HRR: secretions II Flashcards
Describe secretin
Made by S cells in the duodenum in response to low pH and fatty acids that lowers gastrin secretion, increases bile synthesis, and stimulates pancreatic ductal cells to make bicarb.
Describe CCK
Made by I cells in the duodenum and jejunum in response to fatty acids and amino acids that reduces gastric activity and boosts activities of the intestines such as bile synthesis, gall bladder contraction, relaxing sphincter of Oddi, and stimulating release of pancreatic digestive enzymes.
Describe peptide YY
Made by L cells of the distal small intestine/proximal colon in response to fatty acids that decreases HCl secretion and decreases both gastric emptying and intestinal motility.
Describe GLP
Secreted by L cells in the distal small intestine in response to AA, FA, and oligosaccharides that slows GI motility and gastric emptying, inhibits gastric acid secretion, and enhances absorption by promoting growth of intestinal mucosa (GLP-2).
Describe GIP
Made by K cells in the duodenum and jejunum in response to oligosaccharides that decreases gastric acid, slows gastric emptying, and stimulates insulin.
What is the exocrine pancreas responsible for secreting?
HCO3 and digestive enzymes.
___ secrete digestive enzymes and ___ secrete bicarb in the pancreas.
Acini, ductal cells.
What stimulates zymogen granules to be released in the acinar cells?
Ach, GRP, CCK, some secretin.
What stimulates bicarb fluid secretion from ductal cells?
Secretin.
What role do CFTR channels play in the pancreas?
They allow outflow of chloride into the ductal lumen to draw water in; secretion could be super thick without it.
What is exocrine pancreatic insufficiency?
Deficiency of pancreatic digestive enzymes; causes bloating, diarrhea, steatorrhea, fat-soluble vitamin deficiency.
What are Brunner’s glands?
Glands in the submucosa of proximal duodenum that secrete bicarb and mucin-rich fluid to neutralize chyme.
What drives intestinal fluid secretion?
Active secretion of chloride from crypt cells! This draws sodium with it, which will in turn draw water.
What may result from chloride channels being open for too long?
Diarrhea.
What are the motility patterns of the small intestine?
Segmentation, peristalsis, MMC.
What is segmentation?
A pattern of rhythmic churning that mixes contents and aids in absorption. It does not function to propel contents forward.
What is peristalsis?
Contractions that move contents forward.
What are migratory motor complexes (MMC)?
Peristaltic contractions at rest.
Where is the highest frequency of MMC?
Small intestine.
What is the role of scleroderma in GI?
These patients may have intestinal dysmotility and poor peristalsis, resulting in stagnancy and bacterial overgrowth.
What are the motility roles of the colon?
Segmentation via haustral contraction and propulsion.
The colon is a net secretor of…
Potassium.
