (Hamburger shift) occurs because:",
["Chloride is co-transported with sodium","When bicarbonate is formed in RBCs and moves into plasma, Cl− moves from plasma into RBCs to maintain electrical neutrality",
 "Chloride activates carbonic anhydrase","Chloride replaces oxygen on hemoglobin"],
"B",
"As CO2 enters RBCs in tissues, carbonic anhydrase converts it to H2CO3 → H+ + HCO3−. HCO3− exits the RBC via the band 3 (AE1) exchanger and Cl− enters to maintain electrical neutrality. In the lungs, the reverse occurs. This chloride shift is essential for efficient CO2 transport."),

(83,
"The respiratory exchange ratio (R) during steady-state exercise on a mixed diet is approximately:",
["0.7 (fat oxidation only)","0.8–1.0 (mixed substrate oxidation; rises toward 1.0 with high-carbohydrate utilization and above 1.0 during anaerobic exercise",
 "1.5","0.5"],
"B",
"The respiratory exchange ratio (R = VCO2/VO2) reflects the substrate being oxidized. For fat: R = 0.70; for carbohydrate: R = 1.0; for protein: R ≈ 0.82. During heavy exercise, R can exceed 1.0 because lactic acid formation drives additional CO2 release via bicarbonate buffering. Mixed diet resting value ≈ 0.8."),

(84,
"2,3-Diphosphoglycerate (2,3-DPG) causes a rightward shift of the Hb-O2 curve by:",
["Increasing O2 affinity of hemoglobin","Binding to deoxygenated hemoglobin (beta chains) and stabilizing the T (tense, low-affinity) state, reducing O2 affinity",
 "Activating carbonic anhydrase","Competing with CO at heme sites"],
"B",
"2,3-DPG is produced in RBCs via the Rapoport-Luebering pathway. It binds to the beta chains of deoxyhemoglobin, stabilizing the T-state (low O2 affinity) and shifting the curve rightward. 2,3-DPG increases with chronic hypoxia (altitude, anemia, COPD), improving O2 unloading to tissues."),

(85,
"A patient with severe COPD has an arterial PO2 of 55 mmHg and PCO2 of 55 mmHg. The chronic hypercapnia is tolerated because:",
["CO2 has no effect on pH with time","Renal compensation increases bicarbonate retention, returning pH toward normal (metabolic alkalosis partially compensating respiratory acidosis)",
 "The respiratory center stops responding to CO2","Hypercapnia improves O2 unloading"],
"B",
"In chronic hypercapnia (type II respiratory failure), the kidneys compensate by retaining bicarbonate, raising plasma HCO3− to restore pH toward normal. This is chronic respiratory acidosis with metabolic compensation. The Hb-O2 curve is shifted rightward (Bohr effect), improving O2 delivery to tissues despite low PaO2."),

(86,
"Hemoglobin acts as a tissue oxygen 'buffer' because:",
["It releases all its O2 at the same PO2","The sigmoidal shape of the Hb-O2 curve means that large amounts of O2 are released for relatively small falls in tissue PO2 (in the steep part of the curve: 40–60 mmHg)",
 "It stores O2 indefinitely","It only releases O2 in the lungs"],
"B",
"The steep portion of the Hb-O2 curve (PO2 40–70 mmHg) acts as a buffer: small changes in tissue PO2 release large amounts of O2 from hemoglobin. At PO2 = 40 mmHg (tissues), Hb saturation is ~75%; if tissue PO2 falls to 20 mmHg, Hb falls to ~35%, releasing substantial additional O2 without a catastrophic drop in tissue PO2."),

(87,
"Fetal hemoglobin (HbF) has which property compared to adult hemoglobin (HbA)?",
["Rightward shift of Hb-O2 curve; lower O2 affinity","Leftward shift of Hb-O2 curve; higher O2 affinity – facilitating O2 transfer from maternal (HbA) to fetal blood across the placenta",
 "Same O2 affinity as HbA","Binds 2,3-DPG more strongly than HbA"],
"B",
"HbF has gamma chains instead of beta chains. It binds 2,3-DPG less strongly than HbA, resulting in a higher O2 affinity (leftward shift, lower P50 ≈ 18–20 mmHg vs 26–27 mmHg for HbA). This allows HbF to extract O2 from maternal HbA across the placenta despite the relatively low PO2 of umbilical venous blood."),

