Gastrointestinal phys Flashcards
What secretes gastrin?
G cells in the antrum of the stomach
What regulates gastrin secretion?
Stomach distention, alkinization, amino acids, peptides and vagal stimulation all increase gastrin flow.
Very low pH stops the release of gastrin.
What secretes somatostatic?
D cells in the pancreatic islets.
What does somatostatin do?
Decreases gastric acid and pepsinogen.
Decreases gall bladder contraction.
Decress insulin and glucagon release.
Stimulated by acid decreased by vagal tone.
What releases cholecystokinin?
I cells in the duodenum and jejunum
What does cholecystokinin do?
Increase pancreatic secretion
Gallbladder contraction
Decreases gastric emptying
Increases sphincter of oddi relaxation`
Fatty acids and amino acids increase cholecystokinin release!!!
Where is secretin released from?
released from S cells in the duodenum leading to the release of HCO3- from the pancrease and slowing down of stomach emptyin.
also increases bile secretion.
What are the endocrine and exocrine effects of glucose dependent insulinotropic peptide (GIP)
Released by K cells in th duodenum
Exocrine: decreases gastric acid secretion.
Endocrine increases insulin secretion.
Why does oral insulin release more glucose than IV insulin?
Because of GIP release in the duodenum following oral stimulation.
What binds B12 and what creates it?
Intrinsic factor created from Parietal cells on the stomach.
Without it you get pernicious anemia.
What releases pepsinogen?
Chief cells in the stmach to help with protein digestion.
Where does gastrin exert most of its effects?
It can work directly on the parietal cells but it mostly works on the enterochromafin cells that produce histamine which greatly upregulat H+ secretion from the parietal cells.
What channel is repsonible for secreting H+ into the stomach/
H+/K+ ATPase.
How does the ion concentration change in pancreatic secretions based on flow levels
Low flow it is high Cl-
High flow its high in HCO3-
What sugar channel absorbes glucose and galactose?
SGLT1
What sugar channel takes up fructose?
GLUT-5
What channel moves all sugars into the blood?
GLUT-2
What are the main vitamins/minerals absoarbed in the small bowel?
Iron in the duodnum as Fe2+
Folate in the small bowel.
B12 i the ileum with bile salts requiring intrinsic factor.
Where are peyer patches found?
These are found in the lamina propria and submucosa of ileum. Contain specialized M cells that sample material.
What is the major antibody formed by B cells in the peyers patches?
IgA
