mkdir -p /home/daytona/workspace/physiology-exam && ls /home/daytona/workspace/p…

~/physiology-exam/gen_pdf.py

from reportlab.lib.pagesizes import A4
from reportlab.lib import colors
from reportlab.lib.styles import getSampleStyleSheet, ParagraphStyle
from reportlab.lib.units import cm, mm
from reportlab.platypus import (
    SimpleDocTemplate, Paragraph, Spacer, Table, TableStyle,
    HRFlowable, PageBreak, KeepTogether
)
from reportlab.platypus import ListItem, ListFlowable
from reportlab.lib.enums import TA_CENTER, TA_LEFT, TA_JUSTIFY
from reportlab.graphics.shapes import Drawing, Rect, String, Line, Arrow, Polygon, Circle
from reportlab.graphics.charts.barcharts import VerticalBarChart
from reportlab.graphics import renderPDF
from reportlab.platypus import Flowable
import reportlab.lib.colors as rcolors

# ── Colours ──────────────────────────────────────────────────────────────────
DARK_BLUE   = colors.HexColor("#1a237e")
MID_BLUE    = colors.HexColor("#1565c0")
LIGHT_BLUE  = colors.HexColor("#e3f2fd")
ACCENT      = colors.HexColor("#0288d1")
GREEN       = colors.HexColor("#2e7d32")
LIGHT_GREEN = colors.HexColor("#e8f5e9")
ORANGE      = colors.HexColor("#e65100")
LIGHT_ORG   = colors.HexColor("#fff3e0")
PURPLE      = colors.HexColor("#6a1b9a")
LIGHT_PURP  = colors.HexColor("#f3e5f5")
RED         = colors.HexColor("#c62828")
LIGHT_RED   = colors.HexColor("#ffebee")
TEAL        = colors.HexColor("#00695c")
LIGHT_TEAL  = colors.HexColor("#e0f2f1")
GREY_BG     = colors.HexColor("#f5f5f5")
WHITE       = colors.white
BLACK       = colors.black

# ── Document setup ────────────────────────────────────────────────────────────
doc = SimpleDocTemplate(
    "/home/daytona/workspace/physiology-exam/Physiology_Prelims_Answers.pdf",
    pagesize=A4,
    rightMargin=1.8*cm, leftMargin=1.8*cm,
    topMargin=2*cm, bottomMargin=2*cm
)
W, H = A4

styles = getSampleStyleSheet()

def S(name, **kw):
    """Quick style factory"""
    base = styles.get(name, styles["Normal"])
    return ParagraphStyle(name+"_custom", parent=base, **kw)

cover_title   = S("Title",   fontSize=26, textColor=WHITE, alignment=TA_CENTER, spaceAfter=6, leading=32)
cover_sub     = S("Normal",  fontSize=14, textColor=LIGHT_BLUE, alignment=TA_CENTER, spaceAfter=4)
cover_note    = S("Normal",  fontSize=11, textColor=colors.HexColor("#bbdefb"), alignment=TA_CENTER)

ch_title      = S("Heading1", fontSize=18, textColor=WHITE, alignment=TA_CENTER,
                   spaceBefore=0, spaceAfter=0, leading=22,
                   fontName="Helvetica-Bold")
q_title       = S("Heading2", fontSize=13, textColor=DARK_BLUE,
                   spaceBefore=10, spaceAfter=4, leading=16,
                   fontName="Helvetica-Bold")
sub_head      = S("Heading3", fontSize=11, textColor=MID_BLUE,
                   spaceBefore=6, spaceAfter=3, leading=14,
                   fontName="Helvetica-Bold")
body          = S("Normal",   fontSize=10, textColor=BLACK,
                   spaceAfter=3, leading=14, alignment=TA_JUSTIFY)
bullet_style  = S("Normal",   fontSize=10, textColor=BLACK,
                   spaceAfter=2, leading=13, leftIndent=14,
                   bulletIndent=4)
ref_style     = S("Normal",   fontSize=9, textColor=PURPLE,
                   spaceAfter=2, leading=12, fontName="Helvetica-Oblique")
key_style     = S("Normal",   fontSize=10, textColor=RED,
                   spaceAfter=2, leading=13, fontName="Helvetica-Bold")
note_style    = S("Normal",   fontSize=9.5, textColor=colors.HexColor("#4e342e"),
                   spaceAfter=3, leading=13, leftIndent=8)

def ref(text):
    return Paragraph(f"📚 Reference: {text}", ref_style)

def bullet(items, color=MID_BLUE):
    return ListFlowable(
        [ListItem(Paragraph(i, bullet_style), bulletColor=color, bulletFontSize=9)
         for i in items],
        bulletType='bullet', leftIndent=18, bulletOffsetY=-2
    )

def numbered(items):
    return ListFlowable(
        [ListItem(Paragraph(i, bullet_style), bulletColor=GREEN)
         for i in items],
        bulletType='1', leftIndent=20
    )

def key_point(text):
    return Paragraph(f"★ {text}", key_style)

def note(text):
    return Paragraph(f"Note: {text}", note_style)


# ── Chapter header helper ─────────────────────────────────────────────────────
def chapter_header(title, color=DARK_BLUE):
    data = [[Paragraph(title, ch_title)]]
    t = Table(data, colWidths=[W - 3.6*cm])
    t.setStyle(TableStyle([
        ("BACKGROUND", (0,0), (-1,-1), color),
        ("ROUNDEDCORNERS", [8]),
        ("TOPPADDING",    (0,0), (-1,-1), 10),
        ("BOTTOMPADDING", (0,0), (-1,-1), 10),
        ("LEFTPADDING",   (0,0), (-1,-1), 14),
        ("RIGHTPADDING",  (0,0), (-1,-1), 14),
    ]))
    return t

def section_box(title, bg=LIGHT_BLUE, tc=DARK_BLUE):
    p = ParagraphStyle("sb", fontSize=11.5, textColor=tc,
                       fontName="Helvetica-Bold", leading=14)
    data = [[Paragraph(title, p)]]
    t = Table(data, colWidths=[W - 3.6*cm])
    t.setStyle(TableStyle([
        ("BACKGROUND", (0,0), (-1,-1), bg),
        ("LEFTPADDING",   (0,0), (-1,-1), 10),
        ("RIGHTPADDING",  (0,0), (-1,-1), 10),
        ("TOPPADDING",    (0,0), (-1,-1), 6),
        ("BOTTOMPADDING", (0,0), (-1,-1), 6),
        ("LINEBELOW", (0,0), (-1,-1), 1.5, tc),
    ]))
    return t

def divider(color=ACCENT):
    return HRFlowable(width="100%", thickness=1, color=color, spaceAfter=4, spaceBefore=4)

def tbl(headers, rows, col_widths=None, hdr_bg=MID_BLUE):
    data = [[Paragraph(str(h), S("Normal", fontSize=9.5, textColor=WHITE,
                                 fontName="Helvetica-Bold")) for h in headers]]
    for row in rows:
        data.append([Paragraph(str(c), S("Normal", fontSize=9, textColor=BLACK)) for c in row])
    cw = col_widths or [(W - 3.6*cm) / len(headers)] * len(headers)
    t = Table(data, colWidths=cw, repeatRows=1)
    style = [
        ("BACKGROUND", (0,0), (-1,0), hdr_bg),
        ("GRID",       (0,0), (-1,-1), 0.5, colors.grey),
        ("TOPPADDING",    (0,0), (-1,-1), 5),
        ("BOTTOMPADDING", (0,0), (-1,-1), 5),
        ("LEFTPADDING",   (0,0), (-1,-1), 6),
        ("RIGHTPADDING",  (0,0), (-1,-1), 6),
        ("ROWBACKGROUNDS",(0,1), (-1,-1), [WHITE, GREY_BG]),
        ("VALIGN",     (0,0), (-1,-1), "TOP"),
    ]
    t.setStyle(TableStyle(style))
    return t


# ══════════════════════════════════════════════════════════════════════════════
# FLOWCHART helpers  (pure ReportLab Drawing)
# ══════════════════════════════════════════════════════════════════════════════
class FlowChart(Flowable):
    """Generic ASCII-style box-and-arrow vertical flowchart."""
    def __init__(self, steps, width=460, box_h=28, gap=18,
                 fill=LIGHT_BLUE, stroke=MID_BLUE, txt_color=DARK_BLUE):
        super().__init__()
        self.steps     = steps
        self.box_w     = width
        self.box_h     = box_h
        self.gap       = gap
        self.fill      = fill
        self.stroke    = stroke
        self.txt_color = txt_color
        n              = len(steps)
        self.width     = width
        self.height    = n * box_h + (n-1) * gap + 10

    def draw(self):
        c = self.canv
        y = self.height - 10
        for i, step in enumerate(self.steps):
            top = y
            bot = y - self.box_h
            c.setFillColor(self.fill)
            c.setStrokeColor(self.stroke)
            c.setLineWidth(1.2)
            c.roundRect(0, bot, self.box_w, self.box_h, 5, fill=1, stroke=1)
            c.setFillColor(self.txt_color)
            c.setFont("Helvetica-Bold", 9)
            c.drawCentredString(self.box_w/2, bot + self.box_h/2 - 4, step)
            # arrow
            if i < len(self.steps) - 1:
                ax = self.box_w / 2
                c.setStrokeColor(self.stroke)
                c.setFillColor(self.stroke)
                c.setLineWidth(1.5)
                c.line(ax, bot, ax, bot - self.gap + 6)
                # arrowhead
                c.setLineWidth(0)
                c.triangle(ax-4, bot-self.gap+8, ax+4, bot-self.gap+8,
                           ax, bot-self.gap+2, fill=1)
            y = bot - self.gap


def simple_flowchart(steps, width=460, fill=LIGHT_BLUE, stroke=MID_BLUE):
    return FlowChart(steps, width=width, fill=fill, stroke=stroke)


# ══════════════════════════════════════════════════════════════════════════════
# BUILD STORY
# ══════════════════════════════════════════════════════════════════════════════
story = []

