gastric secretion

Question 1

what is the function of the fundus in the stomach ?

Answer 1

storage

Question 2

what is the function of the body of the stomach ?

Answer 2

storage
mucus
HCL
pepsinogen
intrinsic factor production

Question 3

what is the function of the antrum of the stomach ?

Answer 3

mixing/grinding
gastrin productio

Question 4

what cells in the gastric area secrete mucous ?

Answer 4

mucous neck cells

Question 5

what cells secrete pepsinogen ?

Answer 5

cheif cells (chief holds a can of pepsi)

Question 6

what do parietal cells of the stomach produce ?

Answer 6

Hcl and intrinsic factor

Question 7

how is gastric acid created ?

Answer 7

1- CO2 enters the parietal cell as a waste product
2- CO2 binds with H2O to produce HCO3 that is catalysed by carbonic anyhydrase
3- HCO3 immedietly dissociates to H+ and HCO3
4- H+ is transported out the cell at the HKATPase pump
5- HCO3 is exchanged for Cl- which then leaves at the apical membrane through a chloride channel
6- the osmotic gradient of the chlorine pulls water through tight junctions which combines with H+ and Cl- to create HCL gastric acid

Question 8

how does gastrin control gastric acid secretion ?

Answer 8

gastrin binds to CCKB receptor

this releases Ca+ which activates protein kinase C

PKC increase HK ATPase pump

Question 9

how does histamine control gastric acid secretion ?

Answer 9

binds to Gs H2 receptor which initiates adenyln cyclase to convert ATP - cAMP

cAMP then activates protein kinase A which increases HK ATPase pump activity

Question 10

how does ACh control gastric acid secretion ?

Answer 10

binds to M3 muscarinic cholinergic receptors which activate PKC to increase HK ATPase activity

Question 11

what is the cephalic phase of gastric acid secretion ?

Answer 11

sight smell, taste of food triggers the vagus nerve

vagus nerve stimulates Ach to increase parietal cell activity and also sitmulates G cells to produce gastrin and also increase parietal cell acitivty

presence of Gastrin/Ach activates ECL cells to produce histamine and increase parietal cell activity

Question 12

what triggers the gastric phase of gastric acid secretion ?

Answer 12

distension of stomach (arrival of food)

peptides in the lumen

Gastin/ACh

Question 13

how do we inhibit the cephalic phase in gastric acid secetion ?

Answer 13

stop eating

Question 14

how do we inhibit the gastric phase in gastric acid secretion ?

Answer 14

the decrease in pH from gastric acid causes a negative feedback and inhibits gastrin production

Question 15

describe the intestinal phase of inhibition of gastric acid secretion ?

Answer 15

acid in the duodenum triggers sphlancnic reflex and secretin release which decreases gastrin secretion and stimulation

fat/CHO in the duodenum stimulates the release of GIP which decrease gastric secretion and parietal HCl secretion

Question 16

what are enterogastrones ?

Answer 16

hormones (secretin, CCK,GIP) released from gland cells in the duodenal mucosa that prevent gastric acid build up by inhibiting acid secretion and reducing gastric emptying (contract pyloric sphincter)

Question 17

what pH converts pepsinogen to pepsin ?

Answer 17

pH <3 causes hydrolysis (inactive at a neutral pH)

Question 18

what are the roles of gastric mucous ?

Answer 18

protects mucosal surface from mechanical injury

neutral pH (HCO3) protects from gastric acid corrosion and pepsin digestion

Question 19

why is intrinsic factor important ?

Answer 19

binds with B12 and the complex is absorbed from the distal ileum to produce vitamin B12