Ward: Gastric physio of digestion (cont'd)

Question 1

Regulation of gastric secretion occurs via two main ways

Answer 1

1. neural pathway

2. hormonal pathway

Question 2

The neural pathway of gastric stimulation relies on (blank) nerve stimulation

Answer 2

vagal

Question 3

The hormonal pathway of gastric stimulation relies on these two hormonal effectors

Answer 3

histamine

gastrin

Question 4

(blank) stimulates secretion of a wide range of substances including pepsinogen, HCl, mucus, and gastrin

Answer 4

ACh

Question 5

(blank) and (blank) strongly stimulate the release of HCl by parietal cells.

Answer 5

gastrin; histamine

Question 6

The first phase of gastric secretion. Occurs before food enters the stomach. Stimulated by the senses. Stimulus originates in the cerebral cortex or amygdala/hypothalamus and reaches the stomach via the vagus.

Answer 6

Cephalic phase

Question 7

What portion of gastric secretion is associated with the cephalic phase

Answer 7

20-30%

Question 8

The second phase of gastric secretion. Gastric distension and partially digested proteins stimulate mechano-receptors which stimulate paretial cells through short local enteric reflexes and long vagovagal reflexes

Answer 8

Gastric phase

Question 9

What portion of gastric secretion is associated with the gastric phase?

Answer 9

60%

Question 10

The presence of proteins in the duodenum can cause the release of small amounts of gastric juices possibly through release of gastrin. Distension of the intestine also causes acid secretion possibly through the release of enterooxyntin, a hormone from endocrine cells. Several inhibitory factors released by the intestine can override the minor excitatory effects of gastrin

Answer 10

Intestinal phase

Question 11

What portion of gastric secretion is associated with the intestinal phase?

Answer 11

10%

Question 12

Things that can result in a decrease in secretion from the enteric nervous system and vagal nerves

Answer 12

distension
acid in upper intestine
protein breakdown products
irritation of the mucosa

Question 13

Intestinal hormones released as a result of acid, fat protein breakdown products, hyper-hypo osmotic fluids

Answer 13

secretin
CCK
somatostatin

Question 14

When the pH of the stomach decreases below 3, the endocrine cells in the antrum secrete (blank) that inhibits the release of gastrin and gastric secretion

Answer 14

somatostatin

Question 15

In the antrum, what stimulus inhibits gastrin release and acid secretion? What mediator inhibits gastrin release and acid secretion?

Answer 15

acidsomatostatin

Question 16

In the duodenum, what stimulus inhibits gastrin release and acid secretion? What mediators inhibit gastrin release and acid secretion?

Answer 16

acid
secretin
nervous reflex

Question 17

In the duodenum and jejunum, what stimulus inhibits gastrin release and acid secretion? What mediator inhibits gastrin and acid secretion?

Answer 17

fatty acids

GIP

Question 18

What cell types secrete pepsinogen? Is it active or inactive when secreted? How is it activated?

Answer 18

mucous, chief cell
inactive
comes in contact with HCl to become activated

Question 19

proteolytic enzyme active at low pH (~2)

Answer 19

pepsin

Question 20

ACh causes an influx of (blank) into the oxyntic cell, resulting in acid secretion.

Answer 20

Ca+

Question 21

Gastrin binding to its receptor also causes influx of (blank)

Answer 21

Ca+

Question 22

Histamine does not require extracellular Ca+ for stimulation of acid secretion. What is the intracellular messenger that couples histamine to H+ secretion?

Answer 22

cAMP

Question 23

What causes the release of gastrin from pyloric glands? Gastrin is carried in the blood stream and stimulates the release of (blank) and (blank).

Answer 23

vagal and local stimulation; histamine and HCl

Question 24

glycoprotein secreted by parietal cells: It is essential for the absorption of vitamin B12 in the ileum. Failure to secrete this can lead to this condition.

Answer 24

Intrinsic factor; pernicious anemia

Question 25

Released from dietary protein by gastric acid and pepsin

Answer 25

B12

Question 26

What do mucous neck cells secrete?

Answer 26

mucus

bicarbonate

Question 27

What do parietal cells secrete?

Answer 27

HCl (gastric acid)

intrinsic factor

Question 28

What do enterochromaffin-like cells secrete?

Answer 28

histamine

Question 29

What do chief cells secrete?

Answer 29

pepsin

gastric lipase

Question 30

What do D cells secrete?

Answer 30

somatostatin

Question 31

What do G cells secrete?

Answer 31

gastrin