# ─── COVER PAGE ───────────────────────────────────────────────────────────────
cover_data = [[Paragraph("PHYSIOLOGY\nPRELIMS EXAM", cover_title)]]
cover_tbl = Table(cover_data, colWidths=[W - 3.6*cm])
cover_tbl.setStyle(TableStyle([
    ("BACKGROUND", (0,0), (-1,-1), DARK_BLUE),
    ("TOPPADDING",    (0,0), (-1,-1), 30),
    ("BOTTOMPADDING", (0,0), (-1,-1), 30),
]))
story.append(Spacer(1, 3*cm))
story.append(cover_tbl)
story.append(Spacer(1, 0.5*cm))

sub_data = [[Paragraph("1st Year MBBS — Complete Answer Key", cover_sub)]]
sub_tbl = Table(sub_data, colWidths=[W - 3.6*cm])
sub_tbl.setStyle(TableStyle([
    ("BACKGROUND", (0,0), (-1,-1), MID_BLUE),
    ("TOPPADDING",    (0,0), (-1,-1), 12),
    ("BOTTOMPADDING", (0,0), (-1,-1), 12),
]))
story.append(sub_tbl)
story.append(Spacer(1, 0.5*cm))

note_data = [[Paragraph(
    "Sections Covered: General · Blood · Muscle · Digestive\n"
    "Reference: Guyton & Hall (14e) · Ganong (26e) · Costanzo (7e)",
    cover_note)]]
note_tbl = Table(note_data, colWidths=[W - 3.6*cm])
note_tbl.setStyle(TableStyle([
    ("BACKGROUND", (0,0), (-1,-1), ACCENT),
    ("TOPPADDING",    (0,0), (-1,-1), 10),
    ("BOTTOMPADDING", (0,0), (-1,-1), 10),
]))
story.append(note_tbl)
story.append(PageBreak())


# ══════════════════════════════════════════════════════════════════════════════
# SECTION 1 — GENERAL
# ══════════════════════════════════════════════════════════════════════════════
story.append(chapter_header("SECTION 1: GENERAL PHYSIOLOGY", DARK_BLUE))
story.append(Spacer(1, 0.3*cm))

# ─── Q1: Mitochondria ─────────────────────────────────────────────────────────
story.append(section_box("Q1. Mitochondria (Cell Organelle) [R]", LIGHT_BLUE, DARK_BLUE))
story.append(Spacer(1,0.15*cm))
story.append(Paragraph("A. Introduction", sub_head))
story.append(bullet([
    "Mitochondria = powerhouses of the cell",
    "Site of ATP synthesis via oxidative phosphorylation",
    "Contain their own DNA (mtDNA, 37 genes) — maternally inherited",
    "Self-replicating organelles",
]))
story.append(Paragraph("B. Structure", sub_head))
story.append(tbl(
    ["Component", "Description"],
    [
        ["Outer membrane", "Contains porins; regulates ion/metabolite flow"],
        ["Inner membrane", "Folded into cristae; contains oxidative enzymes & ETC"],
        ["Cristae", "Infoldings that increase surface area for reactions"],
        ["Matrix", "Contains dissolved enzymes, mtDNA, ribosomes"],
        ["Intermembrane space", "Between outer and inner membrane; proton reservoir"],
    ],
    col_widths=[6*cm, 10.5*cm]
))
story.append(Paragraph("C. Functions", sub_head))
story.append(numbered([
    "ATP synthesis (oxidative phosphorylation)",
    "Fatty acid beta-oxidation",
    "Kreb's cycle (TCA cycle) — in matrix",
    "Calcium homeostasis",
    "Apoptosis initiation (release of cytochrome c)",
    "Heat production (thermogenesis)",
    "Steroid hormone synthesis",
]))
story.append(ref("Guyton & Hall, 14e, Ch.2 — The Cell and Its Functions"))
story.append(divider())

# ─── Q2: Apoptosis ────────────────────────────────────────────────────────────
story.append(section_box("Q2. Apoptosis [S5]", LIGHT_GREEN, GREEN))
story.append(Spacer(1,0.15*cm))
story.append(Paragraph("A. Definition", sub_head))
story.append(body.clone("b2", parent=body))
story.append(Paragraph(
    "Apoptosis is programmed cell death — a genetically controlled, energy-dependent process "
    "of self-destruction that eliminates unwanted, damaged, or aged cells without inflammation.", body))
story.append(Paragraph("B. Pathways", sub_head))
story.append(tbl(
    ["Pathway", "Trigger", "Key Mediators"],
    [
        ["Intrinsic (Mitochondrial)", "DNA damage, oxidative stress, ischaemia",
         "Cytochrome c → Apoptosome → Caspase-9 → Caspase-3"],
        ["Extrinsic (Death Receptor)", "FasL, TNF-α binding to death receptors",
         "FADD → Caspase-8 → Caspase-3"],
    ],
    col_widths=[4.5*cm, 5.5*cm, 6.5*cm]
))
story.append(Paragraph("C. Morphological Features", sub_head))
story.append(bullet([
    "Cell shrinkage (pyknosis)",
    "Chromatin condensation",
    "Membrane blebbing",
    "Formation of apoptotic bodies",
    "Phagocytosis by macrophages — NO inflammation",
]))
story.append(Paragraph("D. Physiological Roles", sub_head))
story.append(bullet([
    "Embryogenesis (digit separation, neural tube formation)",
    "Hormone-induced involution (endometrium)",
    "Immune system regulation (deletion of auto-reactive T-cells)",
    "Elimination of DNA-damaged cells — prevents cancer",
]))
story.append(key_point("KEY: Apoptosis ≠ Necrosis — No inflammation, No cell lysis in apoptosis"))
story.append(tbl(
    ["Feature", "Apoptosis", "Necrosis"],
    [
        ["Trigger", "Physiological/mild injury", "Severe, irreversible injury"],
        ["Cell size", "Shrinks", "Swells"],
        ["DNA", "Ladder pattern (internucleosomal)", "Random fragmentation"],
        ["Membrane", "Intact → apoptotic bodies", "Ruptures"],
        ["Inflammation", "None", "Present"],
        ["Energy", "ATP-dependent", "ATP-independent"],
    ],
    col_widths=[4*cm, 5.5*cm, 7*cm]
))
story.append(ref("Guyton & Hall, 14e, Ch.3; Ganong 26e, Ch.1"))
story.append(divider())

# ─── Q3: Gap Junction ─────────────────────────────────────────────────────────
story.append(section_box("Q3. Gap Junctions [S2]", LIGHT_PURP, PURPLE))
story.append(Spacer(1,0.15*cm))
story.append(bullet([
    "Gap junctions are intercellular channels formed by connexin proteins",
    "Two hemi-channels (connexons) from adjacent cells align to form a complete channel",
    "Pore diameter: ~1.5 nm — allows ions and small molecules (<1000 Da) to pass",
    "Allows direct electrical and chemical communication between cells",
]))
story.append(Paragraph("Functions:", sub_head))
story.append(bullet([
    "Electrical coupling — cardiac muscle & smooth muscle (functional syncytium)",
    "Metabolic coupling — sharing of nutrients and signalling molecules",
    "Coordinated contraction in cardiac and uterine muscle",
    "Embryonic development — pattern formation",
]))
story.append(ref("Guyton & Hall, 14e, Ch.2; Ganong 26e, Ch.2"))
story.append(divider())

# ─── Q4: Active & Passive Transport + Osmosis ─────────────────────────────────
story.append(section_box("Q4. Active & Passive Transport and Osmosis [S10]", LIGHT_TEAL, TEAL))
story.append(Spacer(1,0.15*cm))
story.append(tbl(
    ["Feature", "Passive Transport", "Active Transport"],
    [
        ["Energy required", "No", "Yes (ATP)"],
        ["Direction", "Down concentration gradient", "Against concentration gradient"],
        ["Carrier", "Not always needed", "Always needs carrier"],
        ["Types", "Diffusion, Facilitated diffusion, Osmosis", "Primary, Secondary (co-transport)"],
        ["Examples", "O₂, CO₂, glucose (via GLUT)", "Na⁺-K⁺ ATPase, Ca²⁺ pump"],
    ],
    col_widths=[4.5*cm, 5.5*cm, 6.5*cm]
))
story.append(Paragraph("A. Diffusion", sub_head))
story.append(bullet([
    "Movement of molecules from high → low concentration",
    "Rate governed by Fick's Law: J = -DA(dC/dx)",
    "Simple diffusion: lipid-soluble substances (O₂, CO₂, steroids)",
    "Facilitated diffusion: uses protein channels or carriers (glucose, amino acids)",
]))
story.append(Paragraph("B. Osmosis", sub_head))
story.append(bullet([
    "Movement of water across a semipermeable membrane from low → high solute concentration",
    "Osmotic pressure (π) = CRT (van't Hoff equation)",
    "Plasma osmolality: 285–295 mOsm/kg",
    "Isosmotic: same osmolarity | Hyperosmotic: higher osmolarity | Hyposmotic: lower",
]))
story.append(Paragraph("C. Primary Active Transport", sub_head))
story.append(bullet([
    "Na⁺-K⁺ ATPase: pumps 3 Na⁺ OUT, 2 K⁺ IN per ATP — maintains RMP",
    "H⁺-K⁺ ATPase: in parietal cells of stomach",
    "Ca²⁺ ATPase: in SR and plasma membrane",
]))
story.append(Paragraph("D. Secondary Active Transport", sub_head))
story.append(bullet([
    "Co-transport (symport): Na⁺-glucose cotransporter (SGLT) in intestine and kidney",
    "Counter-transport (antiport): Na⁺-H⁺ exchanger",
]))
story.append(ref("Costanzo Physiology, 7e, Ch.1; Guyton & Hall, 14e, Ch.4"))
story.append(divider())

# ─── Q5: Pinocytosis & Phagocytosis ──────────────────────────────────────────
story.append(section_box("Q5. Pinocytosis and Phagocytosis [S2]", LIGHT_ORG, ORANGE))
story.append(Spacer(1,0.15*cm))
story.append(tbl(
    ["Feature", "Pinocytosis", "Phagocytosis"],
    [
        ["Meaning", '"Cell drinking"', '"Cell eating"'],
        ["Material ingested", "Fluid + dissolved solutes", "Large solid particles (>0.5 μm)"],
        ["Cells involved", "Most cells", "Macrophages, neutrophils, monocytes"],
        ["Vesicle", "Pinosome (small)", "Phagosome (large)"],
        ["Examples", "Absorption of nutrients", "Bacteria, dead cells, debris"],
    ],
    col_widths=[4*cm, 5.5*cm, 7*cm]
))
story.append(ref("Guyton & Hall, 14e, Ch.2"))
story.append(divider())

