Lowering LDL Flashcards
What is the function of cholesterol in the body?
Cholesterol is the precursor for steroid hormones and bile acids. It is also essential for the structural integrity of cell membranes.
What is the structure and function of Lipoproteins?
Lipoproteins are made up of a central lipid core (containing insoluble TG and cholesterol esters) and a hydrophilic coat made up of phospholipids, apolipoproteins and free cholesterol.
Their function is to transport cholesterols and triglycerides through the blood as they are insoluble.
Function of Chylomicrons
Chylomicrons absorb dietary triglycerides and cholesterol and transport them in the blood to peripheral tissues and finally to the liver
Function of vLDL
vLDL transports TG and cholesterol around the body to peripheral tissues. TG-rich vLDL containing ApoB-100 is secreted from the liver.
Function of LDL
LDL is formed after serial lipolysis of vLDL and carries cholesterol esters to peripheral tissues. It only contains ApoB-100.
Function of HDL
HDL carries cholesterol from peripheral tissues back to the liver for secretion into bile and feces.
How do Statins work?
Statins are HMG-CoA Reductase Inhibitors, meaning they inhibit the rate limiting step of cholesterol synthesis, in which HMG-CoA is converted to Mevalonic Acid.
More specifically, statins are competitive, reversible inhibitors which mimic HMG-CoA, the substrate for HMG-CoA Reductase. They bind to the active site of the enzyme and therefore block the natural substrate from entering the enzyme and being converted. Their affinity towards HMG-CoA is >10000 greater than that of HMG-CoA.
What are the therapeutic effects of statins?
Statins decrease hepatic cholesterol synthesis. This leads to the upregulation of LDL receptor synthesis and thus increased LDL cholesterol clearance from the plasma, subsequently leading to decreased plasma LDL levels.
