Pancreatic Juice - Composition, Secretion, Regulation, and Function

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, KeepTogether
)
from reportlab.lib.enums import TA_CENTER, TA_LEFT, TA_JUSTIFY
from reportlab.pdfbase import pdfmetrics
from reportlab.pdfbase.ttfonts import TTFont

OUTPUT = "/home/daytona/workspace/pancreatic-juice/Pancreatic_Juice_Study_Guide.pdf"

# ── Colour palette ──────────────────────────────────────────────
NAVY       = colors.HexColor("#1B3A6B")
TEAL       = colors.HexColor("#0D7C8A")
LIGHT_TEAL = colors.HexColor("#E0F4F6")
AMBER      = colors.HexColor("#F5A623")
LIGHT_AMB  = colors.HexColor("#FFF4E0")
LIGHT_GREY = colors.HexColor("#F4F6F8")
MED_GREY   = colors.HexColor("#BDC3CC")
WHITE      = colors.white
RED_SOFT   = colors.HexColor("#C0392B")
GREEN_SOFT = colors.HexColor("#1A7A4A")
PURPLE     = colors.HexColor("#6C3483")
LIGHT_PURP = colors.HexColor("#F5EEF8")

# ── Styles ───────────────────────────────────────────────────────
base = getSampleStyleSheet()

def S(name, **kw):
    return ParagraphStyle(name, **kw)

TITLE    = S("TITLE",    fontSize=22, textColor=WHITE,   alignment=TA_CENTER,
             fontName="Helvetica-Bold", leading=28, spaceAfter=4)
SUBTITLE = S("SUBTITLE", fontSize=11, textColor=LIGHT_TEAL, alignment=TA_CENTER,
             fontName="Helvetica", leading=14, spaceAfter=2)

SEC_HDR  = S("SEC_HDR",  fontSize=13, textColor=WHITE,   fontName="Helvetica-Bold",
             leading=16, leftIndent=4)
SUB_HDR  = S("SUB_HDR",  fontSize=11, textColor=NAVY,    fontName="Helvetica-Bold",
             leading=14, spaceBefore=6, spaceAfter=2)
BODY     = S("BODY",     fontSize=9,  textColor=colors.HexColor("#2C3E50"),
             fontName="Helvetica",     leading=13, spaceAfter=2, alignment=TA_JUSTIFY)
BULLET   = S("BULLET",   fontSize=9,  textColor=colors.HexColor("#2C3E50"),
             fontName="Helvetica",     leading=12, leftIndent=12, spaceAfter=2,
             bulletIndent=4)
SMALL    = S("SMALL",    fontSize=8,  textColor=colors.HexColor("#555"),
             fontName="Helvetica-Oblique", leading=10, alignment=TA_CENTER)
KEYBOX   = S("KEYBOX",   fontSize=9,  textColor=NAVY,    fontName="Helvetica-Bold",
             leading=12, alignment=TA_CENTER)
WARN     = S("WARN",     fontSize=9,  textColor=RED_SOFT, fontName="Helvetica-Bold",
             leading=12, leftIndent=8)
TH_STYLE = S("TH",       fontSize=8,  textColor=WHITE,   fontName="Helvetica-Bold",
             leading=11, alignment=TA_CENTER)
TD_STYLE = S("TD",       fontSize=8,  textColor=colors.HexColor("#2C3E50"),
             fontName="Helvetica",     leading=11, alignment=TA_CENTER)
TD_LEFT  = S("TD_LEFT",  fontSize=8,  textColor=colors.HexColor("#2C3E50"),
             fontName="Helvetica",     leading=11, alignment=TA_LEFT)