# ─── Q6: MOA of Homeostatic System ───────────────────────────────────────────
story.append(section_box("Q6. Mechanism of Action of Homeostatic System [S10]", LIGHT_BLUE, DARK_BLUE))
story.append(Spacer(1,0.15*cm))
story.append(Paragraph(
    "Homeostasis is the maintenance of a stable internal environment despite external changes. "
    "It operates through feedback control systems.", body))
story.append(Paragraph("Components of a Control System:", sub_head))
story.append(simple_flowchart([
    "STIMULUS → Disturbs set point",
    "SENSOR / RECEPTOR detects change",
    "AFFERENT PATHWAY sends signal",
    "CONTROL CENTRE (Integrator) compares to set point",
    "EFFERENT PATHWAY sends corrective signal",
    "EFFECTOR makes correction",
    "RESPONSE → Restores set point (Feedback)",
], fill=LIGHT_BLUE, stroke=MID_BLUE))
story.append(Spacer(1,0.2*cm))
story.append(tbl(
    ["Feature", "Negative Feedback", "Positive Feedback"],
    [
        ["Direction", "Reverses the initial change", "Amplifies the initial change"],
        ["Common?", "Most common", "Uncommon"],
        ["Purpose", "Restores homeostasis", "Drives process to completion"],
        ["Examples", "Body temperature, blood glucose, blood pressure",
         "Oxytocin in labour, blood clotting, action potential depolarization"],
    ],
    col_widths=[4*cm, 5.5*cm, 7*cm]
))
story.append(key_point("Feed-forward control: Anticipatory responses before disruption occurs (e.g., insulin release before meal is complete)"))
story.append(ref("Guyton & Hall, 14e, Ch.1; Ganong 26e, Ch.1"))
story.append(PageBreak())


# ══════════════════════════════════════════════════════════════════════════════
# SECTION 2 — BLOOD
# ══════════════════════════════════════════════════════════════════════════════
story.append(chapter_header("SECTION 2: BLOOD", MID_BLUE))
story.append(Spacer(1, 0.3*cm))

# ─── Q7: Functions of Blood & Plasma Proteins ────────────────────────────────
story.append(section_box("Q7. Functions of Blood and Plasma Proteins [S5]", LIGHT_BLUE, DARK_BLUE))
story.append(Paragraph("A. Functions of Blood", sub_head))
story.append(numbered([
    "Transport: O₂, CO₂, nutrients, hormones, waste",
    "Regulation: temperature, pH, fluid balance",
    "Protection: WBCs, antibodies, clotting factors",
    "Homeostasis: acid-base balance, osmotic balance",
]))
story.append(Paragraph("B. Plasma Proteins", sub_head))
story.append(tbl(
    ["Protein", "% of Total", "Functions"],
    [
        ["Albumin", "54–60%", "Oncotic pressure, carrier protein, drug binding, buffer"],
        ["Globulin (α, β, γ)", "35–38%", "α: transport (ceruloplasmin, haptoglobin); β: iron transport (transferrin); γ: immunoglobulins (antibodies)"],
        ["Fibrinogen", "4–7%", "Coagulation — converted to fibrin by thrombin"],
        ["Prothrombin", "<1%", "Clotting (Factor II precursor)"],
    ],
    col_widths=[3.5*cm, 2.5*cm, 10.5*cm]
))
story.append(key_point("Normal plasma protein = 6–8 g/dL; Albumin = 3.5–5 g/dL"))
story.append(ref("Guyton & Hall, 14e, Ch.32"))
story.append(divider())

# ─── Q8: Biconcave Shape ─────────────────────────────────────────────────────
story.append(section_box("Q8. Advantages of Biconcave Shape of RBC [SQ]", LIGHT_GREEN, GREEN))
story.append(numbered([
    "Increased Surface-to-Volume ratio → maximises gas exchange",
    "Flexibility — can squeeze through capillaries (3 μm diameter) despite 8 μm size",
    "Shorter diffusion distance to haemoglobin",
    "No nucleus or mitochondria → more room for Hb → carries 280 million Hb molecules",
    "Uniform distribution of Hb across the cell",
    "MCV (mean cell volume) remains constant — reflects deformability",
]))
story.append(ref("Guyton & Hall, 14e, Ch.32"))
story.append(divider())

# ─── Q9: Fate of Hb ─────────────────────────────────────────────────────────
story.append(section_box("Q9. Fate of Haemoglobin [S5]", LIGHT_ORG, ORANGE))
story.append(simple_flowchart([
    "RBC lifespan = 120 days → Destroyed in spleen/liver by macrophages (RES)",
    "Hb released → split into Haem + Globin",
    "Globin → hydrolysed to amino acids → reutilised",
    "Haem → Fe³⁺ released + Protoporphyrin ring",
    "Fe³⁺ → stored as Ferritin/Haemosiderin OR transported by Transferrin to bone marrow",
    "Protoporphyrin → Biliverdin (green) → Bilirubin (yellow, unconjugated)",
    "Bilirubin → bound to albumin → liver → conjugated (glucuronide) → bile",
    "In gut → Urobilinogen → Stercobilin (faeces) + Urobilin (urine)",
], fill=LIGHT_ORG, stroke=ORANGE))
story.append(key_point("Normal serum bilirubin = 0.2–1.2 mg/dL; Jaundice appears >2 mg/dL"))
story.append(ref("Guyton & Hall, 14e, Ch.32"))
story.append(divider())

# ─── Q10: Erythropoiesis ─────────────────────────────────────────────────────
story.append(section_box("Q10. Stages and Factors of Erythropoiesis [S10]", LIGHT_TEAL, TEAL))
story.append(Paragraph("A. Stages of Erythropoiesis", sub_head))
story.append(simple_flowchart([
    "Pluripotent Stem Cell (Haemocytoblast)",
    "Committed Erythroid Progenitor (BFU-E → CFU-E)",
    "Proerythroblast (Pronormoblast) — basophilic; starts Hb synthesis",
    "Early Normoblast (Basophilic erythroblast) — active Hb synthesis",
    "Intermediate Normoblast (Polychromatic erythroblast)",
    "Late Normoblast (Orthochromatic) — nucleus ejected",
    "Reticulocyte — enters bloodstream; loses ribosomes in 1–2 days",
    "Mature Erythrocyte (RBC) — 7.2 μm biconcave disc",
], fill=LIGHT_TEAL, stroke=TEAL))
story.append(Paragraph("B. Factors Required for Erythropoiesis", sub_head))
story.append(tbl(
    ["Factor", "Role"],
    [
        ["Erythropoietin (EPO)", "Primary stimulus; produced by peritubular cells of kidney in response to hypoxia"],
        ["Iron (Fe²⁺)", "Essential for haem synthesis (Hb structure)"],
        ["Vitamin B12 (Cobalamin)", "DNA synthesis; requires intrinsic factor for absorption"],
        ["Folic Acid", "DNA synthesis (thymidine synthesis)"],
        ["Vitamin C", "Fe³⁺ → Fe²⁺ (enhances absorption)"],
        ["Vitamin B6 (Pyridoxine)", "Porphyrin/haem synthesis"],
        ["Copper", "Iron mobilisation (ceruloplasmin)"],
        ["Cobalt", "Stimulates EPO release"],
        ["Protein (Amino acids)", "Globin chain synthesis"],
    ],
    col_widths=[5*cm, 11.5*cm]
))
story.append(ref("Guyton & Hall, 14e, Ch.33; Ganong 26e, Ch.26"))
story.append(divider())

# ─── Q11: Anaemia Classification ─────────────────────────────────────────────
story.append(section_box("Q11. Classification of Anaemia [S3]", LIGHT_RED, RED))
story.append(tbl(
    ["Classification", "Types", "Examples"],
    [
        ["By MCV (Morphological)",
         "Microcytic (MCV<80)\nNormocytic (MCV 80–100)\nMacrocytic (MCV>100)",
         "IDA, Thalassaemia\nHaemolytic, aplastic, acute blood loss\nVit B12/Folate deficiency"],
        ["By Reticulocyte Count",
         "Hyperproliferative (retics ↑)\nHypoproliferative (retics ↓)",
         "Haemolysis, blood loss\nBone marrow failure, nutritional"],
        ["By Aetiology",
         "Decreased production\nIncreased destruction\nBlood loss",
         "Aplastic, nutritional\nHaemolytic\nAcute/chronic"],
    ],
    col_widths=[4*cm, 5.5*cm, 7*cm]
))
story.append(ref("Guyton & Hall, 14e, Ch.33"))
story.append(divider())

# ─── Q12: Iron-Def / Megaloblastic / Haemorrhagic Anaemia ────────────────────
story.append(section_box("Q12. Iron Deficiency, Megaloblastic, and Haemorrhagic Anaemia [S10]", LIGHT_RED, RED))
story.append(tbl(
    ["Feature", "Iron Deficiency Anaemia", "Megaloblastic Anaemia", "Haemorrhagic Anaemia"],
    [
        ["Cause", "Low iron intake, chronic blood loss, malabsorption",
         "Vit B12 deficiency (pernicious) or Folate deficiency",
         "Acute/chronic blood loss"],
        ["MCV", "Low (microcytic)", "High (macrocytic)", "Normal initially"],
        ["Hb", "Low", "Low", "Low"],
        ["RBC morphology", "Hypochromic, microcytic, pencil cells",
         "Macro-ovalocytes, hypersegmented neutrophils",
         "Normocytic normochromic"],
        ["Serum iron", "↓", "Normal", "↓ (chronic)"],
        ["Ferritin", "↓", "Normal", "↓ (chronic)"],
        ["TIBC", "↑", "Normal", "↑ (chronic)"],
        ["Special findings", "Koilonychia, angular stomatitis, glossitis",
         "Subacute combined degeneration of spinal cord (B12)",
         "↑ reticulocytes (compensation)"],
        ["Treatment", "Oral ferrous sulphate", "Vit B12 IM / Folic acid",
         "Stop bleeding, iron, transfusion if severe"],
    ],
    col_widths=[3.5*cm, 4.5*cm, 5*cm, 4.5*cm]
))
story.append(ref("Guyton & Hall, 14e, Ch.33"))
story.append(divider())

# ─── Q13: Cell-Mediated & Humoral Immunity ────────────────────────────────────
story.append(section_box("Q13. Cell-Mediated and Humoral Immunity [S10]", LIGHT_BLUE, DARK_BLUE))
story.append(tbl(
    ["Feature", "Humoral Immunity", "Cell-Mediated Immunity"],
    [
        ["Cells involved", "B lymphocytes → Plasma cells", "T lymphocytes (CD4⁺ helper, CD8⁺ cytotoxic)"],
        ["Mediator", "Antibodies (IgG, IgM, IgA, IgE, IgD)", "Lymphokines, cytokines (IL-2, IFN-γ)"],
        ["Target", "Extracellular pathogens, toxins", "Intracellular pathogens, virus-infected cells, tumour cells, transplants"],
        ["Memory", "Long-lived plasma cells + memory B cells", "Memory T cells"],
        ["Passive transfer", "By serum (IgG)", "By T lymphocytes"],
    ],
    col_widths=[4*cm, 5.5*cm, 7*cm]
))
story.append(Paragraph("Classes of Immunoglobulins:", sub_head))
story.append(tbl(
    ["Ig Class", "Location / Role"],
    [
        ["IgG", "Most abundant; crosses placenta; secondary response"],
        ["IgM", "Largest; first in primary response; pentamer"],
        ["IgA", "Secretory (saliva, tears, breast milk); dimer"],
        ["IgE", "Allergy / anaphylaxis; parasites"],
        ["IgD", "B-cell surface receptor; minor role"],
    ],
    col_widths=[3*cm, 13.5*cm]
))
story.append(ref("Guyton & Hall, 14e, Ch.35; Ganong 26e, Ch.3"))
story.append(divider())

