Secretion of hcl by gastric parital cells and it's circulation give me

Secretion of hcl by gastric parital cells and it's circulation give me a flowchart and diagram in a easy understanding way

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Here is the complete visual guide! First, the official textbook diagram:

HCl Secretion by Parietal Cell - Molecular Diagram

And the full interactive flowchart + diagrams file:

HCl Secretion Parietal Cell

HTML File · HTML

HCl Secretion by Gastric Parietal Cells - Complete Guide

Part 1: Overview Flowchart

STIMULUS (meal / smell / taste / vagal reflex / stomach distension)
            │
            ▼
┌───────────────────────────────────────────────────┐
│        3 SECRETAGOGUES (act together)             │
│  HISTAMINE   +   ACETYLCHOLINE   +   GASTRIN      │
│  (ECL cells)     (Vagus / CN X)   (G cells→blood)│
│  H₂ receptor     M₃ receptor      CCK-B receptor  │
│  → cAMP/PKA      → IP₃/Ca²⁺      → IP₃/Ca²⁺     │
└───────────────────────────────────────────────────┘
            │
            ▼
  Parietal cell ACTIVATED
  Tubulovesicles fuse → canaliculi expand
  H⁺/K⁺-ATPase moves to apical membrane
            │
            ▼
  CO₂ (from blood) + H₂O
        ↓ [Carbonic Anhydrase]
    H₂CO₃ → H⁺ + HCO₃⁻
            │
     ┌──────┴──────┐
     ▼             ▼
H⁺/K⁺-ATPase    Cl⁻ channel (CFTR)
H⁺ pumped OUT   Cl⁻ secreted OUT
K⁺ taken IN     (into canaliculus)
(then recycled)
     └──────┬──────┘
            ▼
     H⁺ + Cl⁻ = HCl in LUMEN
     (~150 mmol/L, pH 1–2)
            │
            ▼
  HCO₃⁻ exits via AE2 (basolateral)
  exchanges for Cl⁻ entering the cell
            │
            ▼
  HCO₃⁻ → BLOOD = "ALKALINE TIDE"
  (postprandial venous alkalosis)

Part 2: Ionic Circulation - Step by Step

Step	What moves	Direction	Transporter	Why
1	CO₂	Blood → Cell	Diffusion	Raw material
2	CO₂ + H₂O → H⁺ + HCO₃⁻	Inside cell	Carbonic anhydrase	Makes H⁺
3	H⁺	Cell → Lumen	H⁺/K⁺-ATPase (uses ATP)	Acidifies stomach
4	K⁺	Lumen → Cell	Same H⁺/K⁺-ATPase	Exchanged for H⁺
5	K⁺	Cell → Lumen	K⁺ channel (uniporter)	Recycled to keep pump running
6	Cl⁻	Cell → Lumen	Cl⁻ channel / CFTR	Pairs with H⁺ to form HCl
7	H⁺ + Cl⁻	In lumen	-	HCl formed
8	HCO₃⁻	Cell → Blood	AE2 antiporter (basolateral)	Alkaline tide
9	Cl⁻	Blood → Cell	Same AE2 (exchange)	Replenishes Cl⁻ for step 6

Part 3: Three Phases of Secretion

Phase	% Output	Trigger	Mechanism
Cephalic	~30%	Sight, smell, taste, anticipation	Vagus → ACh → parietal cells + ECL + G cells
Gastric	~60%	Food in stomach, distension, peptides	G cells → gastrin → blood → parietal cells (largest phase)
Intestinal	~10%	Chyme enters duodenum	Duodenal G cells; quickly inhibited by secretin/CCK

Part 4: Inhibition

Somatostatin (D cells): released when pH < 3 - inhibits G cells and parietal cells directly
Secretin (S cells): released when acid enters duodenum - blocks gastrin and HCl
GIP: released by fat/glucose in duodenum - inhibits parietal cells
PPIs (omeprazole): irreversibly block H⁺/K⁺-ATPase (covalent binding)
H₂ blockers (cimetidine): block H₂ receptors - also kill histamine-potentiated ACh/gastrin effects
Atropine: blocks M₃ receptors

Quick Memory Aid - "HACK"

Histamine → cAMP/PKA
Acetylcholine → IP₃/Ca²⁺
Carbonic anhydrase → CO₂ + H₂O → H⁺ + HCO₃⁻
K⁺ recycled by the pump to keep it running
Alkaline Tide = HCO₃⁻ floods the blood after every meal

Key numbers: HCl in lumen ~150 mmol/L | pH ~1–2 | 3×10⁴ H⁺ ions/sec per parietal cell | H⁺ concentration is 3,000,000x higher than in blood.

Histology: A Text and Atlas (Pawlina), Fig. 17.11
Medical Physiology (Boron & Boulpaep), Fig. 42-4
Costanzo Physiology 7th ed., pp. 366-368

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