# ─── SECTION H: Regulation of Respiration – Respiratory Centre, Chemical Control,
#               Exercise, Cheyne-Stokes, Sleep Apnea (Q88–100)
(88,
"The respiratory center is located in which part of the brain, and it generates the basic rhythm of breathing?",
["Cerebral cortex and hypothalamus","The medulla oblongata (dorsal and ventral respiratory groups) and the pons (pneumotaxic and apneustic centers)",
 "Midbrain and cerebellum","Spinal cord only"],
"B",
"The respiratory center consists of: (1) Dorsal respiratory group (DRG) in the nucleus tractus solitarius – primarily inspiratory; (2) Ventral respiratory group (VRG) including the pre-Botzinger complex – generates the basic respiratory rhythm; (3) Pneumotaxic center (nucleus parabrachialis) – limits inspiration duration; (4) Apneustic center – prolongs inspiration."),

(89,
"The inspiratory 'ramp' signal from the respiratory center means:",
["Inspiration is a sudden all-or-none event","Action potentials to inspiratory muscles (diaphragm, external intercostals) increase gradually ('ramp up') over ~2 seconds during normal inspiration, then cut off abruptly",
 "Inspiration begins suddenly and ends gradually","Expiration is active"],
"B",
"During normal inspiration, the DRG fires in a ramp pattern: signals to inspiratory muscles increase progressively over ~2 seconds, causing a smooth, gradual increase in lung volume rather than a sudden gasp. The ramp is terminated abruptly by signals from the pneumotaxic center, and expiration follows passively."),

(90,
"Central chemoreceptors, which are the most important chemical stimulus for normal breathing, respond primarily to:",
["Arterial PO2","Changes in PCO2/H+ in the cerebrospinal fluid (CSF), specifically H+ concentration (not CO2 directly)",
 "Decreased arterial pH only","Arterial K+ concentration"],
"B",
"Central chemoreceptors are located on the ventral surface of the medulla. They respond to H+ in the CSF. CO2 freely crosses the blood-brain barrier and is converted to H+ in the CSF (CO2 + H2O → H2CO3 → H+ + HCO3−). Since HCO3− crosses the BBB slowly, CO2 changes rapidly alter CSF H+ and stimulate ventilation."),

(91,
"The peripheral chemoreceptors (carotid and aortic bodies) are primarily stimulated by:",
["Increased arterial PCO2 alone","Decreased arterial PO2 (below ~60 mmHg), increased PCO2, and decreased pH",
 "Increased arterial glucose","Decreased arterial pressure alone"],
"B",
"Peripheral chemoreceptors (carotid bodies more important; aortic bodies contribute) respond to all three: low PO2, high PCO2, and low pH. The response to low PO2 is the unique contribution of peripheral receptors (central receptors do not respond to hypoxia directly). Their response to hypoxia is critically important at altitude and in patients with chronic hypercapnia."),

(92,
"In a patient with severe COPD and chronic CO2 retention, the primary ventilatory drive becomes:",
["High PCO2 (CO2 drive dominates)","Hypoxic drive via peripheral chemoreceptors (because central receptors become tolerant to chronically elevated CO2/H+)",
 "Metabolic acidosis","Increased respiratory rate reflex"],
"B",
"In chronic hypercapnia, the CSF bicarbonate rises to buffer H+, making the central chemoreceptors less sensitive to the elevated PCO2. The patient's ventilatory drive shifts to the hypoxic drive via peripheral chemoreceptors. This is the physiological basis of the caution about giving high-flow O2 to COPD patients with CO2 retention, as removing the hypoxic drive can cause respiratory depression."),

(93,
"During moderate aerobic exercise, ventilation increases proportionally to CO2 production. The primary stimulus is:",
["Arterial PCO2 (which rises during exercise)","Neural feedforward signals from the motor cortex and proprioceptors from exercising muscles, combined with small increases in CO2 and H+; arterial PO2 and PCO2 remain near normal at moderate exercise",
 "Arterial PO2 (which falls during exercise)","Increased body temperature only"],
"B",
"During moderate exercise, ventilation matches CO2 production so precisely that arterial PCO2 barely changes. The major stimuli are: (1) neural – motor cortex signals ('feed-forward'), proprioceptors from exercising joints/muscles; (2) humoral – small rises in CO2, H+, K+, and temperature. Arterial PO2 does NOT fall significantly during moderate exercise in healthy individuals."),

