GI physiology Flashcards
Which hormones delay gastric emptying?
Gastric inhibitory peptide
CCK
enteroglucagon
Which hormones increase gastric emptying?
Gastrin
What proportion of acid is produced in the cephalic phase of digestion?
30%
Vagal cholinergic stimulation –> HCl secretion + gastrin release from G cells
What proportion of acid is produced in the gastric phase of digestion?
60%
Stomach distention/low H+/peptides –> gastrin release
What proportion of acid is produced in the intestinal phase of digestion?
10%
High acidity/distention/hypertonic solutions in the duodenum inhibits gastric acid secretion via CKK, secretin + neural reflexes
Where is gastrin produced?
G cells in stomach antrum, duodenum
What is the action of gastrin?
Stimulates HCl + IF production from parietal cells
Stimulates pepsin from chief cells
Promotes gastric + intestinal motility, mucosal growth
Where is CCK produced?
I cells duodenum + jejunum
What is the action of CCK?
Stimulates gallbladder contraction Stimulates release of pancreatic enzymes Relaxes Sphincter of Oddi Induces satiety decreases gastric emptying
What stimulates CCK?
Partially digested proteins + triglycerides
What stimulates gastrin?
Distention of stomach
What inhibits gastrin?
Low pH, somatostatin
Where is secretin produced?
S cells - duodenum, jejunum
What is the action of secretin?
Stimulates bicarbonate release from pancreas
Trophic affect pancreatic acing cells
Decreases gastric acid secretion
Where is vasoactive intestinal peptide produced (VIP)?
enteric nerves
What is the action of vasoactive intestinal peptide (VIP_?
Increases water and electrolyte secretion from the pancreas + gut.
relaxes smooth muscle of gut
Where is somatostatin produced?
D cells of pancreas, stomach + small intestine
What stimulates somatostatin release?
Fat, bile salts, glucose in intestinal lumen
What is the action of somtastatin?
Inhibits most GI hormones incl. production of Hcl, pepsin, gastrin, pancreatic enzymes, glucagon
Stimulates gastric mucous production
which cells produce glucagon?
alpha cells islets of langerhans
which cells produce somatostatin?
D cells pancreas
what is the main component absorbed by the colon?
Sodium (then water)
what is the calorie requirement in a severely unwell patient?
35 kcal/kg/day
what is the nitrogen requirement in a severely unwell patient?
0.3-3.5g N/kg/day
