Final answer:
Insulin facilitates glucose uptake and utilization for energy, stimulates the liver to store glucose as glycogen, and inhibits gluconeogenesis to regulate blood glucose levels. Its main target cells include muscle, liver, and adipose tissue cells.
Step-by-step explanation:
Insulin, a critical hormone for regulating blood glucose levels, has several physiological actions:
- Glucose Uptake and Utilization: Insulin triggers body cells to take up glucose from the blood, enhancing its utilization for cellular respiration and energy (ATP) production.
- Glycogen Synthesis: The hormone stimulates the liver to convert excess glucose into glycogen for storage and inhibits mechanisms that break down glycogen back into glucose.
- Inhibition of Gluconeogenesis: Insulin inhibits enzymes involved in gluconeogenesis, the metabolic pathway that generates glucose from non-carbohydrate substrates.
The target cells for insulin action are primarily muscle, liver, and adipose tissue, although nearly all body cells rely on insulin for glucose uptake, with some exceptions like brain and red blood cells.