Physiology

Question 1

Gastrin

Answer 1

Location: G cells (antrum)

Stimulation: food, pH change, other transmitters, vagus nerve
Inhibited by: dec pH, somatostatin

Mechanism: produced as prehormone, secretory granules in golgi apparatus

Target: parietal cells, D cells

Function: major hormonal control of gastric H+ secretion, inc HCl, inc pepsinogen, inc intrinsic factor, inc gastric motility, stimulates parietal cell maturation

Question 2

Cholecystokinine

Answer 2

Location: I cells (intestine - upper small)

Simulation: food, pH change, other transmitters

Mechanism: produced as prehormone, secretory granules in golgi apparatus

Function: regulation of pancreatic enzyme secretion, induces satiety, dec gastric emptying, inc pancreatic enzyme secretion, gallbladder contraction, relaxation of sphincter of Oddi

Question 3

Somatostatin

Answer 3

Location: D cells (gastric) - pancreas and stomach

Function: paracrine regulator of H+ and gastrin

Question 4

Vasoactive intestinal peptide

Answer 4

= VIP

Location: myenteric inhibitory motor neurons/submucosal neurons

Function: neural inhibition of motility/stimulation of fluid secretion

Question 5

Secretin

Answer 5

Location: S cells (intestine)

Function: regulation of pancreatic HCO3

Question 6

Cellular communication

Answer 6

Paracrine: somatostatin

Endocrine: insulin, gastrin

Autocrine: IGF, NO

Neurocrine: Ach, VIP

Question 7

Nervous system

Answer 7

PSNS - vagus

SNS - splanchnic

Enteric - intrinsic to gut wall (myenteric plexus, peristalsis controlled by “pacemaker cells” - interstitial cells of Cajal)