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48 Cards in this Set
- Front
- Back
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What secrete enzymes in the pancreas? What secrete Bicarbonate?
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Acini secrete enzymes. Ducts secrete bicarbonate.
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What is the papila of Vater?
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The union of the pancreatic duct and the common bile duct (union of hepatic and cystic ducts). The papila of vater is surrounded by the Sphincter of Oddi.
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T/F The secretion of pancreatic juice depends on the contents of the chyme
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True.
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How is bicarbonate secreted into the pancreatic juice?
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Via the ducts.
CO2 diffuses into the duct cells, reacts with CA to form bicarbonate and H+. The H+ is then exchanged with Na+ in the blood. Now you have bicarbonate which can move into the lumen. This brings along with it water. |
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What types of food can pancreatic enzymes digest?
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All types. PRotein fat and carb
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What are the fat digesting enzymes in the pancreas juice?
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Pancreatic lipase- triglycerides to monoglycerides and FA.
Cholesterol esterase-hydrolyzes cholesterol. Phospholipid lipase-splits fatty acids from phospholipids. |
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What are the CHO digesting enzymes in the pancreas juice ?
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Pancreatic amylase - breaks carbs into DI and TRI saccharides.
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What are the protein digesting enzymes of the pancreas juice?
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Trypsin,
Chymotrypsin Carboxypeptidase |
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What is the difference in function between trypsin, chymotrypsin, and carboxypeptidase?
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Carboxypeptidases cleave substrate into individual AA.
Trypsin/chymotrypsin only break into smaller peptides. |
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How are trypsinogen, chymotrypsinogen, and procarboxypeptidase activated?
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Upon arrival to intestinal tract, enterokinase (secreted by intestinal epithelium in response to chymes presence) activates trypsinogen to trypsin, which activates everything else. Free floating trypsin can also self activate trypsinogen.
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How do you prevent against premature activation of typsinogen in the acini and pancreatic ducts? When is this mechanism overriden
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The acini secrete trypsin inhibitor, which prevents premature activation in the acini and ducts.
This protective mechanism is overriden in cases of blocked ducts, leading to pancreatitis. |
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What 3 stimuli stimulate pancreatic secretion?
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Acetylcholine, cholecystokinin, and secretin.
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How does ACh stimulate pancreatic secretion? How does CCK stimulate pancreatic secretion? How does Secretin stimulate pancreatic secretion?
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ACh stimulates pancreatic stimulation by stimulating Acini, not ducts. CCK stimulates Acini, not ducts in response to protein/fat presence. Secretin stimulates the ducts (bicarbonate fluid production) in response to acid levels in SI
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What kind of cells release CCK? What prompts its release? What percent of pancreatic enzyme secretion does CCK account for?
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I Cells.
Protein breakdown (peptones,proteoses). 75% |
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What are the 3 phases of pancreatic secretion?
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Cephalic phase- ACh release causes enzyme release but no fluid (20% total volume) .
Gastric phase- Continuation of cephalic phase; adds 10%, little flow Intestinal phase - Chyme entry into the duodenum causes CCK, secretin to be released- vast secretion. |
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What are the 2 functions of bile?
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1) Emulsifies fat/helps aid in absorption too
2) Means for excretion of blood waste products (cholesterol, billirubin) |
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What are the stages of bile secretion?
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hepatocytes secrete bile acids and cholesterol into the bile canaliculi, which flow into the interlobar septa, reaching the common hepatic duct. The ducts secrete weak bicarbonate solution to assist in acid neutralization. The bile is then stored in GB or released into duodenum
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How much bile can the GB store? How does it make up for this?
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50 mL. Primary active transport removes a sodium, and then water and chloride etc are all removed, leaving a very concentrated
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What is the composition of bile?
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50% Bile acids (CHOLIC acid and derivatives - made from cholesterol and 7a hydroxylase; conjugation to taurine/glycine brings pk down)
Phospholipids (lecithin) Cholesterol Bile pigment (billirubin glucoronide) |
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Briefly review billirubin metabolism.
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Heme breakdown yields billirubin. This forms an adduct with billirubin,which enters the liver and gets the gluconoride attachment. It is then eliminated as urobilin in the urine or sent to the intestine -> urobilinogen -> stercobilin.
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How does gallbladder emptying vary when there is fat vs when no fat in the meal?
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Gall bladder empties in 1 hr for a fatty meal (CCK present).
Gall bladder emptying is poor if no fat. |
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What are the 2 factors that affect empyting of the gall bladder?
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They are 2 of the same ones that affect pancreatic secretions. ACh and CCK (more potent)
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What % of fats could not be absorbed without bile?
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40%
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What is the enterohepatic circulation?