# ── Helper: section banner ────────────────────────────────────────
def section_banner(text, colour=NAVY):
    data = [[Paragraph(text, SEC_HDR)]]
    t = Table(data, colWidths=[17*cm])
    t.setStyle(TableStyle([
        ("BACKGROUND", (0,0), (-1,-1), colour),
        ("ROUNDEDCORNERS", [4]),
        ("TOPPADDING",    (0,0), (-1,-1), 6),
        ("BOTTOMPADDING", (0,0), (-1,-1), 6),
        ("LEFTPADDING",   (0,0), (-1,-1), 10),
    ]))
    return t

def key_box(items, colour=LIGHT_TEAL, border=TEAL):
    """Horizontal row of key-point pills."""
    row = [Paragraph(i, KEYBOX) for i in items]
    widths = [17*cm / len(items)] * len(items)
    t = Table([row], colWidths=widths)
    t.setStyle(TableStyle([
        ("BACKGROUND",    (0,0), (-1,-1), colour),
        ("BOX",           (0,0), (-1,-1), 1.2, border),
        ("INNERGRID",     (0,0), (-1,-1), 0.5, border),
        ("TOPPADDING",    (0,0), (-1,-1), 5),
        ("BOTTOMPADDING", (0,0), (-1,-1), 5),
        ("ALIGN",         (0,0), (-1,-1), "CENTER"),
        ("VALIGN",        (0,0), (-1,-1), "MIDDLE"),
    ]))
    return t

def make_table(headers, rows, col_widths, alt_colour=LIGHT_GREY):
    data = [[Paragraph(h, TH_STYLE) for h in headers]]
    for i, row in enumerate(rows):
        styled = []
        for j, cell in enumerate(row):
            style = TD_LEFT if j == 0 else TD_STYLE
            styled.append(Paragraph(str(cell), style))
        data.append(styled)
    t = Table(data, colWidths=col_widths)
    style_cmds = [
        ("BACKGROUND",    (0,0), (-1,0),  NAVY),
        ("ROWBACKGROUNDS",(0,1), (-1,-1), [WHITE, alt_colour]),
        ("BOX",           (0,0), (-1,-1), 0.8, MED_GREY),
        ("INNERGRID",     (0,0), (-1,-1), 0.4, MED_GREY),
        ("TOPPADDING",    (0,0), (-1,-1), 4),
        ("BOTTOMPADDING", (0,0), (-1,-1), 4),
        ("LEFTPADDING",   (0,0), (-1,-1), 5),
        ("RIGHTPADDING",  (0,0), (-1,-1), 5),
        ("VALIGN",        (0,0), (-1,-1), "MIDDLE"),
    ]
    t.setStyle(TableStyle(style_cmds))
    return t

def highlight_box(text, bg=LIGHT_AMB, border=AMBER):
    data = [[Paragraph(text, BODY)]]
    t = Table(data, colWidths=[17*cm])
    t.setStyle(TableStyle([
        ("BACKGROUND",    (0,0), (-1,-1), bg),
        ("BOX",           (0,0), (-1,-1), 1.5, border),
        ("LEFTPADDING",   (0,0), (-1,-1), 10),
        ("RIGHTPADDING",  (0,0), (-1,-1), 10),
        ("TOPPADDING",    (0,0), (-1,-1), 6),
        ("BOTTOMPADDING", (0,0), (-1,-1), 6),
    ]))
    return t

# ── Build document ───────────────────────────────────────────────
doc = SimpleDocTemplate(
    OUTPUT, pagesize=A4,
    leftMargin=2*cm, rightMargin=2*cm,
    topMargin=1.8*cm, bottomMargin=1.8*cm,
    title="Pancreatic Juice - Study Guide",
    author="Orris Medical"
)

story = []
SP = lambda n=4: Spacer(1, n)
HR = lambda: HRFlowable(width="100%", thickness=0.5, color=MED_GREY, spaceAfter=4)

