Final answer:
Insulin released by the pancreas after meals increases glucose uptake by muscle and fat cells and promotes the storage of glucose as glycogen in the liver and muscles. It does not initiate the breakdown of glycogen or fat tissue, which is a common misconception.
Step-by-step explanation:
Role of Insulin in Glucose Regulation
When insulin is released into the bloodstream, it has several effects on the body's metabolism of glucose. One of its primary roles is to counteract high levels of glucose in the blood. After a meal, blood glucose levels become elevated, which stimulates the beta cells in the pancreas to release insulin. This hormone then promotes the uptake of glucose by muscle and fat cells, effectively reducing blood glucose concentrations. Additionally, insulin facilitates the conversion of glucose into glycogen within the liver and muscle cells, where it is stored for future energy needs. If blood glucose levels fall too low, the alpha cells of the pancreas release glucagon, which prompts the liver to break down glycogen back into glucose, releasing it into the bloodstream to normalize glucose levels.
Contrary to initiating glycogen breakdown, insulin actually inhibits the breakdown of glycogen in the liver. It also does not promote the breakdown of fat in fat tissue; instead, it aids in fat storage. Therefore, the correct function of insulin is to increase glucose uptake by muscle and fat cells and to promote the conversion of glucose into glycogen within the liver and muscle.