GI ML: 4 Flashcards
What are the three functional regions of the stomach
-fundus
-body
-antrum
What is the fundus job
it has a flexible size and it is smooth and weak to allow it to stretch for the bolus
What is the job of the lower esophageal sphincter?
prevention of reflux
What is the job of the body
secretes mucus, pepsinogen, and HCL and has notable rugae and is thicker and stronger
What is the job of the antrum
mixing and grinding, secretes mucus, pepsinogen and gastrin
What does the pyloric sphincter do?
controls stomach emptying
What is the first part of the small intestine
duodenum
What is the job of the stomach
it is a storage organ
What are gastric pits also known as
crypts
What do mucous cells secrete
mucus, bicarbonate secretion
What do parietal cells secrete
exocrine; acid (HCl) and intrinsic factor secretion
What do ECL cells secrete
histamine secretion (paracrine, so it will act on the parietal cell)
What do chief cells secrete
pepsinogen
What are the two endocrine cells and what do they secrete
D= somatostatin
G= gastrin
-both of these will act on paritel cells
What hormones will increase HCL secretion
gastrin, histamine, and ACh
The release of Ach will be triggered by what
ENS and para
What hormone inhibits HCl secretion
somatostatin
OCT anaracid tablets
neutralize HCL when produced
What are some examples of anatacids
TUMS, rolaids
Histamine blockers
act on histamine and block receptors, decrease amount of vesicles fusing, so decreases number of pumps
examples of histamin blockers
tagamet and zantac
Proton pump inhibitors
inhibit action of proton pumps so it reduces pumping; doesnt affect number of pumps but decreased HCl production
Examples of proton pump inhibitors
prilosec, nexium
Control of HCL secretion during the cephalic phase
increased HCL secretion due to parasymp nerves to enteric nervous system
Control of HCL secretion during gastric phase
increased secretion due to long and short reflexes and gastrin
control of hcl during intestinal phase
secretin, cck, and reflexes inhibit Hcl secretion
Why do nutrients in the SI have an inhibitory effect on both tomach secretion and motility
so small intestine isn’t damaged by too much HCL
Pepsinogen is an inactive____
zymogen
How is pepsinogen activated
by H+ and pepsin to pepsin or hcl
Is pepsin essential
no, pancreas proteases adequate alone
What are the four motilities of the stomach
receptive relaxation
peristalic wave
retropulsion
gastric emptying
When does receptive relaxation occur
cephalic into gastric phase
Where does receptive relaxation occur
in the fundus to stretch for the bolus
What is receptive relaxation
increase in lumen volume
What stimulates receptive relaxation
serotonin and nitric oxide
What is happening during the peristaltic wave
begins in the body and wave approches sphincter it closes and very little chyme goes through
what is happening during retropulsion
occurs in antrum and it contracts in the opposite direction
How are motilites in the stomach controlled
slow waves are spontanoues electric events
Waves are depolarized and hyperpolarized by
location of bolus
ENS
Hormones
ANS
What is happening during gastric emptying
chyme moved into small intestine
What is gastric emptying stimulated by
stomach stretch and chyme fluidity
What is gastric emptying inhibited by
enterogastric reflex
What is the digestion in the stomach
mechanical: physical grinding and breaking down chyme
chemical: proteins broken into peptides and H+ allows digestion
What is the absorption in the stomach
not much
-weak acids and alcohol
