GI phys Flashcards
what are the 3 types of gastric glands
Mucosal (neck) cells- secrete mucus and gastine
chief
parietal
what cells produce gastrin
G cells (in mucosal neck cells)
What doe chief cells produce/secrete
produce pepsinogen
(in presence of hydrochloric acid, pepsinogen is activated to form pepsin- necessary for pro digestion)
What do parietal cells secrete
secrete hydrochloric acid and intrinsic factor
What is HCL and intrinsic factor used for
HCL is needed for activation of pepsinogen
Intrinsic factor necessary for absorption of Vit B12
what does chyme in s intestine stimulate
stims release of secretin from S-cells found in duodenum
What does secretin do
stims pancreatic acinar cells to release bicarbonate and water
what does bicarbonate do
(also secreted by brunners glands, along with pancreatic ancinar cells)
-neutralizes the gastric acid and makes Ph alkaline
-protects duodenal walls
What does the presence of fat in duodenum stim
Cholecystokinin (CCK) by the I cells of duodenum
-CCK causes gallbladder to contract ad sphincter of Oddi to reps
what do the exocrine cells of the pancreas release
-Trypsinogen- activated by trypsin which starts pro digestion
-Pancreatic amylase- digestion of starch
-lipase- breaks down fat into fatty acids and glycerol
What are the endocrine cells releasing in pancrease
Arranged into the islets of langerhans:
-glucagon
-insulin
-somatostatin
What type of specialized cells of the Large intestine release
numerous goblet cells which secrete mucus to aid in passage of faces
What are the fat soluble vits
DAKE
where is folic acid and iron absorbed
in jejunumm
what transfers iron in blood to cells in the liver, spleen and bone marrow
transferrin
How is vit B12 absorbed
attached to intrinsic factor
complex is delivered to the terminal ileum where it is bound to cubilin receptor on the enterocytes and transport into the enterocytes
Bilirubin metabolism steps
RBC broken to heme and globin
Heme is broken into biliverdin and iron
biliverdin is converted to bilirubin which is carried in blood attached to albumin
transported to liver where its conjugated (water soluble)- excreted by gallbladder
fate of bilirubin in the gut
converted by bacteria to urobilinogen where its absorbed and excreted in urine
-the rest of urobilinogen in gut is converted to stercobilinogen which is oxidized to sterocobilin in stool
What is gastric inhibitory peptide secreted by and what does it do
secreted by K cells
-decreases gastric acid secretion
What does glucagon like peptide 1 do and secreted by
secreted by K cells in duodenum and jejunum
-inhibits gastric emptying
What does gherkin do
Released by P cells in stomach
-increased before meals and decreased after
