Gastric function

Question 1

what are the 3 main stomach functions

Answer 1

Temporary food store
Mediate some degradation of protein and starch
Releases HCL to kill bacteria and activate pepsin

Question 2

What is tonic contraction

Answer 2

When the contraction in the stomach is maintained despite it being empty

Question 3

What happens to the stomach muscles when an animal eats

Answer 3

they relax = receptive relaxation
Regulated via vagal fibres
Allows for an increase in stomach content without an increase in pressure

Question 4

What happens in the distal stomach

Answer 4

Active digestion as it has stronger peristaltic contractions
Large part of pylorus wall contracts simultaneously to increase luminal pressure and force chyme through partially open sphincter

Question 5

What are the cell types in the stomach

Answer 5

Mucin producing cells
parietal cells
ECL cells
chief cells
endocrine cells

Question 6

What do parietal cells do in the stomach

Answer 6

Produce HCL and intrinsic factor

Question 7

What do chief cells do in the stomach

Answer 7

Produce pepsinogen

Question 8

What do endocrine cells do in the stomach

Answer 8

G cells - secrete gastrin
ECL - histamine

Question 9

What do the glands in the cardia secrete

Answer 9

Mucus

Question 10

Where is most of the gastric juice produced

Answer 10

Fundus and corpus
consists mainly of HCL and pepsinogen

Question 11

What is the function of HCl in the stomach

Answer 11

Degrades connective tissue, muscle and micro-organisms
Transforms pepsinogen into pepsin

Question 12

What is HCL produced by

Answer 12

Parietal cells with a H/K ATP-ase pump for the H+ and HCO3-/Cl- pump for Cl-

Question 13

What is pepsinogen

Answer 13

The inactive form of pepsin produced by chief cells

Question 14

How are gastric secretions regulated

Answer 14

Gastrin released in the blood to stimulate secretion of HCl, pepsinogen and to promote gastric motility
Histamine stimulates HCl secretion

Question 15

What inhibits secretion

Answer 15

low pH causes somatostatin release to block gastrin release
HCl is low but H+ is high at the start of a meal to prevent acid secretion
H+ conc decreased by buffer solution when animal eats - releases gastrin

Question 16

How are nutrients degraded

Answer 16

Recently swallowed food found in proximal stomach
Contractions here are weak so food layers in order of consumption -> enzymes can act before becoming deactivated

Question 17

What factors effect gastric emptying

Answer 17

Expansion of stomach wall
Gastrin
Distension of duodenum
High fat and protein conc
Reduced pH

Question 18

How does expansion of the stomach wall effect gastric emptying

Answer 18

Initiates short reflexes om stomach wall and long reflexes via vagus nerve transmission
ACH secreted to increase contractions
volume of gastric content = strength of contraction and emptying rate

Question 19

How does gastrin effect gastric regulation

Answer 19

Stimulates contractions and relaxes pyloric sphincter
Increases gastric juice secretions
Increases breakdown of food and transit to small intestine

Question 20

How does distension of duodenum affect gastric emptying

Answer 20

As duodenum fills, the pyloric sphincter closes to slow down the transfer of chyme

Question 21

What are the important mediators in gastric emptying

Answer 21

GIP
Secretin
CCK