(94,
"Cheyne-Stokes breathing is characterized by:",
["Rapid deep breathing at a constant rate","Cyclical waxing and waning of tidal volume with periodic apneas, caused by oscillation in the respiratory feedback loop",
 "Sustained apnea","Shallow breathing at a fixed rate"],
"B",
"Cheyne-Stokes breathing: ventilation gradually increases (hyperpnea) then decreases to an apnea, then cycles again. It is caused by instability in the chemoreflex loop: during hyperpnea, CO2 falls; during apnea, CO2 rises until it triggers the next breath. Common in severe heart failure (prolonged circulation time), strokes, and at high altitude."),

(95,
"The prolonged circulation time in severe heart failure contributes to Cheyne-Stokes breathing because:",
["The heart rate is too slow","Blood takes longer to travel from lungs to chemoreceptors, so the feedback response to CO2/O2 changes is delayed, causing overshoot oscillations",
 "Cardiac output is too high","There is metabolic alkalosis"],
"B",
"In heart failure, cardiac output is low, prolonging the transit time from lungs to carotid body chemoreceptors. The delayed feedback means the respiratory center over-corrects (continues hyperventilating after CO2 has already fallen), causing overshoot CO2 reduction, apnea, then CO2 rises again – producing the typical waxing-waning cycle."),

(96,
"Obstructive sleep apnea (OSA) is caused by:",
["Failure of the respiratory center to send signals during sleep","Repetitive collapse of the upper airway (pharynx) during sleep, causing cessation of airflow despite continued respiratory effort",
 "Central failure to initiate breathing","Low altitude hypoxia"],
"B",
"OSA is caused by collapse of the pharyngeal soft tissue during sleep when muscle tone decreases. There is continued respiratory effort (chest and abdominal movement) but no airflow. Each apnea causes hypoxia and hypercapnia until the patient arouses briefly and restores airway patency. Risk factors: obesity, large neck, retrognathia, alcohol."),

(97,
"Central sleep apnea differs from obstructive sleep apnea in that:",
["Central apnea has more snoring","In central sleep apnea, there is a failure of the respiratory center to send signals, resulting in cessation of BOTH airflow AND respiratory effort",
 "Central apnea responds better to CPAP","They are the same condition"],
"B",
"Central sleep apnea: the respiratory center fails to generate signals during sleep (no respiratory effort detected on chest/abdominal belts). Often associated with heart failure, stroke, or opioid use. OSA: respiratory effort continues but airway is obstructed. CPAP (continuous positive airway pressure) treats OSA; central sleep apnea may require adaptive servo-ventilation."),

(98,
"The Hering-Breuer inflation reflex prevents over-inflation of the lungs by:",
["Stimulating inspiratory neurons","Stretch receptors in the airways/lungs send signals via the vagus nerve to inhibit the inspiratory ramp and terminate inspiration when lungs are sufficiently inflated",
 "Reducing surfactant production","Stimulating the apneustic center"],
"B",
"Pulmonary stretch receptors (slowly adapting) in the bronchi and bronchioles are activated by lung inflation. They send signals via the vagus nerve to the pneumotaxic/apneustic centers, inhibiting the DRG inspiratory ramp and triggering the expiratory phase. This reflex prevents overdistension. At normal tidal volumes in adults, it plays a minor role but is important in neonates."),

(99,
"At high altitude (e.g., 4,000 m), a mountaineer develops hyperventilation. This is driven by:",
["Increased atmospheric PCO2","Decreased arterial PO2 stimulating peripheral chemoreceptors (carotid bodies), which increases ventilation, lowers PCO2, and causes respiratory alkalosis",
 "Decreased temperature","Increased cardiac output"],
"B",
"At altitude, reduced atmospheric PO2 lowers alveolar and arterial PO2, stimulating carotid body peripheral chemoreceptors. This increases ventilation, which lowers PCO2 and raises arterial pH (respiratory alkalosis). Over days, renal compensation (bicarbonate excretion) normalizes pH, and 2,3-DPG rises to improve O2 unloading – acclimatization."),

