Library · Physiology
Lipid metabolism
Make it clearer
Fats have a logistics problem: neither cholesterol nor triglycerides mix with water, and plasma, the liquid part of blood, is water. To move, they have to be packed inside particles called lipoproteins. They are trucks that wrap the cargo so water will not repel it.
There is more than one model of truck. There are chylomicrons, VLDL, IDL, LDL and HDL, and each one handles a different phase of transport.
Unloading happens in the body's smallest vessels, the capillaries of fat tissue and skeletal muscle. There an enzyme, lipoprotein lipase, breaks down the chylomicron's triglyceride core.
And glucagon, which rises during fasting, or epinephrine, which rises with exercise, switches on other lipases that release fatty acids, and those acids can then be burned in the Krebs cycle.
In brief
Cholesterol and triglycerides are nonpolar and travel through plasma with the help of lipoprotein particles.
Trucks that wrap the cargo so water will not repel it.
Chylomicrons, VLDL, IDL, LDL and HDL are those lipoproteins, and each one works in a different phase of transport.
In the capillaries of fat and skeletal muscle, lipoprotein lipase breaks down the chylomicron's triglyceride core.
Glucagon during fasting or epinephrine during exercise activates lipases that release fatty acids, which can then be burned in the Krebs cycle.
Sources (1)
- National Center for Biotechnology Information, StatPearls PublishingBiochemistry, Lipid Metabolism, StatPearlsPublished
This page explains the topic in general terms; it does not tell anyone what treatment to follow.
Updated