Phys Gastric Secretion

Question 1

conc of HCl in stomach

Answer 1

approx 150 mN

Question 2

5 products secreted by stomach

Answer 2

Hydrogen ion
Pepsinogens
Mucus
IF
Water

Question 3

Purpose of IF

Answer 3

absorption of B12

Question 4

Pepsinogen function

Answer 4

cleaves internal peptide bonds

Question 5

3 acid purposes

Answer 5

anibacterial
activates pepsinogen to pepsin
denatures protein

Question 6

what cells excrete acid?
what cells excrete pepsin?
what cells excrete IF?

Answer 6

parietal cells
chief cells & mucous cells
parietal cells

Question 7

what is the only essential excretion of the stomach? What do you have to do after gastrectomy?

Answer 7

IF

administer B12

Question 8

compare veinous and arterial gastric blood when secreting acid?

Answer 8

veinous is more alkaline

Question 9

what enzyme allows formation of H+?

Answer 9

carbonic anhydrase (from CO2, OH-

Question 10

relationship of Cl- in acid production

Answer 10

excreted passively after antiported vs HCO3-

Question 11

what drives acid production in parietal cells?

Answer 11

NaKATPase, of course

Question 12

where is HCl excreted in parietal cells?

Answer 12

in tubulovesicles, which become continuous with lumenal side in glands

Question 13

3 stimuli that cause acid secretion & their intracellular messengers

Answer 13

vagus Ach (Gq IP3/Ca)
Gastrin (Gq IP3/Ca)
histamine (Gs cAMP)

Question 14

2 inhibitors of HCl production & their intracellular messengers

Answer 14

somatostatin & prostaglandins

Gi, cAMP down

Question 15

electrical potential outside cell on lumen side

Answer 15

80 mV

Question 16

which way do H and Cl go vs gradients?

Answer 16

H+ down electrical gradient

Cl- up electrical & conc gradient

Question 17

what do aspirin and ethanol do to potential difference between cell and lumen

Answer 17

Drop it synergistically

Question 18

tonicity of gastric secretions?

Answer 18

isosmotic

Question 19

how do gastrin and histamine relate in terms of acid secretion stim?

Answer 19

synergistic

Question 20

why does GERD get worse at night?

Answer 20

acid secretion increases until midnight

Question 21

peak acid secretion?

Answer 21

30 mEq/hr

Question 22

how does interest in food relate to acid secretion?

Answer 22

directly - the more you like it, the more you eat.

Question 23

what happens in absence of gastrin with vagal stimulation to parietal cells?

Answer 23

30% secretion anyway. (e.g. gastric bypass)

Question 24

3 stimuli to G cells & result

Answer 24

vagal stimulation (distention of stomach or sensory, Ach)
local reflexes/distention (Ach)
Digested protein

produces gastrin

Question 25

2 stimuli of ECL cells & result

Answer 25

Ach & Gastrin, histamine

Question 26

3 areas of GI that inhibit acid secretion & mediators

Answer 26

Stomach, somatostatin
Duodenum: secretin, nervous reflex
jejunum & duodenum: GIP

Question 27

how does acid secretion rate compare to pH & volume in stomach after feeding?

Answer 27

volume emptying goes fastest
pH follows
rate of acid secretion peaks later & is last to fall

Question 28

why doesn’t acid get secreted before feeding?

Answer 28

low pH inhibits gastrin release

Question 29

upon eating, 4 steps to acid secretion

Answer 29

vagal stim of parietal cells
pH goes over 3
gastrin secreted
higher acid secretion

Question 30

how does H pylori effect damage on stomach? Result?

Answer 30

damage to mucosal barier by NH4+ synth using urease. reduced acid
PUD

Question 31

acid levels in duodenal ulcers?

Answer 31

increased acid & pepsin