# ════════════════════════════════════════════════════════════════
# COVER HEADER
# ════════════════════════════════════════════════════════════════
cover_data = [[
    Paragraph("🫀 PANCREATIC JUICE", TITLE),
    Paragraph("Composition · Secretion · Regulation · Function", SUBTITLE),
    Paragraph("Physiology Revision Guide  |  Based on Guyton, Ganong & Costanzo", SUBTITLE),
]]
cover_t = Table(cover_data, colWidths=[17*cm])
cover_t.setStyle(TableStyle([
    ("BACKGROUND",    (0,0), (-1,-1), NAVY),
    ("TOPPADDING",    (0,0), (-1,-1), 14),
    ("BOTTOMPADDING", (0,0), (-1,-1), 14),
    ("LEFTPADDING",   (0,0), (-1,-1), 12),
    ("RIGHTPADDING",  (0,0), (-1,-1), 12),
    ("ROUNDEDCORNERS",[6]),
]))
story += [cover_t, SP(10)]

# Quick-facts strip
story += [
    key_box(["~1,500 mL / day", "pH 7.8 – 8.4", "Isosmotic with plasma",
             "Secreted by exocrine pancreas", "Empties into duodenum"]),
    SP(10)
]

# ════════════════════════════════════════════════════════════════
# SECTION 1 – COMPOSITION
# ════════════════════════════════════════════════════════════════
story += [section_banner("1.  COMPOSITION OF PANCREATIC JUICE", NAVY), SP(6)]

story += [Paragraph("<b>A. Aqueous (Electrolyte) Component</b> — secreted by centroacinar & ductal cells", SUB_HDR)]
story += [
    Paragraph("• <b>HCO<sub>3</sub><sup>–</sup>:</b>  ~113 mEq/L  (plasma = 24 mEq/L) — the hallmark ion, responsible for alkalinity", BULLET),
    Paragraph("• <b>Na<sup>+</sup>, K<sup>+</sup>:</b>  approximately equal to plasma concentrations", BULLET),
    Paragraph("• <b>Cl<sup>–</sup>:</b>  inversely related to HCO<sub>3</sub><sup>–</sup>  (rises when flow rate falls)", BULLET),
    Paragraph("• Fluid is <b>isosmotic</b> with plasma throughout the physiological flow range", BULLET),
    SP(4)
]

story += [Paragraph("<b>B. Enzymatic Component</b> — secreted by acinar cells as inactive zymogens", SUB_HDR)]

enz_headers = ["Category", "Zymogen / Inactive Form", "Active Enzyme", "Action"]
enz_rows = [
    ["Proteolytic", "Trypsinogen",        "Trypsin",          "Cleaves proteins → peptides (endo)"],
    ["",            "Chymotrypsinogen",   "Chymotrypsin",     "Cleaves aromatic AA peptide bonds"],
    ["",            "Procarboxypeptidase","Carboxypeptidase",  "Releases free amino acids (exo)"],
    ["",            "Proelastase",        "Elastase",          "Digests elastin & other proteins"],
    ["Amylolytic",  "—  (active)",        "Pancreatic amylase","Starch/glycogen → disaccharides"],
    ["Lipolytic",   "—  (active)",        "Pancreatic lipase", "Triglycerides → FA + monoglyceride"],
    ["",            "—  (active)",        "Cholesterol esterase","Cholesterol esters → cholesterol + FA"],
    ["",            "Prophospholipase A2","Phospholipase A2",  "Phospholipids → lyso-phospholipid + FA"],
    ["Nucleolytic", "—  (active)",        "DNase / RNase",     "Digests DNA and RNA"],
]
story += [make_table(enz_headers, enz_rows, [2.5*cm, 3.8*cm, 3.8*cm, 6.9*cm]), SP(6)]

story += [
    highlight_box(
        "<b>Trypsin Inhibitor:</b>  Also secreted by acinar cells; neutralises any trypsin "
        "prematurely activated inside the pancreas, preventing autodigestion. "
        "Inadequate inhibitor activity is a proposed trigger in acute pancreatitis.",
        bg=LIGHT_PURP, border=PURPLE
    ),
    SP(8)
]

