Ward: Gastric physio of digestion (cont'd) Flashcards Preview

Block 3 Week 3 Meg > Ward: Gastric physio of digestion (cont'd) > Flashcards

Flashcards in Ward: Gastric physio of digestion (cont'd) Deck (31)
Loading flashcards...
1

Regulation of gastric secretion occurs via two main ways

1. neural pathway
2. hormonal pathway

2

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

vagal

3

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

histamine
gastrin

4

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

ACh

5

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

gastrin; histamine

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.

Cephalic phase

7

What portion of gastric secretion is associated with the cephalic phase

20-30%

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

Gastric phase

9

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

60%

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

Intestinal phase

11

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

10%

12

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

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

13

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

secretin
CCK
somatostatin

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

somatostatin

15

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


acidsomatostatin

16

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

acid
secretin
nervous reflex

17

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

fatty acids
GIP

18

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

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

19

proteolytic enzyme active at low pH (~2)

pepsin

20

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

Ca+

21

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

Ca+

22

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

cAMP

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).

vagal and local stimulation; histamine and HCl

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.

Intrinsic factor; pernicious anemia

25

Released from dietary protein by gastric acid and pepsin

B12

26

What do mucous neck cells secrete?

mucus
bicarbonate

27

What do parietal cells secrete?

HCl (gastric acid)
intrinsic factor

28

What do enterochromaffin-like cells secrete?

histamine

29

What do chief cells secrete?

pepsin
gastric lipase

30

What do D cells secrete?

somatostatin