Chapter 42

Question 1

The mucosa consists of these 2 things:

Answer 1

Surface epithelial cells and glands

Question 2

With increasing rates of gastric juice secretion, [H+] concentration _____, and [Na+] concentration _____.

Answer 2

H+ increases, Na+ decreases

Question 3

The proximal portion of the stomach secretes:

Answer 3

Acid, pepsinogens, intrinsic factor, bicarbonate, and mucus

Question 4

The distal portion of the stomach secretes:

Answer 4

Gastrin and somatostatin

Question 5

What are the 2 anatomical sections of the stomach?

Answer 5

Corpus and the antrum

Question 6

What is the function of the stomach?

Answer 6

The stomach accomodates food, mixes it with gastric secretions, grinds it, and empties the food (now called chyme) into the duodenum.

Question 7

What specialized structure does the parietal cell have?

Answer 7

Specialized tubulovesicular structure

Question 8

What happens when the parietal cell is stimulated/activated?

Answer 8

It secretes acid

Question 9

What channel/pump is responsible for the secretion of acid by parietal cells?

Answer 9

The H+/K+ pump

Question 10

What three chemical signals (secretogogues) stimulate acid secretion from parietal cells?

Answer 10

1. Acetylcholine
2. Gastrin
3. Histamine

Question 11

How do the 3 secretogogues act physiologically on the parietal cell?

Answer 11

Either through the Ca2+ - Diacylglycerol (DAG) pathway or cAMP

Question 12

What 2 cells secrete gastrin?

Answer 12

Antral and duodenal G-cells

Question 13

Histamine is secreted by what specific cells in the stomach?

Answer 13

Enterochromaffin-like cells in the corpus section of the stomach

Question 14

Somatostatin is secreted by which cells?

Answer 14

Gastric D-cells

Question 15

What is the role of somatostatin?

Answer 15

Inhibits acid secretion

Question 16

What other chemical signals aside from somatostatin inhibit acid secretion?

Answer 16

Several enteric hormones (enterogastrones) and prostaglandins

Question 17

What are the 3 phases of acid secretion that is stimulated by a meal?

Answer 17

Basal state (no meal)
Meal-stimulated phases:
1. Cephalic phase
2. Gastric phase
3. Intestinal phase

Question 18

What 2 intramolecular pathways activate chief cells?

Answer 18

cAMP and Ca2+ pathways

Question 19

What is the role of chief cells?

Answer 19

To secrete pepsinogens, which are the precursors to protein digestion

Question 20

What is required for pepsinogen activation and pepsin activity?

Answer 20

Low pH

Question 21

What does vagal innervation and irritation stimulate?

Answer 21

Stimulates gastric mucous cells to secrete mucin

Question 22

What is mucin?

Answer 22

A glycoprotein that is part of the mucosal barrier

Question 23

What do gastric surface cells secrete?

Answer 23

HCO3-

Question 24

What chemical signals stimulates gastric surface cells?

Answer 24

Acetylcholine, acids, and prostaglandins

Question 25

How does mucus protect the gastric surface epithelium?

Answer 25

By trapping an HCO3- -rich fluid near the apical border of these cells

Question 26

Entry of acid into the duodenum induces what reaction?

Answer 26

The release of secretin from S cells

Question 27

The release of secretin from S cells in the duodenum does what?

Answer 27

Stimulates the pancreas and the duodenum to secrete bicarbonate to neutralize the acid entering from the stomach into the duodenum

Question 28

Gastric motor activity plays what roles?

Answer 28

Filling, churning, and emptying the stomach of food

Question 29

Filling of the stomach is facilitated by what 2 concepts?

Answer 29

Receptive relaxation of the stomach and gastric accomodation (to the food)

Question 30

The stomach churns the food up until what point?

Answer 30

Until the food particles are small enough to be gradually emptied into the duodenum