What hormone is primarily responsible for promoting the growth of bones and muscles?

The hormone that is primarily responsible for promoting the growth of bones and muscles is growth hormone. This hormone, produced by the anterior pituitary gland, plays a critical role in growth during childhood and adolescence, as well as in certain metabolic processes throughout life.

Growth hormone stimulates the growth of skeletal muscle and bone by promoting the production of insulin-like growth factor 1 (IGF-1), which has direct effects on these tissues. It enhances protein synthesis and increases the utilization of fat for energy, contributing to the overall anabolic (growth-promoting) state of the body. This is essential for normal physical development and muscle strength.

In contrast, insulin primarily regulates carbohydrate and fat metabolism rather than directly promoting growth. Thyroid hormones affect metabolism and body temperature regulation but are not the main hormones for stimulating growth in bones and muscles. Prolactin, while involved in lactation and certain aspects of reproductive health, does not play a significant role in promoting growth in skeletal or muscular tissues.