GI regulatory substances

Question 1

Where is gastrin secreted from?

Answer 1

G cells in the antrum of the stomach and duodenum

Question 2

What is the action of gastrin?

Answer 2

Inc gastric H+ secretion, incr growth of gastric mucosa, Inc gastric motility

Question 3

What stimulates gastrin secretion?

Answer 3

Stomach distention, alkalinization, amino acids, peptides, vagal stimulation

Question 4

What inhibits gastrin secretion?

Answer 4

pH < 1.5

Question 5

What is the effect of chronic PPI use on gastrin secretion?

Answer 5

Increases

Question 6

Where is somatostatin secreted from in the GI system?

Answer 6

D cells of pancreas, GI mucosa

Question 7

What are the actions of somatostatin in the GI system?

Answer 7

1. Decr gastric acid and pepsinogen secretion
2. Decr pancreatic and small intestine fluid secretion
3. Decr gallbladder contraction
4. Decr insulin and glucagon release
   - Generally, decreases digestive activity.

Question 8

What stimulates somatostatin release?

Answer 8

Acid

Question 9

What inhibits somatostatin release?

Answer 9

Vagal stimulation

Question 10

What medication is an analogue for somatostatin?

Answer 10

Octreotide

Question 11

What is the effect of somatostatin on GH release?

Answer 11

Inhibits GH

Question 12

Where is cholecystokinin released from?

Answer 12

I cells (of the duodenum and jejunum)

Question 13

What are the effects of CCK?

Answer 13

1. Incr GB contraction
2. Incr Pancr secretion
3. Decr gastric emptying
4. Incr sphincter of oddi relaxation

Question 14

What stimulates CCK release?

Answer 14

Fatty acids, amino acids

Question 15

What pathways does CCK act on to cause pancreatic secretion?

Answer 15

Neural muscarinic pathways

Question 16

Where is secretin released from?

Answer 16

S cells of the duodenum

Question 17

What are the actions of secretin?

Answer 17

1. Increase pancreatic bicarb secretion
2. Decrease gastric acid secretion
3. Increase bile secretion

Question 18

What stimulates secretin release?

Answer 18

Acid, fatty acids in lumen of duodenum

Question 19

What is the purpose of HCO3- secretion?

Answer 19

neutralizes gastric acid in duodenum, allowing pancreatic enzymes to function

Question 20

From where is GIP (glucose-dependent insulinotropic peptide) secreted?

Answer 20

K cells of duodenum, jejunum

Question 21

What is the exocrine function of GIP?

Answer 21

Decrease gastric H+ secretion

Question 22

What is the endocrine function of GIP?

Answer 22

Incr insulin release

Question 23

What stimulates GIP release?

Answer 23

Incr in fatty acids, amino acids, oral glucose

Question 24

Why are different quantities of insulin released in response to glucose PO vs IV?

Answer 24

GIP is released with PO glucose, but not IV.

Question 25

Where is motilin released from?

Answer 25

Small intestine M cells (esp duod & jej)

Question 26

What is the function of motilin?

Answer 26

Produces migrating motor complexes

Question 27

What are migrating motor complexes?

Answer 27

Peristalsis of the gut that occurs during interdigestive phases, to clear out indigestive substances on for excretion

Question 28

When is motilin released?

Answer 28

During fasting state

Question 29

How does erythromycin work to stimulate intestinal peristalsis?

Answer 29

It is a motilin receptor agonist

Question 30

Were is vasoactive intestinal polypeptide released from?

Answer 30

Parasympathetic ganglia in sphincters, GB, and small intestine

Question 31

What is the function of VIP?

Answer 31

Incr intestinal water and electrolyte secretion | Incr relaxation of intestinal smooth muscle and sphincters

Question 32

What stimulates VIP secretion?

Answer 32

Incr by distension and vagal stimulation

Question 33

What inhibits VIP secretion?

Answer 33

Decr by adrenergic input

Question 34

What are the symptoms of VIPoma?

Answer 34

islet cell pancreatic tumor that secretes VIP - Watery Diarrhea, Hypokalemia, and Achlorhydria

Question 35

Loss of what is implicated in achalasia?

Answer 35

NO, causing increased LES tone. (NO increases smooth muscle relaxation)