Gastric secretion Flashcards
What is the function of the body of the stomach?
o Storage o Mucus o HCl – protein acid hydrolysis o Pepsinogen o Intrinsic factor
What is the function of the antrum of the stomach?
o Mixing/grinding => chyme
o Gastrin
What cell types are found in gastric glands?
- Mucous neck cells - Mucus
- Chief cells - Pepsinogens
- Parietal cells - HCl + Intrinsic factor
What are the 3 main stimulatory pathways for gastric acid production?
Gastrin
Histamine
Acetylcholine
What receptor does histamine bind to on the stomach yo cause acid secretion?
H2 receptor (Gas coupled)
What is the inhibitory pathway of gastric acid secretion initiated by?
Prostaglandins
What controls gastric acid secretion?
o Neurocrine (vagus/local reflexes) o Endocrine (gastrin) o Paracrine (histamine)
What % of gastric secretion is associated with the cephalic phase?
20%
How does ingested food stimulate gastric secretion in the gastric phase?
Stretches stomach
Gastric contents stimulating receptors
What are the two reflexes associated with stretching of the stomach?
Stretch activates two reflexes:
- a short reflex mediated through the myenteric nerve plexus
- a long reflex mediated through the vagus nerves and brainstem
What is the function of gastrin?
Stimulates acid secretion
What are enterogastrones?
Hormones released from gland cells in duodenal mucosa:
• Secretin
• Cholecystokinin (CCK)
• GIP
What are the two effects of enterogastrones?
- Inhibit gastric acid secretion
* Reduce gastric emptying (inhibit motility/contract pyloric sphincter)
What causes the release of enterogastrones?
Released in response to acid, hypertonic solutions, fatty acids or monoglycerides in duodenum i.e. stomach is emptying
What controls pepsin activity in the stomach?
pH = stored as zymogen (pepsinogen) in stomach at neutral pH, when pH drops as becomes more acidic, pepsin is formed