# ─── Q14: Platelets ──────────────────────────────────────────────────────────
story.append(section_box("Q14. Functions of Platelets [S3]", LIGHT_GREEN, GREEN))
story.append(bullet([
    "Normal count: 1.5–4 × 10⁵/μL; Lifespan: 8–10 days",
    "Formed from megakaryocytes in bone marrow",
]))
story.append(tbl(
    ["Function", "Details"],
    [
        ["Vascular repair", "Adhere to damaged endothelium via vWF → temporary platelet plug"],
        ["Vasoconstriction", "Release thromboxane A₂ (TXA₂) → powerful vasoconstrictor"],
        ["Coagulation support", "Provide phospholipid surface (PF3) for coagulation cascade"],
        ["Clot retraction", "Contain actin & myosin → thrombostenin → clot retraction"],
        ["Wound healing", "Release PDGF → stimulates fibroblast proliferation"],
        ["Fibrinolysis", "Release plasminogen activator"],
    ],
    col_widths=[4.5*cm, 12*cm]
))
story.append(ref("Guyton & Hall, 14e, Ch.37"))
story.append(divider())

# ─── Q15: Haemostasis Chart ──────────────────────────────────────────────────
story.append(section_box("Q15. Haemostasis — Chart [S3]", LIGHT_TEAL, TEAL))
story.append(simple_flowchart([
    "VESSEL INJURY",
    "1. VASCULAR SPASM — immediate reflex vasoconstriction",
    "2. PRIMARY HAEMOSTASIS — Platelet adhesion (vWF), activation, aggregation → Platelet plug",
    "3. SECONDARY HAEMOSTASIS — Coagulation cascade → Fibrin clot",
    "4. FIBRINOLYSIS — Plasmin dissolves clot; vessel repairs",
], fill=LIGHT_TEAL, stroke=TEAL))
story.append(ref("Guyton & Hall, 14e, Ch.37"))
story.append(divider())

# ─── Q16: Blood Coagulation (Stages) ─────────────────────────────────────────
story.append(section_box("Q16. Stages of Blood Coagulation [S5]", LIGHT_BLUE, DARK_BLUE))
story.append(tbl(
    ["Pathway", "Factors Involved", "Activated by"],
    [
        ["Extrinsic Pathway", "Tissue Factor (III) + Factor VIIa",
         "Vessel wall damage → Tissue Factor released"],
        ["Intrinsic Pathway",
         "XII → XI → IX → VIII (tenase complex)",
         "Contact of blood with collagen / foreign surface"],
        ["Common Pathway",
         "X → Xa + Va (prothrombinase) → Prothrombin (II) → Thrombin (IIa) → Fibrinogen → Fibrin → Factor XIIIa stabilises fibrin",
         "Both pathways converge at Factor X"],
    ],
    col_widths=[4*cm, 6*cm, 6.5*cm]
))
story.append(key_point("Mnemonic — Intrinsic: 12, 11, 9, 8 (1-2-9-8) | Extrinsic: 7 | Common: 10, 5, 2, 1"))
story.append(tbl(
    ["Lab Test", "Tests"],
    [
        ["PT (Prothrombin Time)", "Extrinsic + Common pathway (Normal: 11–13 sec)"],
        ["aPTT", "Intrinsic + Common pathway (Normal: 25–35 sec)"],
        ["Bleeding Time", "Primary haemostasis / platelet function (Normal: 2–7 min)"],
        ["Clotting Time", "Overall coagulation (Normal: 5–10 min)"],
    ],
    col_widths=[5.5*cm, 11*cm]
))
story.append(ref("Guyton & Hall, 14e, Ch.37; Ganong 26e, Ch.31"))
story.append(divider())

# ─── Q17: Anticoagulation + Fibrinolysis ─────────────────────────────────────
story.append(section_box("Q17. Anticoagulation Mechanism, Fibrinolysis, and Anticoagulants [S5]", LIGHT_PURP, PURPLE))
story.append(Paragraph("A. Natural Anticoagulants", sub_head))
story.append(tbl(
    ["Anticoagulant", "Mechanism"],
    [
        ["Antithrombin III (ATIII)", "Inactivates thrombin, Xa, IXa, XIa; enhanced 1000× by heparin"],
        ["Protein C + Protein S", "Vitamin K-dependent; inactivates Factors Va and VIIIa"],
        ["Tissue Factor Pathway Inhibitor (TFPI)", "Inhibits Tissue Factor-VIIa complex"],
        ["Prostacyclin (PGI₂)", "Released by intact endothelium; inhibits platelet aggregation"],
        ["Thrombomodulin", "Endothelial receptor; thrombin-thrombomodulin complex activates Protein C"],
    ],
    col_widths=[5*cm, 11.5*cm]
))
story.append(Paragraph("B. Fibrinolysis", sub_head))
story.append(simple_flowchart([
    "Thrombin + vessel injury → Endothelium releases t-PA (tissue Plasminogen Activator)",
    "t-PA converts Plasminogen → Plasmin",
    "Plasmin degrades Fibrin clot → Fibrin Degradation Products (FDPs, D-dimer)",
    "Clot dissolved; vessel recanalised",
], fill=LIGHT_PURP, stroke=PURPLE))
story.append(Paragraph("C. Clinical Anticoagulants", sub_head))
story.append(tbl(
    ["Drug", "Mechanism"],
    [
        ["Heparin", "Activates ATIII; immediate effect; IV/SC; monitored by aPTT"],
        ["Warfarin", "Inhibits Vitamin K-dependent factors (II, VII, IX, X); monitored by PT/INR"],
        ["Aspirin", "Irreversibly inhibits COX → ↓ TXA₂ → anti-platelet"],
        ["tPA, Streptokinase", "Fibrinolytic agents — convert plasminogen to plasmin"],
    ],
    col_widths=[4*cm, 12.5*cm]
))
story.append(ref("Guyton & Hall, 14e, Ch.37"))
story.append(divider())

# ─── Q18: Bleeding Disorders ─────────────────────────────────────────────────
story.append(section_box("Q18. Bleeding Disorders [S3]", LIGHT_RED, RED))
story.append(tbl(
    ["Disorder", "Defect", "Lab Findings", "Features"],
    [
        ["Haemophilia A", "Factor VIII deficiency (X-linked recessive)",
         "↑ aPTT; PT normal", "Haemarthrosis, deep muscle bleeds; males affected"],
        ["Haemophilia B", "Factor IX deficiency (Christmas disease; X-linked)",
         "↑ aPTT; PT normal", "Same as Haem A; treat with Factor IX concentrate"],
        ["Von Willebrand disease", "vWF deficiency/dysfunction (AD)",
         "↑ BT; aPTT may ↑", "Mucosal bleeding, epistaxis, menorrhagia"],
        ["ITP", "Autoimmune platelet destruction (anti-GPIIb/IIIa)",
         "↓ Platelet count; BT ↑", "Petechiae, purpura; treat with steroids"],
        ["DIC", "Widespread activation of coagulation → clotting + bleeding",
         "↑ PT, ↑ aPTT, ↓ platelets, ↑ D-dimer", "Triggered by sepsis, obstetric emergencies"],
    ],
    col_widths=[3.5*cm, 4.5*cm, 3.5*cm, 5*cm]
))
story.append(ref("Guyton & Hall, 14e, Ch.37"))
story.append(divider())

# ─── Q19: ABO / Rh Incompatibility ──────────────────────────────────────────
story.append(section_box("Q19. Blood Grouping, Cross-Matching and Transfusion Reaction [S5]", LIGHT_BLUE, DARK_BLUE))
story.append(Paragraph("A. ABO Blood Groups", sub_head))
story.append(tbl(
    ["Blood Group", "Antigens on RBC", "Antibodies in Plasma", "Can Donate to", "Can Receive from"],
    [
        ["A", "A", "Anti-B", "A, AB", "A, O"],
        ["B", "B", "Anti-A", "B, AB", "B, O"],
        ["AB (Universal Recipient)", "A and B", "None", "AB only", "A, B, AB, O"],
        ["O (Universal Donor)", "None", "Anti-A and Anti-B", "A, B, AB, O", "O only"],
    ],
    col_widths=[3.5*cm, 3*cm, 3.5*cm, 3*cm, 3.5*cm]
))
story.append(Paragraph("B. Rh System", sub_head))
story.append(bullet([
    "Rh antigen (D antigen) — present in Rh+, absent in Rh-",
    "Rh- individual has NO anti-D naturally; sensitisation required",
    "First incompatible transfusion → sensitisation; Second → haemolytic transfusion reaction",
]))
story.append(Paragraph("C. Transfusion Reactions (ABO Incompatibility)", sub_head))
story.append(bullet([
    "Agglutination: donor RBCs clump → plugs small vessels",
    "Haemolysis: complement activation → intravascular haemolysis → haemoglobinaemia, haemoglobinuria",
    "Symptoms: fever, chills, back pain, haematuria, shock, renal failure",
    "Cross-matching: Donor RBCs + Recipient serum — must be NEGATIVE for safe transfusion",
]))
story.append(ref("Guyton & Hall, 14e, Ch.36"))
story.append(divider())

# ─── Q20: Erythroblastosis Foetalis ──────────────────────────────────────────
story.append(section_box("Q20. Erythroblastosis Foetalis [S5]", LIGHT_ORG, ORANGE))
story.append(simple_flowchart([
    "Rh⁻ mother × Rh⁺ father → Rh⁺ fetus",
    "During delivery: fetal Rh⁺ RBCs enter maternal circulation → sensitisation",
    "Mother produces IgG anti-D antibodies",
    "2nd Rh⁺ pregnancy: IgG anti-D crosses placenta (FcRn receptor) → attacks fetal RBCs",
    "Haemolysis → Anaemia → Compensatory extramedullary erythropoiesis (liver, spleen)",
    "Release of nucleated RBCs (Erythroblasts) into fetal blood",
    "Severe: Hydrops fetalis (oedema, ascites) → stillbirth",
    "High bilirubin after birth → Kernicterus (brain damage)",
], fill=LIGHT_ORG, stroke=ORANGE))
story.append(Paragraph("Prevention:", sub_head))
story.append(bullet([
    "Anti-D immunoglobulin (RhoGAM) given to Rh⁻ mother at 28 weeks and within 72h of delivery",
    "Prevents sensitisation by neutralising Rh⁺ fetal cells before immune response",
]))
story.append(Paragraph("Treatment:", sub_head))
story.append(bullet([
    "Intrauterine blood transfusion (for severe anaemia in fetus)",
    "Phototherapy after birth for jaundice",
    "Exchange transfusion for severe hyperbilirubinaemia",
]))
story.append(ref("Guyton & Hall, 14e, Ch.36"))
story.append(divider())

