L30 - GIT Secretions II Flashcards
Feb 26, 2019
Prostaglandins increase secretion of what in the stomach?
Bicarbonate
The pancreas secretes digestive enzymes as well as what other exocrine secretion?
Bicarbonate
The pancreas’ secretions are decreased in chloride but increased in which ion?
Bicarbonate
When pancreatic flow rate is high, which ion is secreted more?
Bicarbonate
Ductular cells secrete which ion?
Bicarbonate
Secretin increases secretion of which ion? CCK increases secretion of which ion? Acetycholine stimulation through the vagal nerve increases production of which ion?
1) Bicarbonate
2) Bicarbonate
3) Bicarbonate
In ductular cells, chloride leaks out but is pumped back in through exchange with which ion?
Bicarbonate
An increase in calcium concentration causes an increase in secretion of what?
1) chloride
2) zymogen granules
CCK and ACh cause an increase in what secretions?
Increase in release of zymogens
Pancreatic acinar cells secrete what?
1) Na and Cl ions
2) digestive enzymes
If the flow rate is low, what ion is increased in pancreatic secretions?
Chloride
The NKCC transpors which ions?
sodium, potassium, and chloride (x2)
Why is there an increase in mucus viscosity in cystic fibrosis?
CFTR is a chloride channel which expels chloride ions into the pancreatic ducts. In CF, this does not work, causing a decrease in lumen negativity which will decrease sodium and water transport into the lumen, thus causing decreased watery secretions
How much of the pancreatic secretions are accounted for by the cephalic phase of digestion? Gastric phase? Intestinal phase?
Cephalic: 25%
Gastric: 10%
Intestinal: 50-80%
What is the major contributor of pancreatic secretion in the cephalic phase?
Autonomic parasympathetic stimulation through the vagal nerve (acetylcholine
What are the two major stimuli that control pancreatic enzyme secretion in the gastric phase?
1) gastric distention
2) protein in food
In the gastric phase, gastric distention works through what mechanism? What about protein in food?
Gastric distention –> increased vagal response –> stimulated acetylcholine receptors –> increased enzymatic secretion
Protein in food –> increased gastrin –> stimulation of gastrin/CCK receptors –> increased enzymatic secretion
What two stimuli produce increased pancreatic secretion in the intestinal phase?
1) digestive products present
2) H+ in the lumen
What cells respond to H+ content in the lumen of the intestine? Where are they? What do they secrete? Does this secretion act on the H+ itself or through another mechanism?
1) S cells
2) intestinal mucosa
3) secrete secretin
4) secretin acts to increase bicarb secretion in the pancreatic ductular cells by increasing cAMP
What are the two mechanisms that are stimulated when digestive products are present?
1) vagovagal reflex
2) duodenal I cells
What do duodenal I cells secrete?
CCK
Which digestive products produce the largest CCK response? Smallest?
Largest: FAs
Smallest: Carbs
CCK and secretin act by giving the pancreas time to digest food. How?
Inhibit gastric motility and secretion
What two proteins drive fluid secretion from the crypts of the small intestine?
CFTR and CACC
