gastric juice regulation/ cells

Esophagus

Has all four elementary Canal layers (adventitia instead of serosa)

Gastroesophageal /cardiac sphincter keeps cardial orifice closed when not swallowing

Blood supply to stomach

Celiac trunk/gastric

Veins of hepatic portal system

Regions of stomach

Cardia around cardial orifice

Fund us

Body

Pylorus

Greater/lesser curvature

Functions of stomach

• mix saliva, food, gastric juice to form chyme

• secrets, gastric juice

• secretes gastrin into blood

What gastric juice contains 4

HCL

Pepsin

Intrinsic factor

Gastric lipase

Function of HCL

Denatures proteins, activates pepsinogen into Pepsin

breaks down plant cell walls kills bacteria

Function of Pepsin

Breakdown proteins into smaller peptides and amino acids

The function of intrinsic factor

A glycoprotein needed for vitamin B12 absorption in small intestine

Needed for RBC to mature

Function of gastric lipase

An enzyme that breaks down lipids

Gastrin

Hormone that controls release of acid in the stomach

Secreted by stomach and into blood when food is present

Gland cells in the stomach

Mucus neck cells

Parietal cells

Chief cells

Enteroendocrine cells

Mucus neck cells

Secrete, thin, acidic mucus

parietal cells

Secretes HCL and intrinsic factor

Chief cells

Secretes pepsinogen and lipases

Enteroendocrine cells

Secret hormones into lamina propria

• somatostatin

• Gastrin

Somatostatin

Inhibit stomach acid secretion/slows down digestion

Peptic/gastric ulcer

Causes erosion and wall of stomach

If perforate wall, hemorrhage can occur or peritonitis

Most caused by helicobacter pylori or NSAIDS

Two ways mucosa secretion of gastric juice is regulated

1.Neural mechanisms

• Vagus nerve stimulation

• Sympathetic stimulation

2.Hormonal mechanisms

• gastrin

Vagus nerve stimulation effect on gastric juice

Increases secretion of gastric juice

Sympathetic stimulation effect on gastric juice

Decreases secretion of gastric juice

Hormonal mechanism gastric juice secretion

Gastrin stimulate secretion of HCL

3 phases of gastric secretion regulation

1. Cephalic/reflex phase

2. Gastric phase

3. Intestinal phase

Cephalic/reflex phase

Conditioned reflex phase triggered by smell, sight taste, and thoughts

Gastric phase

Distention activates stretch receptors initiating reflexes

Chemical stimuli like partially digested proteins, caffeine, low acidity, activate G cells to secrete gastrin

• causes HCL to be released

Inhibition of gastric phase

3-4 hrs long, 2/3 of gastric juice releases

Intestinal phase

Stimulated by partially digested food entering small intestine; brief release of intestinal gastrin

Inhibited by distention of duodenum, presence of acidic chyme, fatty or hypertonic chyme

• enterogastric reflex

• enterogastrones (cells)

enterogastrones

enteroendocrine cells in dual denim that release two inhibiting hormones

• secretin

• Cholecystokinin

Secretin function

Stimulates secretion of bile and pancreatic juices; inhibits gastric gland secretion

Cholecystokinin Function

Stimulates, pancreatic juice secretions rich in digestive enzymes

Causes bile ejection of gallbladder, opening the sphincter of Oddi, and in this is satiety