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The enterohepatic circulation reflects the reabsorption of bile into from the small intestine.
50% is diffusion, 50% active transport. |
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What % of bile is lost in feces?
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6%
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What is the role of secretin in bile secretion?
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Secretin increases bile secretion strongly but this effect is not as important as secreting HCO3 solution to neutralize acid.
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How is cholesterol kept in solution in bile?
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Forms micelles with bile salts and lecithins.
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What are 2 ways in which gallstones can form?
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Precipitation of cholesterol
Irritation of epithelium |
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What are Brunner's glands? where do you find them?
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These are duodenal mucous glands that protect the duodenum from acidic degredation by neutralizing HCl.
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What are Brunner's glands? where do you find them?
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These are duodenal mucous glands that protect the duodenum from acidic degredation by neutralizing HCl.
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What promotes and inhibits Brunner's glands?
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Inhibition- Sympathetic - stress can give you an ulcer.
Stimulation - irritating stimuli, vagal stimulation, secretin. |
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What promotes and inhibits Brunner's glands?
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Inhibition- Sympathetic - stress can give you an ulcer.
Stimulation - irritating stimuli, vagal stimulation, secretin. |
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Where are the small crypts of Lieberkuhn found? What kind of cells make them up?
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Between the intestinal villi of the small intestine. Goblet cells and enterocytes. The goblet cells produce mucus, and the enterocytes make a fluid that is like ECF.
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Where are the small crypts of Lieberkuhn found? What kind of cells make them up?
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Between the intestinal villi of the small intestine. Goblet cells and enterocytes. The goblet cells produce mucus, and the enterocytes make a fluid that is like ECF.
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What are Brunner's glands? where do you find them?
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These are duodenal mucous glands that protect the duodenum from acidic degredation by neutralizing HCl.
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How is the watery fluid secreted in the crypts of Lieberkuhn? What is the function of this fluid
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HCO3- and CL- are secreted, dragging Na+ across too. This creates an osmotic gradient for water.
These secretions are quickly absorbed by the villi, which absorb chyme with it. |
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How is the watery fluid secreted in the crypts of Lieberkuhn? What is the function of this fluid
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HCO3- and CL- are secreted, dragging Na+ across too. This creates an osmotic gradient for water.
These secretions are quickly absorbed by the villi, which absorb chyme with it. |
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What promotes and inhibits Brunner's glands?
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Inhibition- Sympathetic - stress can give you an ulcer.
Stimulation - irritating stimuli, vagal stimulation, secretin. |
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Does LI have villi? Does large intestine secretion have enzymes?
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No villi. No enzymes in the secretion.
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Does LI have villi? Does large intestine secretion have enzymes?
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No villi. No enzymes in the secretion.
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Where are the small crypts of Lieberkuhn found? What kind of cells make them up?
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Between the intestinal villi of the small intestine. Goblet cells and enterocytes. The goblet cells produce mucus, and the enterocytes make a fluid that is like ECF.
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How is the watery fluid secreted in the crypts of Lieberkuhn? What is the function of this fluid
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HCO3- and CL- are secreted, dragging Na+ across too. This creates an osmotic gradient for water.
These secretions are quickly absorbed by the villi, which absorb chyme with it. |
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Does LI have villi? Does large intestine secretion have enzymes?
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No villi. No enzymes in the secretion. No digestive enzymes at all in fact for the large intestine
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What are the digestive enzymes in the SI?
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The peptidases (split into individual AAs), enzymes to split disaccharides, and intestinal lipase (triglyceride splitting) are located in the brush border.
NOTE The small intestine, like the large intestine, does not have the digestive enzymes in its secretion. The small intestine, unlike the large intestine, has digestive enzymes in the BRUSH BORDER. |
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What are the digestive enzymes in the SI?
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The peptidases (split into individual AAs), enzymes to split disaccharides, and intestinal lipase (triglyceride splitting) are located in the brush border.
NOTE The small intestine, like the large intestine, does not have the digestive enzymes in its secretion. The small intestine, unlike the large intestine, has digestive enzymes in the BRUSH BORDER. |
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What are the factors that affect SI secretion?
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MORE CHYME, MORE SECRETION
ENS control relfexes in response to irritating stimuli or increased activity in response to increased motility CCK, secretin |
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What are the secretions of the LI like?
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The LI has many crypts of Lieberkuhn- primary secretions are mucous through the goblet cells. Pelvic nerve parasympathetic stimulation and tactile stimulation on LI surface increase secretion.
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What are the functions of secreting from the LI?
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Hold fecal matter together
Prevent excoriation Protect against bacteria in the fecal matter attacking LI Protects against acid damage from fecal matter |
