GI Phys DSA

Question 1

Gastrin

Answer 1

Site of secretion: G cells of stomach
Stimuli of secretion: small peptides & A.A’s, distention of stomach, vagal stimulation
Actions: increase in gastric H secretion, stimulates growth of gastric mucosa

Question 2

Cholecystokinin (CCK)

Answer 2

Site of secretion: I cells of the duodenum and jejunum
Stimuli of secretion: small peptides and A.A’s, fatty acids
Actions: increase in pancreatic enzyme and HCO3 secretion, stimulates contraction of the gallbladder and relaxation of sphincter of Oddi, stimulates growth of exocrine pancreas and gallbladder
Inhibits gastric emptying

Question 3

Secretin

Answer 3

Site of secretion: S cells of duodenum
Stimuli of secretion: H in the duodenum, fatty acids in the duodenum
Actions: increase in pancreatic HCO3 secretion, biliary HCO3 secretion, gastric H secretion
Inhibits trophic effect of gastric on gastric muscosa

Question 4

Glucose-dependent insulinotrophic peptide (GIP)

Answer 4

Site of secretion: duodenum and jejunum
Stimuli of secretion: fatty acids, AA’s, oral glucose
Actions: increase insulin secretion from pancreatic B cells. Decrease gastric H secretion

Question 5

Somatostatin

Answer 5

Site of secretion: D cells of GI mucosa
Stimuli of secretion: decrease in luminal pH
Actions: inhibits gastric H secretion, inhibits secretion of other GI hormones
Note: is also secreted outside GI tract via hypothalamus and gamma cells of exocrine pancreas

Question 6

Histamine

Answer 6

Site of secretion: enterochromaffin-like (ECL) cells in gastric glands (target is parietal cells)
Stimuli of secretion:
Actions: stiulate acid production

Question 7

Ach

Answer 7

Source: cholinergic neurons
Actions: contraction of smooth muscle in wall, relaxation of sphincters, increase salivary secretion, increase gastric secretion, increase pacreatic secretion

Question 8

NE

Answer 8

Source: adrenergic neurons
Actions: relaxation of smooth muscle in wall, contraction of sphincters, increase salivary secretion

Question 9

Vasoactive intestinal peptide (VIP)

Answer 9

Source: neurons of ENS
Actions: relaxation of smooth muscle, increase intestinal secretion, increase pancreatic secretion

Question 10

NO

Answer 10

Source: neurons of ENS
Actions: relaxation of smooth muscle

Question 11

Gastrin-releasing peptide (GRP)

Answer 11

Source: vagal neurons of gastric mucosa
Actions: increase gastrin secretion

Question 12

Enkephalins

Answer 12

Source: neurons of ENS
Actions: contraction of smooth muscle, DECREASE in intestinal secretion

Question 13

Neuropeptide Y

Answer 13

Source: neurons of ENS
Actions: relaxation of smooth muscle, DECREASE in intestinal secretion

Question 14

Substance P

Answer 14

Source: co-secreted with ACh by neurons of ENS
Actions: contraction of smooth muscle, increase salivary secretion