Physiology- Hormones, Peptides and Neurotransmitters

Question 1

Gastrin: What cells secrete it? Where are they located? What stimulates/inhibits its secretion? What are its actions?

Answer 1

G cells in antrum (stomach) and duodenum.
Stimuli: luminal Aa, peptides, vagal, distension
Inhibitors: high H+
Action: increase gastric emptying, increase acid (HCl) via stimulation of parietal cells

Question 2

Secretin: What cells secrete it? Where are they located? What stimulates/inhibits its secretion? What are its actions?

Answer 2

S cells of duodenum.
Stimuli: high luminal H+, pH < 4.5
Inhibitors: increased pH
Action: Neutralizing acid (stimulating pancreatic and bile HCO3- secretion), inhibiting gastric acid secretion inhibiting gastric emptying
Stimuli: luminal H+, pH < 4.5
Inhibitor: increased pH

Question 3

Motilin: What cells secrete it? Where are they located? What stimulates/inhibits its secretion? What are its actions?

Answer 3

Source: duodenum, jejunum
Action: stimulates gastric and intestinal motility
Stimuli: cyclic neural stimulation during fasting, fatty acids and acids in the duodenum

Question 4

Peptide YY: What cells secrete it? Where are they located? What stimulates/inhibits its secretion? What are its actions?

Answer 4

Source: intestine L cells
Stimuli: FFA, glucose, hydrolyzed protein
Action: inhibition gastric emptying, pancreatic secretion, gastric acid, motility

Question 5

CCK: What cells secrete it? Where are they located? What stimulates/inhibits its secretion? What are its actions?

Answer 5

Source: duodenum, jejunum, illeum (I cells)
Stimuli: free fatty acids, aa
Action: pancreatic secretion (enzymes and HCO3 secretion), gallbladder contraction and sphincter of Oddi relaxation, gastric emptying inhibition.

Question 6

GIP: What cells secrete it? Where are they located? What stimulates/inhibits its secretion? What are its actions?

Answer 6

Source: duodenum, jejunum (K cells)
Stimuli: Glucose, amino acids, fatty acids
Inhibitor: insulin secretion, inhibits gastric acid secretion, inhibits gastric emptying.

Question 7

Ghrelin: What cells secrete it? Where are they located? What are its actions?

Answer 7

Source: O/X gastric cells
Increases food intake
Increases intestinal motility
Stimulates GH secretion