Hormones and Neurotransmitters Of GI Tract

Question 1

gastrin

Answer 1

site of secretion- G cells of stomach

stimuli of secretion- small peptides, AA, distention of stomach, vagal stimulation via GRP

actions- increase gastric H+ secretion, stimulate growth of gastric mucosa

Question 2

CCK

Answer 2

site of secretion- I cells of duodenum and jejunum

stimuli of secretion- small peptides, AA, fatty acids

actions- increase pancreatic enzyme secretion, increase pancreatic HCO3 secretion, stimulates contraction of the gallbladder and relaxation of the sphincter of Oddi, stimulates growth of the exocrine pancreas and gallbladder, inhibits gastric emptying

Question 3

Secretin

Answer 3

site of secretion- S cells of the duodenum

stimuli of secretion- H+ in the duodenum, fatty acids in the duodenum

actions- increase pancreatic HCO3 secretion, increase biliary HCO3 secretion, decrease gastric H+ secretion, inhibits trophic effect of gastrin on the gastric mucosa

Question 4

Glucose-dependent insulinotropic peptide (GIP)

Answer 4

site of secretion- duodenum and jejunum

stimuli of secretion- fatty acids, AA, oral glucose

actions- increases insulin secretion from pancreatic beta cells, decreases gastric H+ secretion

Question 5

acetylcholine (ACh)

Answer 5

source- cholinergic neurons

actions- contraction of smooth muscle in wall, relaxation of sphincters, increase salivary secretion, increase gastric secretion, increase pancreatic secretion

Question 6

Norepinephrine (NE)

Answer 6

source- adrenergic neurons

actions- relaxation of smooth muscle in wall, contraction of sphincters, increases salivary secretion

Question 7

Vasoactive intestinal peptide (VIP)

Answer 7

source- neurons of the ENS

actions- relaxation of smooth muscle, increase intestinal secretion, increase pancreatic secretion

Question 8

Nitric Oxide (NO)

Answer 8

source- neurons of ENS

actions- relaxation of smooth muscle

Question 9

gastrin-releasing peptide (GRP)

Answer 9

source- vagal neurons of gastric mucosa

actions- increase gastrin secretion

Question 10

Enkephalins

Answer 10

source- neurons of ENS

actions- contraction of smooth muscle, decreases intestinal secretion

Question 11

Neuropeptide Y

Answer 11

source- neurons of ENS

actions- decrease intestinal secretion

Question 12

substance P

Answer 12

source- co-secreted with ACh by neurons in the ENS

actions- contraction of smooth muscle, increases salivary secretion