Phys Gastric Secretion Flashcards Preview

GI & Liver Fall 2013 CBD > Phys Gastric Secretion > Flashcards

Flashcards in Phys Gastric Secretion Deck (31):
1

conc of HCl in stomach

approx 150 mN

2

5 products secreted by stomach

Hydrogen ion
Pepsinogens
Mucus
IF
Water

3

Purpose of IF

absorption of B12

4

Pepsinogen function

cleaves internal peptide bonds

5

3 acid purposes

anibacterial
activates pepsinogen to pepsin
denatures protein

6

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

parietal cells
chief cells & mucous cells
parietal cells

7

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

IF

administer B12

8

compare veinous and arterial gastric blood when secreting acid?

veinous is more alkaline

9

what enzyme allows formation of H+?

carbonic anhydrase (from CO2, OH-

10

relationship of Cl- in acid production

excreted passively after antiported vs HCO3-

11

what drives acid production in parietal cells?

NaKATPase, of course

12

where is HCl excreted in parietal cells?

in tubulovesicles, which become continuous with lumenal side in glands

13

3 stimuli that cause acid secretion & their intracellular messengers

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

14

2 inhibitors of HCl production & their intracellular messengers

somatostatin & prostaglandins
Gi, cAMP down

15

electrical potential outside cell on lumen side

80 mV

16

which way do H and Cl go vs gradients?

H+ down electrical gradient
Cl- up electrical & conc gradient

17

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

Drop it synergistically

18

tonicity of gastric secretions?

isosmotic

19

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

synergistic

20

why does GERD get worse at night?

acid secretion increases until midnight

21

peak acid secretion?

30 mEq/hr

22

how does interest in food relate to acid secretion?

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

23

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

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

24

3 stimuli to G cells & result

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

produces gastrin

25

2 stimuli of ECL cells & result

Ach & Gastrin, histamine

26

3 areas of GI that inhibit acid secretion & mediators

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

27

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

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

28

why doesn't acid get secreted before feeding?

low pH inhibits gastrin release

29

upon eating, 4 steps to acid secretion

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

30

how does H pylori effect damage on stomach? Result?

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

31

acid levels in duodenal ulcers?

increased acid & pepsin