Describe how fats are metabolized. Identify the difference between LDL and HDL and how each contributes to coronary artery disease.
The correct answer and explanation is:
Fats, or lipids, are metabolized in the body through a series of steps that allow them to be used for energy or stored for later use. After ingestion, dietary fats are broken down into smaller molecules, primarily fatty acids and glycerol, by digestive enzymes in the small intestine. These molecules are then absorbed by intestinal cells, where they are reassembled into triglycerides. The triglycerides are packaged into chylomicrons, which are lipoprotein particles that enter the lymphatic system and eventually the bloodstream.
Once in the bloodstream, these lipoproteins transport triglycerides to various tissues. Muscle cells use fatty acids for energy, while fat cells store excess triglycerides. In the liver, fats are further processed into very-low-density lipoproteins (VLDL), which are then released into the bloodstream to deliver fat to tissues. As VLDL particles circulate, they lose triglycerides, becoming low-density lipoproteins (LDL), which are primarily responsible for transporting cholesterol to cells.
There are two primary types of cholesterol-carrying lipoproteins: low-density lipoprotein (LDL) and high-density lipoprotein (HDL). LDL is often referred to as “bad cholesterol” because it can deposit cholesterol in the walls of arteries, forming plaques that narrow and harden the arteries. This condition, known as atherosclerosis, increases the risk of coronary artery disease (CAD), as it can restrict blood flow to the heart and increase the risk of heart attacks.
HDL, on the other hand, is considered “good cholesterol” because it helps remove excess cholesterol from the bloodstream by transporting it back to the liver for processing and excretion. Higher levels of HDL are protective against CAD, as they help reduce cholesterol buildup in the arteries.
In summary, LDL contributes to coronary artery disease by promoting plaque buildup in artery walls, while HDL helps protect against this process by removing cholesterol from the bloodstream.