What is the physiological function of insulin?

Insulin is a peptide hormone secreted by pancreatic beta cells within the endocrine system of the human body. Its main physiological functions include promoting glucose transport, inhibiting glycogen breakdown, promoting fat and protein synthesis, and stimulating glycogen synthesis, among others.

1. Promotes glucose transport: By activating glucose transporter proteins on the cell membrane, insulin increases glucose uptake by muscle and fat cells, thereby lowering blood glucose levels.

2. Inhibits glycogen breakdown: Insulin can inhibit glycogen breakdown and gluconeogenesis, thus reducing hepatic glucose output, which is another mechanism by which it lowers blood glucose levels.

3. Promotes fat and protein synthesis: Insulin also promotes the synthesis and storage of fat, reduces fat breakdown and oxidation, thereby decreasing free fatty acids in the blood and inhibiting the release of fatty acids.

4. Stimulates glycogen synthesis: In the liver and muscles, insulin promotes the conversion of glucose into glycogen for storage, thereby reducing blood glucose levels.

Therefore, insulin plays a role in maintaining stable blood glucose levels, energy metabolism, and fat distribution in the human body.