# ─── Q21: Hazards of Blood Transfusion ────────────────────────────────────────
story.append(section_box("Q21. Hazards of Blood Transfusion [S3]", LIGHT_RED, RED))
story.append(tbl(
    ["Type", "Examples"],
    [
        ["Immunological", "Haemolytic reactions (ABO/Rh), Febrile non-haemolytic, Urticaria, Anaphylaxis, TRALI, Transfusion-associated GvHD"],
        ["Infectious", "HIV, HCV, HBV, CMV, syphilis, malaria, variant CJD"],
        ["Metabolic", "Hypocalcaemia (citrate toxicity), Hyperkalaemia (stored blood), Acidosis, Hypothermia"],
        ["Volume overload", "TACO (Transfusion-Associated Circulatory Overload) → pulmonary oedema"],
        ["Massive transfusion", "Dilutional coagulopathy, thrombocytopaenia"],
    ],
    col_widths=[4.5*cm, 12*cm]
))
story.append(ref("Guyton & Hall, 14e, Ch.36"))
story.append(PageBreak())


# ══════════════════════════════════════════════════════════════════════════════
# SECTION 3 — MUSCLE
# ══════════════════════════════════════════════════════════════════════════════
story.append(chapter_header("SECTION 3: MUSCLE PHYSIOLOGY", GREEN))
story.append(Spacer(1, 0.3*cm))

# ─── Q22: Sarcomere ──────────────────────────────────────────────────────────
story.append(section_box("Q22. Sarcomere [S10]", LIGHT_GREEN, GREEN))
story.append(Paragraph("A. Definition", sub_head))
story.append(Paragraph(
    "The sarcomere is the basic contractile unit of skeletal muscle, extending from one Z-disc to the next. "
    "Length at rest: ~2.0–2.2 μm.", body))
story.append(Paragraph("B. Bands and Lines", sub_head))
story.append(tbl(
    ["Structure", "Description", "Contains"],
    [
        ["Z-disc (Z-line)", "Boundary of sarcomere", "Alpha-actinin; anchors thin filaments"],
        ["I-band", "Light band; bisected by Z-disc", "Thin (actin) filaments only"],
        ["A-band", "Dark band; remains constant in length", "Thick (myosin) + overlapping thin filaments"],
        ["H-zone", "Central pale zone of A-band", "Thick (myosin) filaments only"],
        ["M-line", "Centre of H-zone", "Myomesin, titin; anchors thick filaments"],
        ["Titin", "Elastic protein from M-line to Z-disc", "Prevents over-stretching"],
    ],
    col_widths=[3.5*cm, 5*cm, 8*cm]
))
story.append(Paragraph("C. Changes During Contraction (Sliding Filament Theory)", sub_head))
story.append(bullet([
    "I-band shortens (thin filaments slide in)",
    "H-zone shortens or disappears",
    "A-band length remains CONSTANT",
    "Z-discs come closer together",
    "Sarcomere length decreases",
]))
story.append(key_point("Mnemonic: A-band is Always constant; I-band and H-zone shorten"))
story.append(ref("Guyton & Hall, 14e, Ch.6; Ganong 26e, Ch.5"))
story.append(divider())

# ─── Q23: Contractile Proteins ───────────────────────────────────────────────
story.append(section_box("Q23. Contractile Proteins [S3]", LIGHT_TEAL, TEAL))
story.append(tbl(
    ["Protein", "Type", "Location", "Function"],
    [
        ["Myosin", "Thick filament", "A-band", "Motor protein; ATPase activity; forms cross-bridges with actin"],
        ["Actin", "Thin filament", "I-band + A-band overlap", "Binds myosin; has binding sites covered by tropomyosin"],
        ["Tropomyosin", "Regulatory", "Thin filament groove", "Blocks myosin binding sites on actin at rest"],
        ["Troponin T", "Regulatory", "Thin filament", "Binds tropomyosin"],
        ["Troponin I", "Regulatory", "Thin filament", "Inhibits actin-myosin interaction"],
        ["Troponin C", "Regulatory (Ca²⁺ sensor)", "Thin filament", "Binds Ca²⁺ → conformational change → exposes binding sites"],
        ["Titin", "Structural/elastic", "M-line to Z-disc", "Elasticity; prevents over-stretch"],
        ["Nebulin", "Structural", "Along thin filament", "Template for thin filament length"],
    ],
    col_widths=[3*cm, 3*cm, 3.5*cm, 7*cm]
))
story.append(ref("Guyton & Hall, 14e, Ch.6"))
story.append(divider())

# ─── Q24: Sarco-Tubular System ────────────────────────────────────────────────
story.append(section_box("Q24. Sarco-Tubular System [S10]", LIGHT_BLUE, DARK_BLUE))
story.append(tbl(
    ["Component", "Description", "Function"],
    [
        ["T-Tubules (Transverse tubules)",
         "Deep invaginations of sarcolemma at A-I junction (2 per sarcomere in skeletal)",
         "Conduct action potential rapidly deep into muscle fibre"],
        ["Sarcoplasmic Reticulum (SR)",
         "Specialised smooth ER surrounding myofibrils; terminal cisternae at ends",
         "Stores and releases Ca²⁺; SERCA pump resequestrates Ca²⁺"],
        ["Triad",
         "One T-tubule flanked by two terminal cisternae of SR",
         "Excitation-contraction coupling site"],
    ],
    col_widths=[4*cm, 5.5*cm, 7*cm]
))
story.append(Paragraph("Mechanism of Ca²⁺ Release:", sub_head))
story.append(simple_flowchart([
    "Action Potential along sarcolemma → enters T-tubule",
    "Activates DHPR (dihydropyridine receptor) — voltage sensor in T-tubule membrane",
    "DHPR activates RyR1 (ryanodine receptor) on SR membrane",
    "Ca²⁺ floods from SR into cytoplasm",
    "Ca²⁺ binds Troponin C → exposes actin binding sites → cross-bridge cycling",
    "Relaxation: SERCA pump resequestrates Ca²⁺ into SR; troponin-tropomyosin complex re-covers actin",
], fill=LIGHT_BLUE, stroke=MID_BLUE))
story.append(ref("Guyton & Hall, 14e, Ch.7; Ganong 26e, Ch.5"))
story.append(divider())

# ─── Q25: Molecular Basis of Contraction ────────────────────────────────────
story.append(section_box("Q25. Molecular Basis of Contraction (Cross-Bridge Cycle) [S5]", LIGHT_GREEN, GREEN))
story.append(simple_flowchart([
    "STEP 1: AP → Ca²⁺ release from SR → Ca²⁺ binds Troponin C",
    "STEP 2: Conformational change → Tropomyosin moves → Actin binding sites EXPOSED",
    "STEP 3: Myosin head (ADP+Pi attached) binds actin → Cross-bridge formed",
    "STEP 4: POWER STROKE — ADP+Pi released → myosin head tilts (45°→ 90°) → actin slides toward M-line",
    "STEP 5: ATP binds myosin head → Cross-bridge DETACHES from actin",
    "STEP 6: ATP hydrolysed (ATPase) → ADP+Pi → Myosin head re-cocked (90°) → ready for next cycle",
    "RELAXATION: Ca²⁺ re-pumped to SR by SERCA; Tropomyosin covers actin binding sites again",
], fill=LIGHT_GREEN, stroke=GREEN))
story.append(key_point("Rigor Mortis: No ATP → Cross-bridges cannot detach → muscles remain rigid"))
story.append(ref("Guyton & Hall, 14e, Ch.6; Ganong 26e, Ch.5"))
story.append(divider())

# ─── Q26: NM Junction ────────────────────────────────────────────────────────
story.append(section_box("Q26. Neuromuscular Junction (NMJ) [S10]", LIGHT_TEAL, TEAL))
story.append(Paragraph("A. Structure", sub_head))
story.append(bullet([
    "Synapse between motor neuron and skeletal muscle fibre",
    "Pre-synaptic terminal: contains ACh vesicles, mitochondria, active zones",
    "Synaptic cleft: ~50 nm; contains acetylcholinesterase",
    "Post-synaptic membrane (motor end plate): junctional folds, nicotinic ACh receptors (nAChR)",
]))
story.append(Paragraph("B. Sequence of Events at NMJ", sub_head))
story.append(simple_flowchart([
    "AP reaches motor nerve terminal",
    "Depolarisation → Ca²⁺ influx via VGCC (voltage-gated Ca²⁺ channels)",
    "Ca²⁺ triggers ACh vesicle exocytosis into synaptic cleft",
    "ACh binds nicotinic receptors (α-subunits) on motor end plate",
    "Na⁺ influx → End Plate Potential (EPP) generated",
    "EPP triggers AP in sarcolemma → T-tubule → Ca²⁺ release → contraction",
    "AChE in cleft breaks down ACh → Choline reuptake + Acetate",
]))
story.append(Paragraph("C. Pharmacology:", sub_head))
story.append(tbl(
    ["Drug", "Action", "Effect"],
    [
        ["Neostigmine, Physostigmine", "AChE inhibitor", "↑ ACh at NMJ → prolonged depolarisation"],
        ["Succinylcholine", "Depolarising blocker (NM agonist)", "Persistent depolarisation → flaccid paralysis"],
        ["Curare (d-tubocurarine)", "Non-depolarising blocker (competitive)", "Blocks nAChR → flaccid paralysis"],
        ["Botulinum toxin", "Inhibits ACh vesicle fusion", "Flaccid paralysis"],
    ],
    col_widths=[4.5*cm, 4.5*cm, 7.5*cm]
))
story.append(ref("Guyton & Hall, 14e, Ch.7; Ganong 26e, Ch.6"))
story.append(divider())

