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Questions and Answers
What is the primary consequence of abnormalities in the preparatory and transport phases of lipid absorption?
What is the primary consequence of abnormalities in the preparatory and transport phases of lipid absorption?
Which condition is NOT listed as a cause of bile flow obstruction?
Which condition is NOT listed as a cause of bile flow obstruction?
Which of these phases are involved in lipid digestion and absorption?
Which of these phases are involved in lipid digestion and absorption?
What is tropical sprue associated with?
What is tropical sprue associated with?
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What is the normal percentage of ingested fat excreted in feces?
What is the normal percentage of ingested fat excreted in feces?
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What stimulates the secretion of electrolytes and fluid components of pancreatic juice?
What stimulates the secretion of electrolytes and fluid components of pancreatic juice?
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What causes the contraction of the gallbladder?
What causes the contraction of the gallbladder?
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Which of the following does NOT directly stimulate the secretion of pancreatic juice?
Which of the following does NOT directly stimulate the secretion of pancreatic juice?
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What stimulates the secretion of the pancreatic enzymes?
What stimulates the secretion of the pancreatic enzymes?
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What is the role of acid chyme in the small intestine?
What is the role of acid chyme in the small intestine?
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Which enzyme breaks down triglycerides into monoglycerides and fatty acids?
Which enzyme breaks down triglycerides into monoglycerides and fatty acids?
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What does Phospholipase A2 break down phospholipids into?
What does Phospholipase A2 break down phospholipids into?
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How are short-chain fatty acids absorbed?
How are short-chain fatty acids absorbed?
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What is the fate of long-chain fatty acids during absorption?
What is the fate of long-chain fatty acids during absorption?
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Where does free glycerol taken after being released in the intestinal lumen?
Where does free glycerol taken after being released in the intestinal lumen?
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Study Notes
Digestion of Lipids
Digestion in Small Intestine
- Pancreatic juice contains lipolytic enzymes that break down lipids:
- Lipase breaks down triglycerides into monoglycerides and fatty acids
- Phospholipase A2 breaks down phospholipids into lysolecithin and fatty acids
- Cholesterol esterase breaks down cholesterol esters into cholesterol and fatty acids
Stimulation of Pancreatic Juice Secretion
- Acidic gastric contents (acid chyme) entering the duodenum stimulate pancreatic juice secretion
- GI hormones also stimulate secretion:
- Secretin increases secretion of electrolytes and fluid components
- Pancreozymin (CCK-PZ) stimulates secretion of pancreatic enzymes
- Cholecystokinin (CCK-PZ) causes gallbladder contraction and bile discharge into the duodenum
Absorption of Lipids
- Glycerol is absorbed directly into the portal vein and taken to the liver
- Fatty acid absorption varies based on carbon content:
- Short-chain, medium-chain, and unsaturated FAs are absorbed into portal blood and taken to the liver
- Long-chain FAs are absorbed, re-esterified into TG, and enter the lymphatic system
Clinical Significance
- Steatorrhoea occurs due to abnormalities in lipid digestion and absorption:
- Biliary obstruction
- Pancreatic diseases
- Tropical sprue (abnormal villi and inflammation of the lining epithelium)
- Normally, less than 0.5% of ingested fat is excreted in feces
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Description
This quiz covers the digestion of lipids in the small intestine, including the role of pancreatic juice lipolytic enzymes, and the absorption of lipids.
