GI physiology 2 Flashcards
(30 cards)
which cells secrete pepsinogen
chief cells
T/F pepsinogen is NOT a zymogen. And what is a zymogen
F
Precursor, pepsinogen is a precursor to pepsin
Pepsinogen IS mediated by input from _______ nervous system (ACh)
A)PARASYMPATHETIC
B)SYMPATHETIC
C) ENTERIC
ALL but C is what it is mediated by which is para and symp
what type of enzyme is pepsin
proteolytic/protease
T/F
Conversion of pepsinogen to pepsin is pH dependent
T
what pH is optimal for conversion of pepsinogen to pepsin
2
what type of feedback loop is conversion of pepsinogen to pepsin
positive
what creates the optimal pH for pepsinogen conversion to pepsin
low pH from HCL
what cell produces HCL for optimal pH of 2 for conversion of pepsinogen to pepsin
parietal
pepsin main function
Pepsin breaks down dietary proteins reaching the stomach into amino acids
what % of protein digestion does pepsin account for
A)30
B)10
C)50
D)20
E)80
D
What is the aprx volume of an empty stomach
50 mL
what is the aprx volume a stomach can handle while eating
1.5 L
_____ muscle in the body and fundus undergoes receptive relaxation
A)smooth
B)skeletal
C)cardiac
A
Receptive relaxation is mediated by _______ nervous system acting on enteric nerve plexuses
A)sympathetic
B)parasympathetic
B
define receptive relaxation
Receptive relaxation is a reflex in which the gastric fundus dilates when food passes down the pharynx and the oesophagus.
which nerve coordinates receptive relxation
A)vagus
B)glossopharngeal
C)abdeucean
D)phrenic
A
which 2 neurotransmitters released by enteric nerves mediate receptive relaxation
Nitric oxide
serotonin
what is peristalsis
contractive waves beginning in gastric body (weakest)
in peristalsis where does the more powerful contractions occur
gastric antrum and pyloric closes as wave reaches
function of peristalsis
churns and transports food
Frequency of peristaltic waves determined by ______ _____ in muscularis propria and is constant (3/minute)
pacemaker cells/intersticial cells of cajal
T/F
Interstitial cells of cajal/pacmaker cells undergo fast depol and repol
F
slowly repol and depol
Gastrin is triggered by _____ and ____
ACh
stretch receptors