# ─── Q27: Muscle Tone ────────────────────────────────────────────────────────
story.append(section_box("Q27. Muscle Tone [S5]", LIGHT_PURP, PURPLE))
story.append(bullet([
    "Muscle tone = state of slight, continuous partial contraction of muscle at rest",
    "Due to asynchronous firing of motor units",
    "Maintained by stretch reflex via muscle spindles (Ia afferents) → α-motor neurons",
    "CNS control: cerebellum and basal ganglia regulate tone",
]))
story.append(tbl(
    ["Condition", "Tone", "Cause", "Features"],
    [
        ["Hypotonia", "Decreased", "LMN lesion, cerebellum disease", "Flaccid muscles, hyporeflexia"],
        ["Hypertonia", "Increased", "UMN lesion", "Spasticity (UMNL) or Rigidity (basal ganglia)"],
        ["Spasticity", "↑ (velocity-dependent)", "UMN lesion (stroke, spinal cord)", "Clasp-knife rigidity"],
        ["Rigidity", "↑ (throughout ROM)", "Parkinson's disease", "Cogwheel / lead-pipe rigidity"],
    ],
    col_widths=[3*cm, 2.5*cm, 4.5*cm, 6.5*cm]
))
story.append(ref("Guyton & Hall, 14e, Ch.55"))
story.append(divider())

# ─── Q28: Refractory Period ──────────────────────────────────────────────────
story.append(section_box("Q28. Refractory Period [S3]", LIGHT_BLUE, DARK_BLUE))
story.append(tbl(
    ["Type", "Duration", "Mechanism", "Response to Stimulus"],
    [
        ["Absolute Refractory Period (ARP)",
         "~1–2 ms (nerve); ~250 ms (cardiac)",
         "Na⁺ channels inactivated (h-gate closed); no AP possible",
         "No response to any stimulus"],
        ["Relative Refractory Period (RRP)",
         "Several ms after ARP",
         "Na⁺ channels partially recovered; membrane hyperpolarised (K⁺ efflux)",
         "Only supra-threshold stimulus can generate AP"],
        ["Supernormal Period",
         "After RRP",
         "Membrane slightly depolarised (close to threshold)",
         "Easier to fire"],
    ],
    col_widths=[3.5*cm, 3*cm, 5*cm, 5*cm]
))
story.append(key_point("ARP prevents tetanic contraction in cardiac muscle — essential for pumping"))
story.append(ref("Guyton & Hall, 14e, Ch.5; Ganong 26e, Ch.4"))
story.append(divider())

# ─── Q29: AP Curve ────────────────────────────────────────────────────────────
story.append(section_box("Q29. Action Potential Curve [S3]", LIGHT_GREEN, GREEN))
story.append(tbl(
    ["Phase", "Change", "Ion responsible"],
    [
        ["Resting Membrane Potential", "–70 mV (nerve), –90 mV (muscle)", "K⁺ dominates; Na⁺-K⁺ ATPase maintains gradient"],
        ["Threshold", "–55 mV", "Sufficient Na⁺ channels open"],
        ["Depolarisation (Phase 0)", "–70 → +30 mV (overshoot)", "Na⁺ influx (VG Na⁺ channels open)"],
        ["Repolarisation", "+30 → –70 mV", "K⁺ efflux (VG K⁺ channels open); Na⁺ channels inactivate"],
        ["After-hyperpolarisation", "<–70 mV briefly", "K⁺ channels slow to close"],
        ["Restoration", "Return to RMP", "Na⁺-K⁺ ATPase restores gradients"],
    ],
    col_widths=[4*cm, 4*cm, 8.5*cm]
))
story.append(key_point("All-or-None Law: AP is either fully generated or not; amplitude does not vary with stimulus intensity"))
story.append(ref("Guyton & Hall, 14e, Ch.5; Costanzo 7e, Ch.1"))
story.append(divider())

# ─── Q30: Heat, Rigor & Mortis ────────────────────────────────────────────────
story.append(section_box("Q30. Heat, Rigor Mortis and Contracture [S3]", LIGHT_ORG, ORANGE))
story.append(Paragraph("Heat in Muscle Contraction:", sub_head))
story.append(bullet([
    "Initial Heat: produced during contraction (activation heat + heat of shortening)",
    "Recovery Heat: produced after contraction during aerobic resynthesis of ATP",
    "Total Energy = Initial heat + Recovery heat + Mechanical work",
]))
story.append(Paragraph("Rigor Mortis:", sub_head))
story.append(bullet([
    "Definition: post-mortem stiffening of muscles",
    "Cause: ATP depletion → cross-bridges cannot detach → permanent rigor complex",
    "Onset: 2–6 hours after death; complete by 12 hours",
    "Passes off: 24–48 hours when autolytic enzymes destroy cross-bridges",
    "Heat Rigor: Hb and proteins denature at high temperatures → irreversible contracture",
]))
story.append(ref("Ganong 26e, Ch.5"))
story.append(divider())

# ─── Q31: Myasthenia Gravis ──────────────────────────────────────────────────
story.append(section_box("Q31. Myasthenia Gravis [S10]", LIGHT_RED, RED))
story.append(Paragraph("A. Definition:", sub_head))
story.append(Paragraph(
    "Autoimmune disorder where antibodies against post-synaptic nicotinic ACh receptors (nAChR) "
    "at NMJ cause progressive fatigable muscle weakness.", body))
story.append(Paragraph("B. Pathophysiology:", sub_head))
story.append(simple_flowchart([
    "Anti-nAChR IgG antibodies produced (Thymus — role in antigen presentation)",
    "Antibodies bind nAChR on motor end plate",
    "Complement activation → destruction of junctional folds",
    "Reduced functional nAChRs → smaller EPP",
    "EPP may fall below threshold → no AP → No contraction",
    "Repeated stimulation → progressive EPP decline → FATIGABLE WEAKNESS",
], fill=LIGHT_RED, stroke=RED))
story.append(Paragraph("C. Clinical Features:", sub_head))
story.append(bullet([
    "Fatigable ptosis (drooping of eyelid worsens with use)",
    "Diplopia, dysarthria, dysphagia",
    "Proximal limb weakness, worse at end of day",
    "Myasthenic crisis: respiratory failure (life-threatening)",
]))
story.append(Paragraph("D. Investigations:", sub_head))
story.append(bullet([
    "Anti-AChR antibodies (positive in 85%)",
    "Edrophonium (Tensilon) test: short-acting AChE inhibitor → temporary improvement",
    "Decremental response on repetitive nerve stimulation (EMG)",
    "CT chest: Thymoma (15%)",
]))
story.append(Paragraph("E. Treatment:", sub_head))
story.append(bullet([
    "Pyridostigmine (AChE inhibitor) — first line",
    "Steroids / Immunosuppressants (azathioprine)",
    "Thymectomy (especially if thymoma present)",
    "Plasmapheresis / IVIG for crisis",
]))
story.append(ref("Guyton & Hall, 14e, Ch.7; Ganong 26e, Ch.6"))
story.append(PageBreak())


# ══════════════════════════════════════════════════════════════════════════════
# SECTION 4 — DIGESTIVE SYSTEM
# ══════════════════════════════════════════════════════════════════════════════
story.append(chapter_header("SECTION 4: DIGESTIVE SYSTEM", TEAL))
story.append(Spacer(1, 0.3*cm))

# ─── Q32: Nerve Supply to GIT ────────────────────────────────────────────────
story.append(section_box("Q32. Nerve Supply to GIT [S5]", LIGHT_TEAL, TEAL))
story.append(tbl(
    ["Division", "Nerves", "Function"],
    [
        ["Extrinsic Parasympathetic",
         "Vagus nerve (CN X) — to oesophagus to transverse colon\nPelvic nerves (S2,3,4) — to descending colon to rectum",
         "↑ GI motility and secretion; ↓ sphincter tone"],
        ["Extrinsic Sympathetic",
         "Greater splanchnic (T5-9) → celiac plexus\nLesser splanchnic (T10-11) → superior mesenteric\nLeast splanchnic (T12) → inferior mesenteric",
         "↓ GI motility and secretion; ↑ sphincter tone; vasoconstriction"],
        ["Enteric Nervous System (Intrinsic)",
         "Auerbach's (myenteric) plexus — between circular and longitudinal muscle\nMeissner's (submucosal) plexus — in submucosa",
         "Controls all GI motility and secretion independently; 'Second Brain'"],
    ],
    col_widths=[3.5*cm, 5.5*cm, 7.5*cm]
))
story.append(ref("Guyton & Hall, 14e, Ch.63; Ganong 26e, Ch.26"))
story.append(divider())

# ─── Q33: Saliva ─────────────────────────────────────────────────────────────
story.append(section_box("Q33. Composition and Functions of Saliva [S3]", LIGHT_GREEN, GREEN))
story.append(Paragraph("A. Composition (daily volume: 1–1.5 L/day; pH 6.0–7.4)", sub_head))
story.append(tbl(
    ["Component", "Source / Notes"],
    [
        ["Salivary amylase (Ptyalin)", "Parotid gland; begins starch digestion (α-1,4 bonds)"],
        ["Lingual lipase", "Serous glands of tongue; fat digestion starts in mouth"],
        ["Mucin (Mucus)", "Sublingual + submandibular; lubrication"],
        ["IgA (secretory)", "Antibacterial; passive immunity"],
        ["Lysozyme", "Antimicrobial enzyme; cleaves bacterial cell wall"],
        ["Lactoferrin", "Binds iron; bacteriostatic"],
        ["Bicarbonate (HCO₃⁻)", "Neutralises acid; protects teeth"],
        ["Kallikrein", "Produces bradykinin → vasodilation"],
        ["Water", "~99%"],
    ],
    col_widths=[5*cm, 11.5*cm]
))
story.append(Paragraph("B. Functions of Saliva:", sub_head))
story.append(numbered([
    "Digestion: amylase begins starch hydrolysis",
    "Lubrication: mucin facilitates swallowing",
    "Antibacterial: IgA, lysozyme, lactoferrin",
    "Solvent: dissolves food chemicals for taste",
    "pH regulation: HCO₃⁻ neutralises acid",
    "Oral hygiene: washes food particles",
    "Speech: moistens mouth",
]))
story.append(ref("Guyton & Hall, 14e, Ch.64; Ganong 26e, Ch.26"))
story.append(divider())

# ─── Q34: Gastric Juice ─────────────────────────────────────────────────────
story.append(section_box("Q34. Composition and Functions of Gastric Juice [S3]", LIGHT_BLUE, DARK_BLUE))
story.append(tbl(
    ["Component", "Cell of origin", "Function"],
    [
        ["HCl", "Parietal (Oxyntic) cells", "Kills bacteria; converts pepsinogen → pepsin; denatures proteins; provides acid environment"],
        ["Pepsinogen", "Chief (Peptic) cells", "Activated by HCl → Pepsin; begins protein digestion"],
        ["Intrinsic Factor (IF)", "Parietal cells", "Essential for Vit B12 absorption in terminal ileum"],
        ["Mucus", "Mucous neck cells + surface mucus cells", "Protects gastric mucosa from acid; bicarbonate barrier"],
        ["Gastric lipase", "Chief cells", "Begins fat digestion (limited)"],
        ["Gastrin", "G cells (antrum)", "Stimulates HCl secretion and gastric motility"],
    ],
    col_widths=[3.5*cm, 4.5*cm, 8.5*cm]
))
story.append(key_point("H⁺-K⁺-ATPase (proton pump) in parietal cells is the final step in HCl secretion; inhibited by PPIs"))
story.append(ref("Guyton & Hall, 14e, Ch.65"))
story.append(divider())

