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51 Cards in this Set
- Front
- Back
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What is the composition of pancreatic juice? its function?
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a water solution of enzymes and electrolytes (primarily HCO3-) that neutralizes acidic chyme and provides the optimal environment for pancreatic enzymes
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What does the composition of pancreatic juice depend on?
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depends on the types of foods in the chyme
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How much pancreatic juice is produced in a day?
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1 L
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What are the types of inactive enzymes the pancreas secretes as zymogens?
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proteases
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What are the types of enzymes the pancreas secretes as active enzymes?
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a-amylase (carbs)
lipase (lipids) etc, NON proteases |
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What initially cleaves trypsinogen in the epithelium of the small intestine? Where is it attached?
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enterokinase, which is attached to the epithelium of the small intestine
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What does trypsin cleave?
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itself, and all of the other proteases
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What is bicarbonate like in the small intestine?
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very concentrated
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What upregulates pancreatic secretion?
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lipids --> CCK
gastric acid --> secretin polypeptide YY |
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What does secretin cause? what does CCK cause?
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secretin: release of lots of pancreatic fluid and bicarbonate
cholecystokinin: secretion of enzymes |
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How does vagal nerve stimulation affect the pancrease?
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causes release of pancreatic enzymes
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How much bile is produced in a day?
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900 ml
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What is the purpose of bile?
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1. facilitate fat and cholesterol absorption through the formation of micelles
2. excretion of waste producs, especially bilirubin and cholesterol |
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What is bilirubin?
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a waste product of red blood cells
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Where is the gallbladder? What does it look like?
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on the ventral surface of the liver, thin-walled green muscular sac
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What does the gallbladder do with bile?
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stores and concentrates it (up to 20 fold)
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Via what duct does the gallbladder release bile?
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via the cystic duct
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What is bile derived from?
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cholesterol
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What is the sphincter of ampulla/sphincter of Oddi?
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muscular valve that controls the flow of digestive juices (pancreatic and bile) through the ampulla of Vadar into the second part of the duodenum
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What is the sphincter of ampulla/sphincter of Oddi relaxed by?
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CCK
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What effect do bile salts and secretion transported in the blood have on the liver?
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they stimulate the liver to produce bile
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What effect does vagal stimulation have on the gallbladder?
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causes weak contractions
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What effect does CCK have on the gallbladder?
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causes it to contract
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Where are bile salts reabsorbed? How much is lost in the feces?
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in the ilieum (95%); always 2-3% is lost in feces
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How much are bile salts reused?
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18x
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What are 4 causes of gallstones?
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1. Too much absorption of water from bile
2. Too much absorption of bile acids from bile 3. Too much cholesterol in bile 4. Inflammation of the epithelium |
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What is the impact of gallstones on the cystic duct?
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cholecystitis, biliary colic
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What is the impact of gallstones on the common bile duct?
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biliary colic and jandice
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What is the impact of gallstone obstruction on the ampulla of Vater?
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jaundice and signs of pancreatitis
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What is the impact of gallstone obstruction on the hepatic duct?
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either asymptomatic, jaundice, or inflammation
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What is jaundice?
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yellow tinge to the skin caused by hyperbilirubemia; represents a problem with the liver or biliary tract (w/bile production)
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What do Brunner's glands secrete? What upregulates them? What downregulates them?
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Alkaline Mucus (Mucin + HCO3)
+: Tactile or irritating stimuli on the duodenal mucosa Vagal stimulation Gastrointestinal hormones esp. Secretin -: Secretin |
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What do Brunner's glands do? (2)
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1. Protect the duodenal wall from digestion
2. Neutralize HCl |
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What is inside the crypts of Lieberkuhn?
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Globlet cells: mucins
Enterocytes (epithelial cells): water, electrolytes Paneth cells: Innate immunity |
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What is the pH of intestinal digestive juices?
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7.5-8.0
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What are the 2 secretions of the large intestine?
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HCO3 to neutralize bacterial acidity (NOT stomach pH)
Mucus - intestinal wall protection, bacteriostatic |
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How does the stomach digest protein?
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with pepsin
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What does the stomach absorb immediately?
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alcohol and caffeine
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As chyme enters the duodenum, what is the digestive state of carbohydrates, proteins, and fats?
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carbohydrates and proteins are partially digested; no fat digestion has taken place
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What are the folds in the mucosa of the small intestine called?
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Folds of Kirkring
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Where is most of the water in the GI system absorbed? How?
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95% of water is absorbed in the small intestines by osmosis, in the direction of the concentrate gradient established by solute uptake
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How are anions absorbed in the small intestine?
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most (ex. Cl-) follow the electrical potential established by Na+
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What does lactase divide lactose into?
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glucose and galactose
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How are carbohydrates absorbed?
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co-transported with Na+ and transported to the liver via the hepatic portal vein
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What transforms emulsified fat into fatty acids and 2-monoglycerides?
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pancreatic lipase
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Where do chylomicrons end up?
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in lymph
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What does re-export of cholesterol require?
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ATP
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What are chylomicrons?
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lipids combined with proteins
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How are nucleic acids absorbed?
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active transport via membrane carriers
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What is involved in Vit B12 absorption? What is another name for Vit B12?
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Vit B12 binds to IF and salivary protein R. Salivary protein R is degraded in the duodenum.
Another name for Vit B12 is Cobalamin (Cbl) |
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What effect do bacterial flora have on the digestive functions of the large intestine? (3)
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1. catabolize/ferment undigestible carbohydrates
2. synthesis of some vitamins (B complex and K) 3. water, ion, and vitamin absorption |