(100,
"A 65-year-old man with congestive heart failure, chronic renal failure, and COPD develops altered breathing. Which of the following would be MOST likely to precipitate Cheyne-Stokes breathing?",
["Normal cardiac output with good exercise tolerance","Severely reduced cardiac output causing prolonged circulation time, combined with hypersensitive chemoreceptors and fluctuating CO2/O2 levels during sleep",
 "Obstructive upper airway anatomy","High tidal volume ventilation"],
"B",
"Cheyne-Stokes breathing in this patient is driven by: (1) severely low cardiac output → prolonged circulation time → delayed feedback; (2) hypersensitive chemoreceptors (from chronic hypoxia/hypercapnia); (3) low arterial PCO2 threshold (close to apnea threshold). Together these create unstable oscillatory breathing, especially during sleep when voluntary override is lost."),
]

# ── section metadata ──────────────────────────────────────────────────────────
SECTIONS = [
    ("A","Nervous Regulation | Autonomic NS | Sympathetic Vasoconstrictor | Rapid Pressure Control","1–13"),
    ("B","Kidneys & Long-Term Pressure Control | RAAS | Hypertension","14–26"),
    ("C","Muscle Blood Flow & Cardiac Output in Exercise | Coronary Circulation | Cardiac Failure | Shock","27–39"),
    ("D","Pulmonary Ventilation | Pleural Pressure | Compliance | Surfactant | Volumes & Capacities | Dead Space","40–52"),
    ("E","Pulmonary Circulation | Fluid Exchange | Pulmonary Edema | Pleural Fluid","53–63"),
    ("F","Gas Exchange | Partial Pressures | Diffusion | V/Q Ratio | Physiological Shunt & Dead Space","64–75"),
    ("G","O2 & CO2 Transport | Hb-O2 Dissociation Curve | CO Poisoning | Bicarbonate | Exchange Ratio","76–87"),
    ("H","Regulation of Respiration | Chemical Control | Exercise | Cheyne-Stokes | Sleep Apnea","88–100"),
]

sec_start = {"A":1,"B":14,"C":27,"D":40,"E":53,"F":64,"G":76,"H":88}
boundary_to_sec = {v:k for k,v in sec_start.items()}
sec_meta = {ltr:(title,rng) for ltr,title,rng in SECTIONS}

# ── build PDF ──────────────────────────────────────────────────────────────────
def build():
    doc = SimpleDocTemplate(
        OUTPUT, pagesize=A4,
        leftMargin=2*cm, rightMargin=2*cm,
        topMargin=4.0*cm, bottomMargin=2.2*cm,
        title="MBBS Final – Guyton & Hall 100 MCQs",
        author="Orris Medical AI",
        subject="Guyton and Hall Medical Physiology 13th Edition"
    )
    story = [Spacer(1,0.4*cm)]

    # instructions box
    instr = ("<b>INSTRUCTIONS:</b>  Each question has ONE best answer. "
             "Read all options carefully before selecting. "
             "Clinical vignettes require application of physiological principles. "
             "Answers with explanations follow each question for self-assessment.")
    it = Table([[Paragraph(instr, INSTR_S)]], colWidths=[17*cm])
    it.setStyle(TableStyle([
        ("BACKGROUND",(0,0),(-1,-1),LITE),
        ("LINEALL",(0,0),(-1,-1),.5,MID),
        ("TOPPADDING",(0,0),(-1,-1),8),("BOTTOMPADDING",(0,0),(-1,-1),8),
        ("LEFTPADDING",(0,0),(-1,-1),10),("RIGHTPADDING",(0,0),(-1,-1),10),
    ]))
    story.append(it)
    story.append(Spacer(1,0.4*cm))

    for num, stem, opts, ans, expl in questions:
        if num in boundary_to_sec:
            ltr = boundary_to_sec[num]
            title, rng = sec_meta[ltr]
            story.append(sec_block(ltr, title, rng))
            story.append(Spacer(1,0.2*cm))
        story.append(qblock(num, stem, opts, ans, expl))

    doc.build(story, onFirstPage=first_page, onLaterPages=later_pages)
    print(f"DONE: {OUTPUT}")

if __name__ == "__main__":
    build()

cd /home/daytona/workspace/guyton-mcq && python3 build_pdf.py 2>&1

ls -lh /home/daytona/workspace/guyton-mcq/Guyton_Hall_100_MCQs.pdf