GI regulatory substances

Question 1

Cholecystokinin: Source?

Answer 1

I cells (duodenum, jejunum)

Question 2

CCK: Action?

Answer 2

Increases pancreatic secretion (via muscarinic pathways)
Increases gallbladder contraction
Decreases gastric emptying
Increases sphincter of Oddi relaxation

Question 3

CCK: Regulation?

Answer 3

Increased by fatty acids, amino acids

Question 4

Gastrin: Source?

Answer 4

G cells (antrum of stomach)

Question 5

Gastrin: Action?

Answer 5

Increases gastric H+ secretion
Increases growth of gastric mucosa
Increases gastric motility

Question 6

Gastrin: Regulation?

Answer 6

Increased by stomach distension/alkalinization, amino acids, peptides, vagal stimulation
Decreased by stomach pH < 1.5

Question 7

Zollinger-Ellison Syndrome results in an increase in which GI regulatory substance?

Answer 7

Gastrin

Question 8

Chronic Proton Pump Inhibitor use can cause an Increase in what GI regulatory substance?

Answer 8

Gastrin

Question 9

What 2 amino acids are potent stimulators of Gastrin?

Answer 9

Phenylalanine and tryptophan

Question 10

Glucose-dependent insulinotropic peptide: Source?

Answer 10

K cells (duodenum, jejunum)

Question 11

Glucose-dependent insulinotropic peptide: Action?

Answer 11

Exocrine: Decreases gastric H+ secretion
Endocrine: Increases insulin release

Question 12

Glucose-dependent insulinotropic peptide: Regulation?

Answer 12

Increased by fatty acids, amino acids, oral glucose

Question 13

Also known as GIP (Gastric Inhibitory Peptide):

Answer 13

Glucose-dependent insulinotropic peptide

Question 14

Oral glucose load is used more rapidly than the equivalent given by IV due to secretion of what?

Answer 14

GIP

Question 15

Motilin: Source?

Answer 15

Small Intestine

Question 16

Motilin: Action?

Answer 16

Produces migrating motor complexes (MMCs)

Question 17

Motilin: Regulation?

Answer 17

Increased in fasting state

Question 18

Example of a motilin receptor agonist and action

Answer 18

Erythromycin

Used to stimulate intestinal peristalsis

Question 19

Secretin: Source?

Answer 19

S cells (duodenum)

Question 20

Secretin: Action?

Answer 20

Increases pancreatic HCO3- secretion
Decreases gastric acid secretion
Increases bile secretion

Question 21

Secretin: Regulation?

Answer 21

Increased by acid, fatty acids in lumen of duodenum

Question 22

Purpose of Increased HCO3- by Secretin?

Answer 22

Neutralizes gastric acid in duodenum, allowing pancreatic enzymes to function

Question 23

Somatostatin: Source?

Answer 23

D cells (pancreatic islets, GI mucosa)

Question 24

Somatostatin: Action?

Answer 24

Decreases gastric acid and pepsinogen secretion
Decreases pancreatic and small intestine fluid secretion
Decreases gallbladder contraction
Decreases insulin and glucagon release

Question 25

Somatostatin: Regulation?

Answer 25

Increased by acid

Decreased by vagal stimulation

Question 26

What inhibits GH, insulin, and other hormones?

Answer 26

Somatostatin

Question 27

What inhibits digestion and absorption of substances needed for growth?

Answer 27

Somatostatin

Question 28

Analog for Somatostatin used to treat acromegaly, insulinoma, carcinoid syndrome, and variceal bleeding:

Answer 28

Octreotide

Question 29

Octreotide is an analog of what? And is used to treat what conditions?

Answer 29

Somatostatin

Used to treat acromegaly, insulinoma, carcinoid syndrome, variceal bleeding

Question 30

Nitric Oxide: Action?

Answer 30

Increases smooth muscle relaxation, including Lower Esophageal Sphincter (LES)

Question 31

What is achalasia, and what is implicated in its cause?

Answer 31

Increased LES tone

Loss of NO secretion

Question 32

Vasoactive intestinal polypeptide (VIP): Source?

Answer 32

Parasympathetic ganglia in sphincters, gallbladder, and small intestine

Question 33

VIP: Action?

Answer 33

Increases intestinal water and electrolyte secretion

Increases relation of intestinal smooth muscle and sphincters

Question 34

VIP: Regulation?

Answer 34

Increased by distention and vagal stimulation

Decreased by adrenergic input

Question 35

What is a VIPoma?

Answer 35

Pancreatic tumor that secretes VIP (non-alpha, non-beta)

copious Watery Diarrhea, Hypokalemia, and Achlorhydria (WDHA syndrome)

Question 36

What is WDHA syndrome?

Answer 36

Causes copious Watery Diarrhea, Hypokalemia, and Achlorhydria
Caused by VIPoma (pancreatic tumor that secretes VIP)

Question 37

Intrinsic Factor: Source?

Answer 37

Parietal cells (stomach)

Question 38

Intrinsic Factor: Action?

Answer 38

Vitamin B12-binding protein (required for B12 uptake in terminal ileum)

Question 39

Autoimmune destruction of parietal cells leads to:

Answer 39

Chronic gastritis and pernicious anemia (no IF for B12 uptake)

Question 40

Gastric Acid: Source?

Answer 40

Parietal cells (stomach)

Question 41

Gastric Acid: Action?

Answer 41

Decreases stomach pH

Question 42

Gastric Acid: Regulation?

Answer 42

Increased by histamine, ACh, gastrin

Decreased by somatostatin, GIP, prostaglandin, secretin

Question 43

What is a Gastrinoma?

Answer 43

Gastrin-secreting tumor that causes high levels of acid secretion and ulcers refractory to medical therapy.

Question 44

Pepsin: source?

Answer 44

Chief cells (stomach)

Question 45

Pepsin: action?

Answer 45

Protein digestion

Question 46

Pepsin: Regulation?

Answer 46

Increased by vagal stimulation, local acid

Question 47

What converts pepsinogen to pepsin?

Answer 47

H+

Question 48

HCO3- : source?

Answer 48

Mucosal cells (stomach, duodenum, salivary glands, pancreas)
Brunner glands (duodenum)

Question 49

HCO3- : action?

Answer 49

Neutralizes acid

Question 50

HCO3- : Regulation?

Answer 50

Increased by pancreatic and biliary secretion with Secretin

Question 51

Where is HCO3- in the stomach?

Answer 51

Trapped in mucus that covers the gastric epithelium.

Question 52

How does Gastrin increase acid secretion?

Answer 52

Through its effects on enterochromaffin-like (ECL) cells, which leads to histamine release. Histamine stimulates parietal cells to increase acid.