# ════════════════════════════════════════════════════════════════
# SECTION 2 – MECHANISM OF SECRETION
# ════════════════════════════════════════════════════════════════
story += [section_banner("2.  MECHANISM OF SECRETION", TEAL), SP(6)]

story += [Paragraph("<b>A. Enzymatic Secretion (Acinar Cells)</b>", SUB_HDR)]
story += [
    Paragraph("1.  Enzymes are synthesised on <b>rough ER</b>, processed in <b>Golgi</b>, and stored as <b>zymogen granules</b>.", BULLET),
    Paragraph("2.  On stimulation (CCK / ACh), zymogen granules fuse with apical membrane and undergo <b>exocytosis</b>.", BULLET),
    Paragraph("3.  Proteases are released in <b>inactive form</b> to protect the acinar cell from autodigestion.", BULLET),
    SP(4)
]

story += [Paragraph("<b>B. Aqueous / Bicarbonate Secretion (Centroacinar + Ductal Cells)</b>", SUB_HDR)]
story += [
    Paragraph("1.  <b>Carbonic anhydrase</b> inside ductal cells: CO<sub>2</sub> + H<sub>2</sub>O → H<sub>2</sub>CO<sub>3</sub> → H<sup>+</sup> + HCO<sub>3</sub><sup>–</sup>", BULLET),
    Paragraph("2.  <b>HCO<sub>3</sub><sup>–</sup></b> is secreted into the duct lumen via a <b>Cl<sup>–</sup>/HCO<sub>3</sub><sup>–</sup> exchanger</b> (CFTR recycles Cl<sup>–</sup>).", BULLET),
    Paragraph("3.  <b>H<sup>+</sup></b> is exported basolaterally via <b>Na<sup>+</sup>/H<sup>+</sup> exchanger</b>.", BULLET),
    Paragraph("4.  <b>Na<sup>+</sup></b> enters the lumen by co-transport and through paracellular tight junctions.", BULLET),
    Paragraph("5.  Water follows osmotically → isotonic NaHCO<sub>3</sub> solution.", BULLET),
    SP(4)
]

story += [
    highlight_box(
        "<b>Flow-rate effect on composition:</b>  At HIGH flow rates (e.g., after secretin), "
        "HCO<sub>3</sub><sup>–</sup> concentration rises and Cl<sup>–</sup> falls — less time for exchange in large ducts. "
        "At LOW flow rates, HCO<sub>3</sub><sup>–</sup> is reabsorbed for Cl<sup>–</sup>, so Cl<sup>–</sup> predominates.",
        bg=LIGHT_TEAL, border=TEAL
    ),
    SP(8)
]

# ════════════════════════════════════════════════════════════════
# SECTION 3 – ACTIVATION CASCADE
# ════════════════════════════════════════════════════════════════
story += [section_banner("3.  ACTIVATION OF PROTEOLYTIC ENZYMES", colors.HexColor("#5D4037")), SP(6)]

story += [
    Paragraph(
        "Proteolytic enzymes are secreted as <b>inactive zymogens</b> and activated sequentially in the "
        "intestinal lumen — a safety mechanism preventing pancreatic autodigestion.",
        BODY
    ),
    SP(4)
]

cascade_headers = ["Step", "Event", "Enzyme Involved"]
cascade_rows = [
    ["1", "Duodenal brush-border enzyme Enterokinase cleaves trypsinogen",               "Enterokinase → Trypsin"],
    ["2", "Trypsin autocatalytically activates more trypsinogen",                         "Trypsin → Trypsin"],
    ["3", "Trypsin activates chymotrypsinogen",                                           "Trypsin → Chymotrypsin"],
    ["4", "Trypsin activates procarboxypeptidase",                                        "Trypsin → Carboxypeptidase"],
    ["5", "Trypsin activates proelastase",                                                "Trypsin → Elastase"],
    ["6", "Trypsin activates prophospholipase A2",                                        "Trypsin → Phospholipase A2"],
]
story += [make_table(cascade_headers, cascade_rows, [1*cm, 10*cm, 6*cm]), SP(6)]

story += [
    highlight_box(
        "<b>⚠ Clinical Correlation – Acute Pancreatitis:</b>  Premature activation of trypsin "
        "WITHIN the pancreatic duct initiates the cascade of autodigestion. "
        "Serum <b>amylase</b> and <b>lipase</b> rise markedly — used for diagnosis. "
        "Phospholipase A2 activation generates lyso-phosphatidylcholine, which damages cell membranes.",
        bg=colors.HexColor("#FDEDEC"), border=RED_SOFT
    ),
    SP(8)
]

