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What are micelles and what do they contain?
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Micelles are small droplets containing monoglycerides, free fatty acids, cholesterol, and fat-soluble vitamins (A, D, E, K).
What are the distinguishing features of chylomicrons in terms of composition?
Chylomicrons consist of 1% protein and 90% triglyceride.
Describe the process of emulsification in the exogenous pathway.
Bile salts emulsify large fat globules into small droplets, allowing pancreatic lipase to break down triglycerides into monoglycerides and free fatty acids.
Explain the significance of HDL in reverse cholesterol transport.
HDL transports cholesterol from tissues back to the liver for excretion or recycling.
How does lipoprotein lipase (LPL) contribute to lipid metabolism?
LPL breaks down triglycerides in lipoproteins into free fatty acids and glycerol.
What happens to triglycerides and fatty acids in the smooth and rough ER during chylomicron formation?
The smooth ER reassembles monoglycerides and fatty acids into triglycerides, and the rough ER synthesizes Apo-protein B48.
What is the primary function of LDL in lipoprotein metabolism?
LDL distributes cholesterol to peripheral tissues and organs for hormone synthesis.
What is the clinical significance of imbalanced lipoprotein levels?
Imbalance can lead to conditions like atherosclerosis, particularly due to oxidized or glycated LDL.
What are the two primary pathways in lipoprotein metabolism?
Exogenous Pathway and Endogenous Pathway.
What are the primary components of VLDL synthesized by the liver?
VLDL contains triglycerides, cholesterol, phospholipids, and ApoB100.
How do chylomicrons enter the bloodstream?
Chylomicrons are absorbed into the lymphatic system via lacteals and eventually enter the bloodstream.
What enzymes are crucial in lipid metabolism aside from LPL?
Hepatic triglyceride lipase (HTGL) and cholesterol ester transfer protein (CETP).
How is LDL formed from VLDL?
LDL is formed from VLDL remnants (IDL) through further depletion of triglycerides by hepatic triglyceride lipase.
What is considered a healthy level of HDL for males and females?
40-50 mg/dL for males and 50-60 mg/dL for females, with higher levels being better.
What is the role of HDL in relation to chylomicrons?
HDL transfers ApoE and ApoC2 to chylomicrons; ApoC2 activates lipoprotein lipase (LPL) which breaks down triglycerides.
Where does the exogenous pathway of lipid metabolism begin?
In the small intestine.
What constitutes a healthy total serum cholesterol level?
<200 mg/dL.
What role do apolipoproteins play in lipid metabolism?
Apolipoproteins are essential for the structure and function of lipoproteins (e.g., ApoB48, ApoB100, ApoE, ApoC2, ApoA1).
What role does Cholecystokinin (CCK) play in lipid metabolism?
CCK stimulates the gallbladder to contract and release bile into the small intestine.
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