PHYSIOLOGY
AND PATHOPHYSIOLOGY OF DIABETES
Insulin
is secreted by beta cells, which are one of four types of cells in the islets
of Langerhans in the pancreas. Insulin is an anabolic, or storage, hormone.
When a person eats a meal, insulin secre-tion increases and moves glucose from
the blood into muscle, liver, and fat cells. In those cells, insulin:
•
Transports and metabolizes glucose for energy
•
Stimulates storage of glucose in the liver and
muscle (in the form of glycogen)
•
Signals the liver to stop the release of glucose
•
Enhances storage of dietary fat in adipose tissue
•
Accelerates transport of amino acids (derived from
dietary protein) into cells
Insulin
also inhibits the breakdown of stored glucose, protein, and fat.
During fasting periods (between meals and overnight), the pancreas continuously releases a small amount of insulin (basalinsulin);
another pancreatic hormone called glucagon (secreted by the alpha cells of the
islets of Langerhans) is released when blood glucose levels decrease and
stimulate the liver to release stored glucose. The insulin and the glucagon
together maintain a constant level of glucose in the blood by stimulating the
release of glucose from the liver.Initially, the liver produces glucose through
the breakdown of glycogen (glycogenolysis). After 8 to 12 hours without food,
the liver forms glucose from the breakdown of noncarbohydrate substances,
including amino acids (gluconeogenesis).
Related Topics
Privacy Policy, Terms and Conditions, DMCA Policy and Compliant
Copyright © 2018-2024 BrainKart.com; All Rights Reserved. Developed by Therithal info, Chennai.