# ════════════════════════════════════════════════════════════════
# SECTION 4 – FUNCTIONS
# ════════════════════════════════════════════════════════════════
story += [section_banner("4.  FUNCTIONS OF PANCREATIC JUICE", GREEN_SOFT), SP(6)]

fn_headers = ["Function", "Component Responsible", "Detail"]
fn_rows = [
    ["Neutralise gastric acid",   "HCO₃⁻ (aqueous component)",    "Raises duodenal pH from ~2 to 6–7; jejunal pH → nearly neutral"],
    ["Protein digestion",         "Trypsin, chymotrypsin, carboxypeptidase, elastase", "Endopeptidases + exopeptidase; complete digestion to amino acids"],
    ["Carbohydrate digestion",    "Pancreatic amylase",            "Starch/glycogen → disaccharides & trisaccharides (not cellulose)"],
    ["Fat digestion",             "Lipase, cholesterol esterase, phospholipase A2", "Triglycerides, cholesterol esters, and phospholipids hydrolysed"],
    ["Nucleic acid digestion",    "DNase, RNase",                  "Breaks down dietary DNA and RNA"],
    ["Enable lipase activity",    "HCO₃⁻ neutralisation",         "Pancreatic lipases are inactivated at low pH; neutralisation is prerequisite"],
]
story += [make_table(fn_headers, fn_rows, [3.8*cm, 5.5*cm, 7.7*cm]), SP(8)]

# ════════════════════════════════════════════════════════════════
# SECTION 5 – REGULATION
# ════════════════════════════════════════════════════════════════
story += [section_banner("5.  REGULATION OF PANCREATIC SECRETION", colors.HexColor("#6A1B9A")), SP(6)]

story += [Paragraph("<b>A. Hormonal Regulation (Intestinal Phase)</b>", SUB_HDR)]

reg_headers = ["Stimulus", "Stimulus Source", "Secreted by", "Target Cell", "2nd Messenger", "Effect on Juice"]
reg_rows = [
    ["H⁺ (acidic chyme)",        "Duodenal lumen", "S cells (duodenum/jejunum)", "Ductal cells",  "cAMP ↑",        "Large volume, high HCO₃⁻, low enzyme"],
    ["Amino acids, fatty acids,\nsmall peptides", "Duodenal lumen", "I cells (duodenum/jejunum)", "Acinar cells", "IP₃ / Ca²⁺ ↑", "Enzyme-rich, low volume"],
]
story += [make_table(reg_headers, reg_rows, [2.8*cm, 2.5*cm, 3.2*cm, 2.5*cm, 2.5*cm, 3.5*cm])]
story += [
    SP(4),
    Paragraph(
        "<b>Potentiation:</b>  CCK and secretin act synergistically (multiplicative effect) — "
        "together they ensure enzymes are produced AND flushed into the duodenum by the aqueous component.",
        BODY
    ),
    SP(6)
]

story += [Paragraph("<b>B. Neural Regulation</b>", SUB_HDR)]
story += [
    Paragraph("• <b>Parasympathetic (vagus / ACh):</b> Acts on acinar cells via IP₃/Ca²⁺ (same pathway as CCK); stimulates enzyme secretion; potentiates CCK effect.", BULLET),
    Paragraph("• <b>Sympathetic:</b> Inhibits pancreatic secretion.", BULLET),
    Paragraph("• <b>Conditioned reflex:</b> Sight/smell of food → vagally mediated enzyme secretion (cephalic phase).", BULLET),
    SP(6)
]

story += [Paragraph("<b>C. Inhibitory Mediators</b>", SUB_HDR)]
story += [
    Paragraph("• <b>Peptide YY</b> (from ileal endocrine cells): signals end of intestinal phase; inhibits secretion ('ileal brake').", BULLET),
    Paragraph("• <b>Somatostatin:</b> general inhibitor of GI secretions, including pancreatic juice.", BULLET),
    Paragraph("• <b>Sympathetic activity:</b> direct inhibition.", BULLET),
    SP(8)
]

