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GI I Exam 2 Cholesterol metabolism & lipoprotein transport
11 questions
16
Medical
Graduate
01/21/2011

Additional Medical Flashcards

 


 

Cards

Term
Describe the composition and respective physiological roles of the basic lipoprotein classes
Definition
Term
Describe the origin (genesis) and catabolism of each major lipoprotein class and their respective roles as CHD risk indicators
Definition
Term
Describe the regulation of cholesterol biosynthesis via HMG-CoA reductase.
Definition
Term
Describe the low density lipoprotein pathway and its relevance to atherosclerosis and the risk of coronary heart disease in detail
Definition
Term
Describe the mechanism of action of bile acid sequestrants and statin drugs
Definition
Term
How oxidized LDL contributes to thrombogenesis
Definition
Oxidized LDL activates macrophages, stimulates TF expression, which leads to hypercoagulability (accelerated thrombosis)
Term
Dyslipidemia
Definition
Key risk factor for atherosclerosis

Abnormal pattern developing in the amount or distribution of blood lipids (TG and cholesterol) and their impact on atherosclerosis
Term

Chylomicrons

 

- major core lipid

- metabolic function

- synthesis/metabolism

Definition

Triglycerides

 

transport of dietary triglycerides to adipose tissue and muscle tissue

 

Nascent TAG-rich chylomicrons (CM) are produced in intestinal mucosal cells, primarily from dietary lipids.

 

When CM reaches plasma, it is modified by receiving apolipoproteins from circulating HDL. Apo C-II activates lipoprotein lipase, which hydrolyzes TAG in the CM to glycerol and FA. (Lipoprotein lipase synthesis & transfer is stimulated by insulin/fed state.)

 

*Patients with a deficiency in lipoprotein lipase or apoC-II show a dramatic accumulation of chylomicrons in the plasma (hypertriacylglycerolemia), even in the fasted state*

 

Cholesteryl ester-rich CM remnants bind to liver where they're endocytosed.

 

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Term

VLDL

 

 

- major core lipid

- metabolic function

- synthesis/metabolism

Definition

Triglycerides

 

transport of endogenously synthesized (hepatic) triglycerides to adipose tissue and muscle tissue

 

Liver secretes nascent TAG-rich VLDL containing apo B100.

 

In plasma, VLDL receives apoproteins from HDL, apo C-II activates lipoprotein lipase which degrades TAG in VLDL in tissues (e.g. adipose).

 

*Cholesteryl ester transfer protein (CETP) facilitates the transfer of TAG from VLDL to HDL in exchange for cholesteryl esters from HDL to VLDL.

VLDL  --TAG--> HDL

VLDL  <--CE--   HDL

 

VLDL is converted in plasma to LDL

 

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Term

LDL

 

- major core lipid

- metabolic function

- synthesis/metabolism

Definition

Cholesteryl esters (CE)

 

transport of cholesterol to peripheral cells and to liver cells - atherogenic

 

LDL binds to B100 receptors on tissues, where they are endocytosed. Apo B-100 is located on the surface of LDL

 

*LDL receptor deficiency -> high cholesterol (familial hypercholesterolemia/type II hyperlipidemia)*

 

Lysosome is degraded, AA/FA/cholesterol is used by cell.

 

Oversupply of cholesterol inhibits HMG CoA reductase (de novo cholesterol synth d/c) and synthesis of new LDL receptor protein.

Term

HDL

 

- major core lipid

- metabolic function

- synthesis/metabolism

Definition

Cholesteryl esters (CE)

 

transport of cholesterol from peripheral tissues to the liver - anti-atherogenic

 

Formed in blood by addition of lipid to apo A-1; picks up cholesterol from other lipoproteins or tissues, then LCAT forms CE in HDL to create mature serum HDL.

 

Functions of HDL:

 

- reservoir of apolipoproteins (inc. apo C-II, -> VLDL and chylomicrons, activate lipoprotein lipase)

 

- uptake of unesterified cholesterol

 

- esterification of cholesterol (by PCAT; CTEP moves some of the cholesteryl esters from HDL to VLDL in exchange for TAG)

 

- *reverse cholesterol transport* (peripheral cells -> HDL -> liver for bile acid synthesis or disposal via bile)

Term

Apolipoproteins & function

 

*B-100, C-II*

Definition
[image]
Term
Mechanism of triglyceride transport and metabolism: sequence of events
Definition
1. secretion of chylomicrons (Small intestine)

2. role of lipoprotein lipase, hepatic lipase (capillary endothelium)

3. generation (blood) and receptor uptake of remnant particles (liver)

4. biosynthesis of VLDL ( Liver)

5. metabolism of VLDL: receptor uptake (liver) and metabolism of IDL (blood)

6. generation of LDL (blood)
Term

Cholesterol biosynthesis

 

(pathway, image)

Definition
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Term
Bile acid sequestrants, statins
Definition
[image]
Term
Effect of CETP inhibition on plasma cholesterol transport
Definition
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