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MBC - Lecture 45
Digestion and Absorption I (Mock)
| Question | Answer |
|---|---|
| Lecture 45 | Digestion and Absorption I |
| Salivary Glands | Production of fluid and digestive enzymes for homogenization, lubrication and digestion of carbohydrates (amylase) and lipids (lingual lipase) |
| Stomach | Secretion of HCL and proteases to initiate hydrolysis of proteins |
| Pancreas | Secretion of HCO3, proteases, lipases, and amylase to continue digestion of proteins, lipids, and starch |
| Liver and Gall Bladder | Secretion and storage of bile acids for release to small bowel |
| Small Bowel | Final intraluminal digestion of foodstuffs, membrane digestion of carbohydrate dimers and specific absorptive pathways for digested materials |
| Large Bowel | absorption of fluid and electrolytes and products of bacterial action in the colon |
| Three acid secretagogues are: | acetylcholine, gastrin, histamine |
| Gastrin is a ___ hormone produced by G cells in the ___, ___, and ___. | peptide, duodenum, pyloric antrum, and pancreas |
| Zollinger Ellison Syndrome | Gastrinoma, hypergastrinemia in the pancreas |
| Cause for release of gastrin is: | stomach distention, vagal nerve stimulation, products of protein digestion |
| Gastrin is secreted in the ___. | bloodstream |
| “Big Gastrin” | Gastrin-34 |
| “Little Gastrin” | Gastrin-17 |
| “Mini-Gastrin” | Gastrin-14 |
| Pentagastrin | Synthetic (only first 5 residues required to emulate effects of gastrin) |
| Gastrin binds to the ___/___ receptor on the ___ (ECL) cell. | CCK2/gastrin, enterochromaffin-like |
| Gastrin secreted into the blood by the ___ binds and stimulates ECL cells to secrete ___. | duodenum, histamine |
| Two important types of acid secretion blockers are: | histamine (H2) receptor blockers and proton pump inhibitors |
| Parietal cells have ___ receptors. | histamine |
| Histamine from secreted by nearby ___ cells bind to the parietal cell receptors. | ECL cells |
| Parietal cells pump ___ into the lumen of the body. | protons |
| Histamine is an ___ for pumping of protons into the lumen of the stomach. | agonist |
| Histamine receptor blockers: | cimetidine (Tagamet), ranitidine (Zantac), famotidine (Pepsid) |
| Parietal cells have ___ pumps. | proton |
| Proton pumps are ___/___ exchanging ATPases. | K+/H+ |
| Proton pump inhibitors: | omeprazole (Prilosec), lansoprazole (Prevacid), esomeprazole (Nexium), pantoprazole (Protonix) |
| Three macronutrients: | protein, carbohydrate, lipid |
| Pepsin A initiates ___. | protein digestion |
| Pepsinogens are ___. | zymogens |
| Pepsin A is secreted from ___ cells. | chief |
| Zymogens in the pancreas are ___, preventing inappropriate enzyme cascades. | inactive |
| Pancreatitis | Abdominal pain/increased plasma amylase and lipase/stone in ampulla of vater, congenital tendency of trypsinogen activation and defective trypsin inhibitor |
| Polypeptides in the lumen are cleaved to ___ and ___ on the luminal surface. | free amino acids and oligopeptides |
| Oligopeptides are cleaved to ___, ___, and ___ before entering the enterocyte. | amino acids, dipeptides, and tripeptides. |
| Hartnup’s Disease (Neutral Aminoaciduria) | SLC6A19 (neutral amino acid transporter) is defective, tryptophan and nicotinamide deficiency, pellagra-like presentation/cerebellar ataxia |
| Starch cleaved to ___ and ___ by α-amylase in the lumen. | maltose and maltoriose |
| Maltose and maltoriose catalyzed by ___ produces glucose. | maltase (enterocyte) |
| α-dextrin catalyzed by ___ produces glucose. | oligosaccharidase (enterocyte) |
| Sucrose cleaved to ___ and ___ by sucrase in the enterocyte. | fructose and glucose |
| Lactose cleaved to ___ and ___ by lactase in the enterocyte. | galactose and glucose |
| Glucose is ___ transported out of the enterocyte. | actively |
| Fructose leaves the enterocyte by ___. | facilitated diffusion |
| Effects of injury on digestive-absorptive functions are not ___. | uniform |
| Intestinal digestive-absorptive functions are ___ susceptible to mucosal injury. | not equally |
| Fat absorption is ___% efficient over a wide range. | 98% |
| Typical substrates of emulsification: | long chain, triglycerides |
| Typical substrates of enzymatic hydrolysis and micellar solubilization: | long chain, triglycerides, sterol esters, phospholipids |
| Typical substrates of only enzymatic hydrolysis: | esterified short chain |
| Typical substrates of only micellar solubilization: | vitamins A/D/E/K, cholesterol |
| ___ produced during gastric lipolysis help emulsify fat in the stomach. | Fatty acids |
| Acid Lipase | Source: lingual glands/gastric mucosa, Action Site: stomach/small intestine |
| Pancreatic Lipase-Colipase | Source: pancreas, Action Site: small intestine |
| Carboxyl Ester Lipase | Source: pancreas/human milk, Action Site: small intestine |
| Phospholipase A2 | Source: pancreas, Action Site: small intestine, main phospholipid lipase |
| Lipase cleaves triacylglycerol to ___ and ___. | fatty acids and monoacylglycerol |
| Triglyceride lipases have different ___ specificity. | positional |
| Acid lipase cleaves triglycerides to ___ and ___. | fatty acid + diglyceride |
| Pancreatic lipase-colipase cleaves triglycerides to ___ and ___. | fatty acids and 2-monoglyceride |
| Olestra | Fatty-acylated sucrose with vitamins A/D/E/K, may cause abdominal cramping and loose stools, inhibits absorption of some vitamins and nutrients |
| Orlistat (Xenical) | Pancreatic lipase inhibitor, saturated derivative of lipstatin (natural pancreatic lipase inhibitor), true steatorrhea/anal oil leaking |
| Pancreatic Carboxyl Esterase | Catalyzes (back-up) hydrolysis of long chain triglycerides and primary enzyme in digestion of dietary cholesterol |
| Mechanism of Phospholipase A2: | Hydrolyze C2 side chain |
| Newborn pancreatic lipase levels is ___% of adult levels. | 2-5% |
| Breast milk provides additional ___. | lipase |
| Pancreas in a newborn becomes active after ___ months. | 3 to 6 months |
| Fecal content of pancreatic insufficient individuals (i.e. CF) contain ___% of fat intake. | 50% |
| Steatorrhea | Presence of excess fat in feces |
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