Which cholesterol is designated as “Good Cholesterol”?
**Core Concept**
High-density lipoprotein (HDL) is known as "good cholesterol" due to its role in removing excess cholesterol from the bloodstream and transporting it to the liver for excretion. HDL cholesterol plays a crucial part in maintaining cardiovascular health by reducing the risk of atherosclerosis and coronary artery disease.
**Why the Correct Answer is Right**
The correct answer is HDL because it has a high protein content compared to other lipoproteins, allowing it to bind and remove excess cholesterol from peripheral tissues and transport it to the liver for excretion. This process is facilitated by the enzyme cholesterol ester transfer protein (CETP), which facilitates the exchange of cholesterol esters between HDL and low-density lipoprotein (LDL). The apolipoprotein A1 (apoA1) is a key component of HDL, which helps in the activation of lecithin-cholesterol acyltransferase (LCAT) and the formation of cholesterol esters.
**Why Each Wrong Option is Incorrect**
* **Option A:** LDL is known as "bad cholesterol" because it transports cholesterol to peripheral tissues, contributing to the development of atherosclerosis.
* **Option B:** VLDL (Very Low-Density Lipoprotein) is a type of lipoprotein that transports endogenous triglycerides, cholesterol, and other lipids from the liver to peripheral tissues.
* **Option D:** Chylomicrons are large lipoproteins that transport dietary triglycerides from the small intestine to the liver and peripheral tissues.
**Clinical Pearl / High-Yield Fact**
Remember that HDL is inversely related to the risk of cardiovascular disease: higher levels of HDL are associated with a lower risk of atherosclerotic cardiovascular disease.
**Correct Answer: C. HDL**