COMPOSITION OF GASTRIC JUICE(ACID)

• Gastric acid is a digestive fluid, formed in the stomach.
• It is composed of..
• Potassium chloride (KCl)
• Sodium chloride (NaCl)
• Hydrochloric acid (HCl)

Cell types responsible for secreting gastric acid:

Mucous neck cells, found in the upper, or “neck,” regions of the glands, produce a thin, soluble mucus

Parietal cells - found mainly in the middle region of the glands, simultaneously secrete hydrochloric acid (HCl) and intrinsic factor. This structure provides a huge surface area for secreting H and Cl into the stomach lumen. HCl makes the stomach contents extremely acidic (pH 1.5–3.5), a condition necessary for activation and optimal activity of pepsin.

Chief cells occur mainly in the basal regions of the gastric glands. The chief cells produce pepsinogen, the inactive form of the protein-digesting enzyme pepsin.

Enteroendocrine cells - (“gut endocrine”), typically located deep in the gastric glands, release a variety of chemical messengers directly into the interstitial fluid of the lamina propria.

How gastric secretion and motility of stomach are regulated:
1.Reflex phase (cephalic): few minutes prior to food entry: smell/taste
2.Gastric phase: 3–4 hours after food enters the stomach
3.Intestinal phase: brief stimulatory effect as chyme enters the duodenum, followed by inhibitory effects