Gastric Secretion Flashcards
What are the cells called that produce slow waves (waves of de and repolarisation)?
Interstitial cells of Cajal found in between nerve plexuses and smooth muscle layers
What are the functions of peristaltic and segmental contractions?
Peristaltic-moving the food forward
Segmental-mixing the food up
What do the cells of the gastric gland produce and secrete?
Mucous neck cell-mucous
Chief cell-pepsinogen and gastric lipase
Parietal Cell-hydrochloric acid and intrinsic factor
G cells-gastrin
What is the main dietary component digested by the stomach?
Protein
What is the stimulus for gastrin secretion and inhibitor of gastrin secretion?
Peptides and amino acids stimulate release
Somatostatin inhibits the release
What is the function of gastrin?
Stimulates gastric acid secretion (so found in stomach)
What is the stimulant for CCK release?
Fatty acids and amino acids stimulate release
What is the function of CCK?
Stimulates gallbladder contraction and pancreatic enzyme secretion. Inhibits gastric emptying and acid secretion. Promotes satiety
What is the stimulant for secretin secretion?
Acid in small intestine promotes secretion
What is the action of secretin?
Stimulates bicarb secretion and inhibits gastric emptying and acid secretion
What is the stimulus for motilin secretion and inhibition of secretion?
Fasting secretes
Eating a meal inhibits release
What is the action of motilin?
Stimulates migrating motor complex (when the tract is mainly empty to sweep any leftover food or bacteria into the large intestine)
What are the roles of gastric mucous?
Protects mucosal surface from mechanical injury Neutral pH (HCO3) so protects against gastric acid corrosion and pepsin digestion
What are the functions of gastric acid?
Releases pepsin from pepsinogen which acts on proteins
Triggers somatostatin from D cells
Breaks proteins down to secondary structure from tertiary so that pepsin can act more readily on them
Kills bacteria
Inactivates salivary amylase stopping carbohydrate digestion
What are the three paracrine secretions from the gastric mucosa?
Histamine (from ECL cells)
Somatostatin
Intrinsic factor