# ════════════════════════════════════════════════════════════════
# SECTION 6 – PHASES
# ════════════════════════════════════════════════════════════════
story += [section_banner("6.  PHASES OF PANCREATIC SECRETION", AMBER), SP(6)]

phase_headers = ["Phase", "% of Total", "Stimulus", "Mediator", "Type of Juice"]
phase_rows = [
    ["Cephalic", "~20%",    "Sight, smell, taste, thought of food", "Vagus nerve (ACh)",         "Mainly enzyme-rich; small volume"],
    ["Gastric",  "~5–10%",  "Gastric distension",                  "Vagovagal reflex (ACh)",    "Mainly enzyme-rich; small volume"],
    ["Intestinal","~70–80%","Acidic chyme, AA, fatty acids in duodenum","Secretin + CCK + ACh",  "Both enzymatic AND aqueous; copious"],
]
story += [make_table(phase_headers, phase_rows, [2*cm, 1.8*cm, 4.8*cm, 4.4*cm, 4*cm], alt_colour=LIGHT_AMB), SP(8)]

# ════════════════════════════════════════════════════════════════
# SECTION 7 – HIGH-YIELD MEMORY AIDS
# ════════════════════════════════════════════════════════════════
story += [section_banner("7.  HIGH-YIELD MEMORY AIDS", colors.HexColor("#C0392B")), SP(6)]

story += [
    Paragraph("<b>Mnemonic — Pancreatic Enzymes: 'TCC PLCD'</b>", SUB_HDR),
    Paragraph("T – Trypsin  |  C – Chymotrypsin  |  C – Carboxypeptidase  |  "
              "P – (Pro)elastase  |  L – Lipase  |  C – Cholesterol esterase  |  D – DNase/RNase", BODY),
    SP(4)
]

story += [
    Paragraph("<b>Key Numbers to Remember</b>", SUB_HDR),
    key_box(["1,500 mL/day", "pH 8.0", "HCO₃⁻ 113 mEq/L", "Intestinal phase 70–80%"]),
    SP(6)
]

story += [
    Paragraph("<b>Secretin vs CCK — Quick Contrast</b>", SUB_HDR),
    make_table(
        ["Feature", "Secretin", "CCK"],
        [
            ["Trigger",          "H⁺ (acid) in duodenum",         "Amino acids, fatty acids, small peptides"],
            ["Secreted by",      "S cells",                        "I cells"],
            ["Target",           "Ductal cells",                   "Acinar cells"],
            ["2nd messenger",    "cAMP",                           "IP₃ / Ca²⁺"],
            ["Juice produced",   "High volume, high HCO₃⁻, low enzyme", "Low volume, enzyme-rich"],
            ["Also stimulates",  "Bile secretion",                 "Gallbladder contraction"],
        ],
        [4*cm, 6.5*cm, 6.5*cm]
    ),
    SP(8)
]

# Footer note
story += [
    HR(),
    Paragraph(
        "Sources: Guyton & Hall Textbook of Medical Physiology 14e  |  "
        "Ganong's Review of Medical Physiology 26e  |  Costanzo Physiology 7e",
        SMALL
    ),
    SP(2),
    Paragraph("Generated by Orris Medical AI  •  For revision purposes only", SMALL),
]

# ── Build ────────────────────────────────────────────────────────
doc.build(story)
print(f"PDF saved to: {OUTPUT}")