Flashcards in Ward: Small and Large Intestine Secretion and Absorption Deck (55)
Two components of the pancreas
islets of Langerhans
carbohydrate enzyme (pancreatic amylase)
List the three proteolytic enzymes released from the pancreas
What activates trypsinogen to trypsin?
What activates chymotrypsinogen to chymotrypsin?
Released from glandular cells and inhibits the activation of trypsin inside the secretory cells, in the acini and in the pancreatic ducts
In pancreatic acinar cells, enzymes are condensed into vacuoles and concentrated to form (blank), which can fuse with the apical membrane and rupture to release its contents
Enzymes of the pancreas are secreted by (blank)
When the pancreas releases pancreatic enzymes, it also releases (blank) and (blank)
water; bicarbonate ions
The (blank) and (blank) concentrations in pancreatic secretion are approximately similar to that of plasma, but (blank) ion secretion is lower. The (blank) ion secretion increases with secretion rate
Na+; K+; Cl-; bicarbonate
How is bicarbonate secreted from pancreatic cells?
Na/H+ exchanger pumps H+ in
H+ forms H20
H20 combines with CO2 to form bicarb which is shuttled out into the lumen in exchange for Cl-
As Cl- moves down its concentration gradient into the lumen, (blank) follows, which pulls water with it into the lumen.
What is HCO3 secretion dependent upon?
The availability of Cl- in the lumen. Ultimately the opening of Cl- channels on the apical membrane.
As secretory rate increases, conc. of bicarb (blank)
As concentration of bicarb in the lumen increases, the concentration of Cl- (blank)
4 stimuli important for stimulating pancreatic secretion
released from parasympathetic vagus nerve terminals in the ENS
released during the gastric phase of the stomach
secreted by duodenal mucosa when food enters the duodenum
secreted when low pH products enter the stomach (neutralizes pH)
ACh and CCK activate (blank), while secretin activates (blank)
Ca+ stores; cAMP
During the cephalic and gastric phases, ACh and gastrin cause relatively (blank) pancreatic secretion
Pancreatic secretion is increased considerably when chyme enters the duodenum, in response to the hormones (blank) and (blank).
released from S cells in the mucosa of the upper small intestine. The stimulus for release is gastric acid and long chain fatty acids.
The release of (blank) during the intestinal phase of pancreatic secretion increases the pH of the luminal contents so it is more optimal for pancreatic enzymes
Released from I cells within the mucosa of the duodenum and upper jejunum. The stimulant that causes the release appears to be proteoses and peptones
Two important functions of the secretion of bile into the GI tract
1. emulsifies large fat particles into smaller ones
2. serves as a means of excretion of waste products
Two primary bile acids from cholesterol
Constituents of bile
Major phospholipid found in bile