gastric secretion

Question 1

function of stomach fundus

Answer 1

storage

Question 2

function of stomach body

Answer 2

storage 
mucus 
HCl
pepsinogen 
intrinsic factor

Question 3

antrum

Answer 3

mixing/grinding

gastrin

Question 4

what do cheif cells make

Answer 4

pepsinogens

Question 5

what do parietal cells make

Answer 5

HCl

intrinsic factor

Question 6

how is HCl made

Answer 6

CO2 combines w water in cytoplasm (carbonic anydrase) to make carbonic acid
dissociates to H+ and bicarbonate
H+ pumped out cell duye to conc gradient
bicarbonate pumped out in exchange for Cl-
Cl- pumped into stomach lumen
Cl- and H+ combine

Question 7

gastric acid secretion is controlled by three mechanisms….

Answer 7

neurocine (vagus/local relfexes)
endocrine (gastrin)
paracrine (histamine)

Question 8

Gastric acid secretion - cephalic phase

Answer 8

sight/smell/taste food –> vagus nerve –> more Ach to paritel cells
or vagus nerve –> G cells –> more gastrin to parietal cells

or
gastrin/Acl –> ECL cells –> huistamine to parietal cells

Question 9

Gastric acid secretion - gastric phase

Answer 9

distension stomach –>vagal reflex –> Ach –> pariteal cells

peptides in lumen –> G cells –> gastrin –> parietal cells

gastrin/Ach –> ECL cells –> histamine –> parietal cells

Question 10

mechanisms inhibiting gastric acid secretion: cephalic phase

Answer 10

stopping eating –> decreased vagal activity

Question 11

mechanisms inhibiting gastric acid secretion: gastric phase

Answer 11

decrease pH (more HCl) –> less gastrin

Question 12

mechanisms inhibiting gastric acid secretion: intestinal phase

Answer 12

acid in duodenum –> enterogastirc reflex and secretin release –> decrease gastrin release –> less gastrin stimulation of parietal cells

fat/CHO in duodenum –> GIP release –> less gastrin secretion

Question 13

enterogastrones

Answer 13

hormones released from gland cells in duodneal mucosa

secretin, CCK, GIP

Question 14

enterogastrones: what are they released in response to

Answer 14

acid, hypertonic solutions, fatty acids or monoglycerides in duodenum

Question 15

enterogastrones: what do they do and how do they do it

Answer 15

act to collectively prevent further acid build up in duodenum

2 strategies

• inhibit gastric acid secretion
• reduce gastric emptying (inhibit motility/contract pyloric sphincter)

Question 16

what is pepsinogen secreted by

Answer 16

cheif cells

Question 17

when is pepsinogen released

Answer 17

low pH (<3)

Question 18

what is gastric mucous produced by

Answer 18

surface epithelial cells and mucus neck cells

Question 19

role of gastric mucous

Answer 19

cytoprotective role

• protects mucosal surface from mechanical injury
• neutral pH –> protects against gastric acid corrosion and pepsin digestion

Question 20

intrinsic factor

Answer 20

produced by parietal cells
required for VitB12 absorption

intrinsic factor/b12 complex absorbed from ileum