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Surgical Recall > GI Hormones & Physiology > Flashcards

Flashcards in GI Hormones & Physiology Deck (43):
1

What do gastric parietal cells produce?

HCl, intrinsic factor

2

What do chief cells produce?

Pepsinogen

3

What do G cells produce?

Gastrin

4

What do mucous neck cells produce?

Bicarbonate mucus

5

What is pepsin?

Proteolytic enzyme that hydrolyzes peptide bonds

6

What is intrinsic factor?

Protein secreted by the parietal cells that combines with vitamin B12 and enables absorption in the terminal ileum

7

What 3 substances stimulate HCl release by parietal cells?

1. Histamine
2. Acetylcholine
3. Gastrin

8

What is the enterohepatic circulation?

Circulation of bile acids from the liver to the gut and back to the liver via the portal vein

9

Where are most of the bile acids absorbed?

Terminal ileum

10

How many times is the entire bile acid pool circulated during a typical meal?

Twice

11

What are the stimulators of gallbladder emptying?

Cholecystokinin, vagal input

12

What are the inhibitors of gallbladder emptying?

Somatostatin, sympathetics, vasoactive intestinal peptide (VIP)

13

What is the source of cholecystokinin?

Duodenal mucosal cells

14

What stimulates the release of cholecystokinin?

Fat, protein, amino acids, HCl

15

What inhibits the release of cholecystokinin?

Trypsin, chymotrypsin

16

What are the actions of cholecystokinin?

1. Empties gallbladder
2. Opens ampulla of Vater
3. Slows gastric emptying
4. Stimulates pancreatic acinar cell growth and release of exocrine products

17

What is the source of secretin?

Duodenal cells (argyrophilic S cells)

18

What stimulates the release of secretin?

pH < 4.5, fat in the duodenum

19

What inhibits the release of secretin?

High pH in duodenum

20

What are the actions of secretin?

1. Releases pancreatic bicarbonate, enzymes, and water
2. Releases bile and bicarbonate
3. Decreases LES tone
4. Decreases release of gastric acid

21

What is the source of gastrin?

G cells

22

What stimulates the release of gastrin?

1. Stomach peptides and amino acids
2. Vagal input
3. Calcium

23

What inhibits the release of gastrin?

pH < 3.0, stomatostatin

24

What are the actions of gastrin?

Release of HCl from parietal cells; trophic effects on mucosa of the stomach and small intestine

25

What is the source of somatostatin?

Pancreatic D cells

26

What stimulates the release of somatostatin?

Food

27

What are the actions of somatostatin?

Globally inhibits GI function

28

What is the purpose of the colon?

Reabsorption of water and storage of stool

29

What is the main small bowel nutritional source?

Glutamine

30

What is the main nutritional source of the colon?

Butyrate (SCFA)

31

Where is calcium absorbed in the GI tract?

Duodenum actively, jejunum passively

32

Where is iron absorbed in the GI tract?

Duodenum

33

Which hormone primarily controls gallbladder contraction?

CCK

34

What supplement does a patient need after removal of the terminal ileum or stomach?

Vitamin B12

35

What are the main constituents of bile?

Water, phospholipids, bile acids, cholesterol, bilirubin

36

What are most gallstones made of?

Cholesterol

37

How do opiates affect the bowel?

By stimulating sodium absorption and inhibiting secretion in the ileum as well as decreasing GI motility by incoordinated peristalsis (therefore, place patients on stool softeners)

38

Which electrolytes does the colon actively absorb?

Na, Cl

39

Which electrolytes does the colon actively secrete?

Bicarbonate (plays a role in diarrhea causing the patient to have a normal anion gap acidosis)

40

Which electrolytes does the colon passively secrete?

K

41

What is the gastrocolic reflex?

Increased secretory and motor functions of the stomach result in increased colonic motility

42

What is the blood supply to the liver?

75% from portal vein
25% from hepatic artery

43

What are Peyer patches?

Nodules of lymphoid tissue with B and T cells in the small intestine that selectively sample luminal antigens found in the terminal ileum