Cholesterol Metabolism

These flashcards cover key concepts related to cholesterol metabolism, including biosynthesis, functions, regulation, and transport.

Cholesterol comes from two sources:

diet and genetics

HMG CoA reductase is the key regulator of __ biosynthesis.

Cholesterol

Cholesterol plays a role in regulating __ fluidity.

Membrane

Vitamin D3 is synthesized from 7-dehydrocholesterol in the skin and is activated in the and .

Liver and Kidney

Calcitriol, the active form of vitamin D3, regulates calcium, phosphorus, and __ levels in the body.

Magnesium

Cholesterol is a precursor for __ hormone synthesis.

Steroid

Bile salts are synthesized in the and stored in the .

Liver and gall bladder

Bile salts emulsify TAGs in the __ for digestion.

Intestine

Cholesterol must be transported by __ particles due to its low solubility.

Lipoprotein

LDLs deliver cholesterol from the liver to __ with large cholesterol needs.

Tissues

HDLs reverse transport cholesterol from tissues back to the __.

Liver

The transcription factor SREBP activates HMG CoA reductase transcription when cholesterol levels are __.

Low

High levels of cholesterol lead to the __ of HMG CoA reductase, inhibiting cholesterol synthesis.

Degradation

Phosphorylation of HMG CoA reductase is stimulated by __ signaling.

Insulin

Cholesterol esters are primarily found in the core of __.

Lipoproteins

Chylomicrons transport dietary fat from the __ to tissues.

Intestine

VLDLs transport endogenous fat from the __ to tissues.

Liver

LDL receptor-mediated endocytosis involves three steps: binding, __, and hydrolysis.

Internalization

ApoB-100 is the structural apolipoprotein of __.

LDL

Familial hypercholesterolemia is caused by a defect in __ receptor synthesis.

LDL

Statins inhibit __, which is the rate-limiting enzyme in cholesterol biosynthesis.

HMG-CoA reductase

Ezetimibe is a drug that inhibits dietary absorption of __.

Cholesterol

Cholesterol levels are classified as low (

Low

Hyperlipoproteinemias are classified by the excess __ present in the blood.

Lipoproteins

Dietary lipids are emulsified by bile salts in the __ intestine before being transported by chylomicrons.

Small

Lipids in the bloodstream are transported by five major classes of lipoproteins: chylomicrons, VLDL, IDL, LDL, and __.

HDL