Gastric Secretion

Question 1

At what part of the stomach does the main storage concentrate?

Answer 1

Fundus

Question 2

What is the function of the body part of the stomach?

Answer 2

Storage
Mucous
HCL production
Pepsinogen 
Intrinsic factor production

Question 3

What part in the stomach is gastrin produced?

Answer 3

The pylorus antrum

Question 4

How does the stomach prevent it digesting itself?

Answer 4

It binds pepsin to the inactive precursor pepsinogen

Question 5

What is pepsin?

Answer 5

A proteolytic enzyme

Question 6

What is gastrin produced from?

Answer 6

Specialised endocrine cells- G cells

Question 7

What type of cells produce pepsinogens?

Answer 7

Cheif cells

Question 8

What does parietal cells secrete?

Answer 8

HCL

intrinsic factor

Question 9

What is the function of intrinsic factor and where is it produced?

Answer 9

Intrinsic factor is reauired for the absorption of vitamin B12
It is peoduced from parietal cells in the gastric glands

Question 10

What enzyme converts co2 and water to H2CO3?

Answer 10

Carbonic anhydrase

Question 11

In the cell, H2CO3 is beoken down into H and what ?

Answer 11

hCO3

Question 12

When HCO3 leaves the cell, what enters the same time?

Answer 12

Chlorine (Cl)

Question 13

what are the 3 different mechanisms of control of gastric secretion?

Answer 13

neurocrine - vase /reflexes
endocrine = gastrin
paracrine = histamine

Question 14

what 3 phases are involved in inhibition of gastric secretion?

Answer 14

cephalic phase - stop chewing = decrease in vagus nerve
gastric = decrease in PH = decrease in gastrin
intestinal - acid in duodenum releases Secretin and activates enterogastric (splanchnic reflexes)
& fat in duodenum releases GIP

Question 15

what are enterogastrones and name a few.

Answer 15

enterogastrones are hormones which inhibit gastrin production
i.e. prostaglandins, cholecystokinin CCK, GIP

Question 16

where are enterogastrones released from?

Answer 16

gland cells in the duodenal mucosa

Question 17

where is gastric mucous produced from?

Answer 17

epithelial cells and mucous neck cells

Question 18

what is the main role of gastric mucous?

Answer 18

cytoprotective role and neutralises the PH

Question 19

where is intrinsic factor secreted and where is it absorbed?

Answer 19

secreted from parietal cells

absorbed from ileum

Question 20

what does stimulation of the vagus nerve do in terms of gastric production?

Answer 20

activates ACh which stimulates parietal cells

activates G cells which produces gastrin which activates parietal cells

Question 21

what happens when gastrin/ACh stimulate ECL cells?

Answer 21

it causes histamine to be released from the ECL cells which stimulate parietal cells

Question 22

how does fat in the duodenum inhibit gastric secretion?

Answer 22

fat in the duodenum causes GIP release which decreases gastric secretion and parietal HCL secretion

Question 23

how does histamine increase gastric secretion?

Answer 23

histamine binds to its receptor which activates Gs.
This protein converts ATP to cAMP which in turn activates the K/H ATPase.
this releases H out of the cell = decrease in PH

Question 24

what converts inactive trypsinogen to active trypsin?

Answer 24

enterokinase

Question 25

where is bicarbonate released from?

Answer 25

brunner gland duct cells