In physiology, FA commonly stands for Free Fatty Acids.
Free fatty acids are a crucial energy source for many tissues in the body. They are taken up by cells, primarily via transport proteins like CD36 and FATP family receptors, and can undergo various metabolic processes depending on the body's energy needs.
Role of Free Fatty Acids (FA)
- Energy Source: FA are a primary fuel source, particularly during periods of fasting or prolonged exercise. They are broken down through beta-oxidation to produce ATP, the cell's energy currency.
- Lipid Droplet Formation: FA can be stored as triglycerides in lipid droplets within cells. This is a mechanism for long-term energy storage.
- VLDL Formation: In the liver, FA can be incorporated into very-low-density lipoproteins (VLDL), which transport triglycerides to other tissues.
- Cellular Signaling: Beyond their role as an energy source, FA can also act as signaling molecules, influencing gene expression and cellular function.
FA Uptake
FA are transported from the plasma into cells through specific proteins. Examples include:
- CD36: A transmembrane glycoprotein that facilitates FA uptake in various tissues.
- FATP Family Receptors: A family of fatty acid transport proteins that also play a role in FA uptake.
Metabolic Fates of FA
Once inside the cell, FA can undergo several different fates:
- β-oxidation: The breakdown of FA to produce energy (ATP).
- Lipid Droplet Formation: Storage of FA as triglycerides.
- VLDL Formation: Packaging of FA into lipoproteins for transport to other tissues (primarily in the liver).
In summary, free fatty acids are a vital energy source and signaling molecule in physiology. Their uptake and metabolism are tightly regulated to meet the body's energy demands and maintain metabolic homeostasis.