# ─── Q35: Secretion of Gastric Juice (Guyton) + Phases ─────────────────────
story.append(section_box("Q35. Secretion of Gastric Juice — Guyton & Phases of Gastric Secretion [S5]", LIGHT_ORG, ORANGE))
story.append(Paragraph("Phases of Gastric Secretion:", sub_head))
story.append(tbl(
    ["Phase", "Stimulus", "Mechanism", "% of Total Secretion"],
    [
        ["Cephalic Phase",
         "Sight, smell, taste, thought of food",
         "Via Vagus nerve (CN X) → ACh → stimulates parietal and chief cells",
         "~30%"],
        ["Gastric Phase",
         "Food in stomach; distension; amino acids, peptides",
         "Gastrin released from G cells (antrum); Vagal reflex; Histamine (ECL cells via H₂ receptors)",
         "~60%"],
        ["Intestinal Phase",
         "Chyme enters duodenum",
         "Initial: intestinal gastrin stimulates; Late: secretin, CCK, GIP inhibit",
         "~10%"],
    ],
    col_widths=[3*cm, 4.5*cm, 6.5*cm, 2.5*cm]
))
story.append(Paragraph("Stimulants of HCl secretion:", sub_head))
story.append(bullet([
    "Gastrin (via CCK-B receptors on parietal cells)",
    "Histamine (via H₂ receptors on parietal cells — most potent stimulus)",
    "ACh (via M₃ receptors on parietal cells)",
]))
story.append(Paragraph("Inhibitors of HCl secretion:", sub_head))
story.append(bullet([
    "Secretin — released when duodenal pH < 2",
    "CCK (cholecystokinin) — from duodenum",
    "GIP (gastric inhibitory peptide) — fat in duodenum",
    "Somatostatin — from D cells",
]))
story.append(ref("Guyton & Hall, 14e, Ch.65"))
story.append(divider())

# ─── Q36: Pancreatic Juice ──────────────────────────────────────────────────
story.append(section_box("Q36. Composition, Functions and Regulation of Pancreatic Juice [S3]", LIGHT_TEAL, TEAL))
story.append(Paragraph("A. Composition (Volume: 1.5–2 L/day; pH 8–8.3)", sub_head))
story.append(tbl(
    ["Enzyme", "Precursor", "Function"],
    [
        ["Trypsin", "Trypsinogen → activated by Enterokinase",
         "Cleaves peptide bonds at Arg/Lys; activates other zymogens"],
        ["Chymotrypsin", "Chymotrypsinogen → activated by Trypsin",
         "Cleaves at aromatic/bulky amino acids"],
        ["Elastase", "Proelastase", "Cleaves elastin"],
        ["Carboxypeptidase A & B", "Procarboxypeptidase", "Exopeptidases — cleave from C-terminal"],
        ["Pancreatic amylase", "—", "Digests starch → maltose + dextrins"],
        ["Pancreatic lipase", "—", "Digests triglycerides → monoglycerides + fatty acids"],
        ["Colipase", "—", "Cofactor for lipase; anchors lipase to lipid droplets"],
        ["Phospholipase A₂", "—", "Digests phospholipids"],
        ["Ribonuclease/DNase", "—", "Digests RNA/DNA"],
        ["Bicarbonate (HCO₃⁻)", "— (from ductal cells)", "Neutralises acid chyme; pH 8.3; essential for enzyme activity"],
    ],
    col_widths=[3.5*cm, 3.5*cm, 9.5*cm]
))
story.append(Paragraph("B. Regulation:", sub_head))
story.append(tbl(
    ["Stimulus", "Hormone", "Effect on Pancreas"],
    [
        ["Acid chyme in duodenum (pH<4.5)", "Secretin (S-cells)", "↑↑ HCO₃⁻ secretion (water + bicarbonate)"],
        ["Fats + Proteins in duodenum", "CCK (I-cells)", "↑↑ Enzyme secretion"],
        ["Vagal stimulation (cephalic phase)", "ACh", "↑ Enzyme secretion (minor)"],
        ["Somatostatin", "D-cells", "↓ Pancreatic secretion"],
    ],
    col_widths=[4.5*cm, 3*cm, 9*cm]
))
story.append(ref("Guyton & Hall, 14e, Ch.66; Ganong 26e, Ch.26"))
story.append(divider())

# ─── Q37: Bile and Bile Salts ────────────────────────────────────────────────
story.append(section_box("Q37. Functions of Bile and Bile Salts [S5]", LIGHT_BLUE, DARK_BLUE))
story.append(Paragraph("A. Composition of Bile (produced 700–1000 mL/day):", sub_head))
story.append(tbl(
    ["Component", "Notes"],
    [
        ["Bile salts", "Chenodeoxycholic + Cholic acid conjugated with glycine/taurine; 50%"],
        ["Phospholipids (Lecithin)", "Solubilises cholesterol in bile"],
        ["Cholesterol", "End product of cholesterol metabolism"],
        ["Bilirubin glucuronide", "Main bile pigment; gives bile yellow-green colour"],
        ["Electrolytes", "Na⁺, Cl⁻, HCO₃⁻"],
        ["Water", "~95%"],
    ],
    col_widths=[4.5*cm, 12*cm]
))
story.append(Paragraph("B. Functions of Bile Salts:", sub_head))
story.append(numbered([
    "Emulsification of fats: reduce large fat globules to small droplets → ↑ surface area for lipase",
    "Micelle formation: solubilise lipid digestion products (fatty acids, monoglycerides) for absorption",
    "Activation of pancreatic lipase",
    "Enterohepatic circulation: 94% reabsorbed in terminal ileum → portal vein → liver",
    "Cholesterol excretion: primary route for cholesterol elimination",
]))
story.append(Paragraph("C. Functions of Bile itself:", sub_head))
story.append(bullet([
    "Excretion of bilirubin, cholesterol, drug metabolites",
    "Neutralises acid chyme (with HCO₃⁻)",
    "Fat-soluble vitamin (A, D, E, K) absorption",
]))
story.append(ref("Guyton & Hall, 14e, Ch.66"))
story.append(divider())

# ─── Q38: Jaundice ──────────────────────────────────────────────────────────
story.append(section_box("Q38. Jaundice [S5]", LIGHT_ORG, ORANGE))
story.append(Paragraph(
    "Jaundice (Icterus) = yellowish discolouration of skin, sclera, and mucous membranes due to "
    "raised serum bilirubin (>2 mg/dL).", body))
story.append(tbl(
    ["Feature", "Pre-hepatic (Haemolytic)", "Hepatic (Hepatocellular)", "Post-hepatic (Obstructive)"],
    [
        ["Cause", "Excess RBC destruction", "Liver cell damage", "Bile duct obstruction"],
        ["Examples", "Haemolytic anaemia, malaria, G6PD deficiency",
         "Viral hepatitis, cirrhosis, drugs",
         "Gallstone, Ca pancreas, cholangiocarcinoma"],
        ["Bilirubin type", "↑ Unconjugated", "↑ Both", "↑ Conjugated"],
        ["Urine bilirubin", "Absent", "Present", "Present (dark urine)"],
        ["Urine urobilinogen", "↑↑ (↑ haem breakdown)", "↑ or Normal", "Absent or ↓"],
        ["Stool colour", "Dark (↑ stercobilin)", "Normal or pale", "Pale/clay-coloured"],
        ["Liver enzymes", "Normal", "↑ ALT, AST", "↑ ALP, GGT"],
        ["Pruritus", "Absent", "Variable", "Present (↑ bile salts in skin)"],
    ],
    col_widths=[3*cm, 4*cm, 4.5*cm, 5*cm]
))
story.append(ref("Guyton & Hall, 14e, Ch.71"))
story.append(divider())

# ─── Q39: Deglutition ────────────────────────────────────────────────────────
story.append(section_box("Q39. Deglutition (Swallowing) [S10]", LIGHT_GREEN, GREEN))
story.append(Paragraph("Deglutition = process of swallowing; has 3 phases:", sub_head))
story.append(tbl(
    ["Phase", "Voluntary/Reflex", "Events"],
    [
        ["Oral/Buccal Phase",
         "VOLUNTARY",
         "Tongue pushes bolus backward to pharynx; lips closed; soft palate pressed against teeth"],
        ["Pharyngeal Phase",
         "REFLEX (mediated by swallowing centre in medulla)",
         "Soft palate closes nasopharynx; larynx elevates; epiglottis closes laryngeal inlet; UES opens; peristaltic wave carries bolus to oesophagus; breathing briefly stops"],
        ["Oesophageal Phase",
         "REFLEX (enteric + vagal)",
         "Primary peristalsis carries bolus; LES relaxes; gravity assists upright; if bolus remains → secondary peristalsis (distension-induced)"],
    ],
    col_widths=[3.5*cm, 3.5*cm, 9.5*cm]
))
story.append(key_point("Dysphagia to solids first → mechanical obstruction; Dysphagia to liquids first → neuromuscular disorder"))
story.append(ref("Guyton & Hall, 14e, Ch.64; Ganong 26e, Ch.26"))
story.append(divider())

# ─── Q40: Movements of Stomach ──────────────────────────────────────────────
story.append(section_box("Q40. Movements of the Stomach [S3]", LIGHT_TEAL, TEAL))
story.append(tbl(
    ["Movement", "Location", "Function"],
    [
        ["Receptive Relaxation",
         "Fundus",
         "Vagally-mediated relaxation of fundus when food enters → accommodation; ↑ volume without ↑ pressure"],
        ["Tonic Contractions",
         "Body",
         "Slow sustained contractions → mix food and propel toward antrum"],
        ["Peristaltic Waves",
         "Body → Antrum",
         "3 waves/min; propulsive force; mix chyme with gastric juice; driven by pacemaker cells in corpus"],
        ["Retropulsion",
         "Antrum + Pylorus",
         "Pylorus closes before complete emptying → chyme bounces back → trituration (mechanical grinding)"],
        ["Systolic Contractions (Pyloric pump)",
         "Antrum",
         "Strong peristaltic contractions every 20s squirt small amounts (1–7 mL) into duodenum"],
    ],
    col_widths=[4*cm, 3*cm, 9.5*cm]
))
story.append(ref("Guyton & Hall, 14e, Ch.64"))
story.append(divider())

# ─── Q41: Emptying of Stomach ────────────────────────────────────────────────
story.append(section_box("Q41. Gastric Emptying [S5]", LIGHT_BLUE, DARK_BLUE))
story.append(Paragraph("A. Factors that PROMOTE gastric emptying:", sub_head))
story.append(bullet([
    "Distension of stomach (→ antral pump activated)",
    "Gastrin hormone",
    "Motilin hormone",
    "Liquid / semi-liquid contents",
]))
story.append(Paragraph("B. Factors that INHIBIT gastric emptying (Enterogastric Reflex):", sub_head))
story.append(bullet([
    "Fats in duodenum → CCK → powerful inhibition",
    "Acid in duodenum (pH<3.5) → Secretin → inhibition",
    "Hyperosmotic solutions in duodenum → osmoreceptors → inhibition",
    "Protein/fats → GIP → inhibition",
    "Pain, stress (via SNS)",
]))
story.append(Paragraph("C. Half-emptying times:", sub_head))
story.append(bullet([
    "Water: ~10–20 min",
    "Mixed meal: ~3–4 hours",
    "Fats: longest (4–5 hours)",
]))
story.append(ref("Guyton & Hall, 14e, Ch.64"))
story.append(divider())

# ─── Q42: Vomiting ──────────────────────────────────────────────────────────
story.append(section_box("Q42. Vomiting [S5]", LIGHT_RED, RED))
story.append(Paragraph("A. Definition & Control Centre:", sub_head))
story.append(bullet([
    "Vomiting = forceful expulsion of gastric/intestinal contents through mouth",
    "Controlled by Vomiting Centre in reticular formation of medulla",
    "Chemoreceptor Trigger Zone (CTZ): area postrema, floor of 4th ventricle — lacks blood-brain barrier; responds to drugs, toxins",
]))
story.append(Paragraph("B. Causes (Act on CTZ or Vomiting Centre):", sub_head))
story.append(bullet([
    "GI irritation (gastroenteritis, peptic ulcer, obstruction)",
    "Motion sickness (vestibular-cerebellar pathway)",
    "Drugs: opioids, chemotherapy, digoxin, levodopa (act on CTZ via D₂/5-HT₃ receptors)",
    "Pregnancy (hCG stimulates CTZ)",
    "Raised ICP (stimulates VC directly)",
    "Uraemia, DKA (metabolic triggers via CTZ)",
]))
story.append(Paragraph("C. Act of Vomiting — Sequence:", sub_head))
story.append(simple_flowchart([
    "Deep inspiration → Glottis closes (prevents aspiration)",
    "Soft palate elevates → closes nasopharynx",
    "Diaphragm + Abdominal muscles contract forcefully → ↑ intra-abdominal pressure",
    "LES relaxes + Cardia of stomach opens",
    "Reverse peristalsis from small intestine → stomach → oesophagus",
    "Stomach contents expelled through mouth",
], fill=LIGHT_RED, stroke=RED))
story.append(Paragraph("D. Complications of Vomiting:", sub_head))
story.append(bullet([
    "Metabolic alkalosis (loss of H⁺ and Cl⁻)",
    "Hypokalaemia",
    "Dehydration",
    "Mallory-Weiss tear (mucosal tear at gastro-oesophageal junction)",
    "Aspiration pneumonia",
]))
story.append(ref("Guyton & Hall, 14e, Ch.64; Ganong 26e, Ch.26"))
story.append(divider())

# ─── Q43: Movements of Small Intestine ──────────────────────────────────────
story.append(section_box("Q43. Movements of Small Intestine [S10]", LIGHT_TEAL, TEAL))
story.append(tbl(
    ["Movement", "Type", "Description", "Function"],
    [
        ["Segmentation",
         "Non-propulsive (mixing)",
         "Circular muscle contracts in segments; 12/min duodenum, 8/min ileum; controlled by Auerbach's plexus + slow waves",
         "Mixes chyme with digestive juices; maximises contact with mucosa for absorption"],
        ["Peristalsis",
         "Propulsive",
         "Coordinated circular + longitudinal contractions; 'law of intestine'; moves aboral",
         "Propels chyme from duodenum → ileum"],
        ["Pendular movements",
         "Propulsive (partial)",
         "To and fro motion; common in small intestine",
         "Mixing"],
        ["Migrating Motor Complex (MMC)",
         "Interdigestive",
         "Powerful peristaltic waves every 90 min during fasting; from stomach → terminal ileum",
         "Housekeeping; clears debris and bacteria between meals"],
        ["Villous movements",
         "Local",
         "Rhythmic shortening/lengthening of intestinal villi",
         "Empties lacteals and venous capillaries; aids absorption"],
    ],
    col_widths=[3.5*cm, 3*cm, 5.5*cm, 4.5*cm]
))
story.append(ref("Guyton & Hall, 14e, Ch.64; Ganong 26e, Ch.26"))
story.append(divider())

# ─── Q44: Defecation ────────────────────────────────────────────────────────
story.append(section_box("Q44. Defecation [S5]", LIGHT_PURP, PURPLE))
story.append(simple_flowchart([
    "Colonic mass movements propel faeces into rectum",
    "Distension of rectum → Rectal pressure >25 mmHg → stretch receptors activated",
    "Signals via pelvic nerves to sacral spinal cord (S2,3,4) and cerebral cortex",
    "DEFECATION REFLEX (Intrinsic): Relaxation of internal anal sphincter (IAS); contraction of rectal walls",
    "CONSCIOUS CONTROL: If appropriate → External anal sphincter (EAS) relaxed (voluntary)",
    "VALSALVA MANOEUVRE: Deep breath → glottis closed → diaphragm + abd muscles contract → ↑ intra-abdominal pressure",
    "Puborectalis relaxes → anorectal angle straightens",
    "Faeces expelled",
], fill=LIGHT_PURP, stroke=PURPLE))
story.append(tbl(
    ["Sphincter", "Innervation", "Control"],
    [
        ["Internal Anal Sphincter (IAS)", "Autonomic (involuntary smooth muscle)", "Normally closed; relaxed by rectal distension (rectoanal inhibitory reflex)"],
        ["External Anal Sphincter (EAS)", "Pudendal nerve (S2,3,4) — somatic/voluntary", "Voluntarily contracted to defer defecation or relaxed to permit it"],
    ],
    col_widths=[4.5*cm, 4.5*cm, 7.5*cm]
))
story.append(ref("Guyton & Hall, 14e, Ch.64"))
story.append(divider())

# ─── Q45: Function of Liver ──────────────────────────────────────────────────
story.append(section_box("Q45. Functions of the Liver [S2]", LIGHT_GREEN, GREEN))
story.append(tbl(
    ["Category", "Functions"],
    [
        ["Metabolic",
         "Carbohydrate metabolism (glycogenesis, glycogenolysis, gluconeogenesis)\n"
         "Fat metabolism (β-oxidation, ketogenesis, lipogenesis, VLDL synthesis)\n"
         "Protein metabolism (transamination, deamination, urea synthesis)"],
        ["Secretory", "Bile production (700 mL/day); bile salts synthesis"],
        ["Synthetic",
         "Plasma proteins (albumin, globulins, fibrinogen, clotting factors I, II, V, VII, IX, X)\n"
         "Hormone synthesis (IGF-1, angiotensinogen, thrombopoietin)"],
        ["Detoxification",
         "Drug and toxin metabolism (Phase I: CYP450 oxidation; Phase II: conjugation)\n"
         "Alcohol metabolism (alcohol dehydrogenase)\n"
         "Ammonia → Urea (urea cycle)"],
        ["Storage",
         "Glycogen (2-day supply)\nFat-soluble vitamins (A, D, E, K) and B12\nIron (ferritin, haemosiderin)\nCopper"],
        ["Excretory", "Bilirubin, cholesterol, drug metabolites → bile"],
        ["Immune",
         "Kupffer cells (hepatic macrophages) — phagocytose bacteria from portal blood"],
        ["Endocrine",
         "Converts T4 → T3 (active thyroid hormone)\n25-hydroxylation of Vit D3\nDegradation of hormones (insulin, glucagon, steroids)"],
        ["Haematopoiesis",
         "Foetal haematopoiesis (6–7 weeks); produces EPO"],
    ],
    col_widths=[4*cm, 12.5*cm]
))
story.append(ref("Guyton & Hall, 14e, Ch.71"))

# ─── Final page ───────────────────────────────────────────────────────────────
story.append(PageBreak())
end_data = [[Paragraph("END OF ANSWER KEY", ParagraphStyle(
    "end", fontSize=20, textColor=WHITE, alignment=TA_CENTER,
    fontName="Helvetica-Bold"))]]
end_tbl = Table(end_data, colWidths=[W - 3.6*cm])
end_tbl.setStyle(TableStyle([
    ("BACKGROUND", (0,0), (-1,-1), DARK_BLUE),
    ("TOPPADDING",    (0,0), (-1,-1), 20),
    ("BOTTOMPADDING", (0,0), (-1,-1), 20),
]))
story.append(Spacer(1, 5*cm))
story.append(end_tbl)
story.append(Spacer(1, 0.5*cm))
story.append(Paragraph(
    "References: Guyton & Hall Textbook of Medical Physiology (14e) · "
    "Ganong's Review of Medical Physiology (26e) · Costanzo Physiology (7e)",
    S("Normal", fontSize=10, textColor=MID_BLUE, alignment=TA_CENTER)))
story.append(Spacer(1,0.3*cm))
story.append(Paragraph(
    "Best of luck for your Prelims Examination! 🎓",
    S("Normal", fontSize=12, textColor=GREEN, alignment=TA_CENTER,
      fontName="Helvetica-Bold")))

# ══════════════════════════════════════════════════════════════════════════════
# BUILD
# ══════════════════════════════════════════════════════════════════════════════
doc.build(story)
print("PDF generated successfully!")

cd /home/daytona/workspace/physiology-exam && python gen_pdf.py 2>&1

~/physiology-exam/gen_pdf.py

Successfully replaced 1 instance(s) of the string in '/home/daytona/workspace/physiology-exam/gen_pdf.py'

cd /home/daytona/workspace/physiology-exam && python gen_pdf.py 2>&1

"body.clone" in ~/physiology-exam

~/physiology-exam/gen_pdf.py

Successfully replaced 1 instance(s) of the string in '/home/daytona/workspace/physiology-exam/gen_pdf.py'

cd /home/daytona/workspace/physiology-exam && python gen_pdf.py 2>&1

~/physiology-exam/gen_pdf.py

Successfully replaced 1 instance(s) of the string in '/home/daytona/workspace/physiology-exam/gen_pdf.py'

cd /home/daytona/workspace/physiology-exam && python gen_pdf.py 2>&1

ls -lh /home/daytona/workspace/physiology-exam/Physiology_Prelims_Answers.pdf