Final answer:
Male growth and development are chiefly regulated by the hormone testosterone, which leads to secondary sexual characteristics and spermatogenesis. The onset of puberty is triggered by the hypothalamus and pituitary gland. Individual growth rates can have psychological and social impacts on teenagers.
Step-by-step explanation:
Internal factors that influence male growth and development are primarily centered around hormones, particularly testosterone. Testosterone, which is secreted by the testes, is crucial for the development of secondary sexual characteristics. These characteristics include a deepening of the voice, growth of facial, axillary, and pubic hair, and an increase in muscle bulk, all hallmarks of male puberty. In addition to these external changes, testosterone stimulates spermatogenesis, the production of sperm, which is essential for male fertility.
Puberty is initiated when the hypothalamus signals the pituitary gland to release luteinizing hormone (LH), prompting the testes to produce testosterone. This surge in hormones leads to rapid body growth and the maturation of reproductive organs. Environmental factors can also have an influence; for instance, a fetus receiving inadequate nutrition or exposure to infections may have different developmental outcomes compared to a fetus provided with optimal conditions.
Growth rates can vary among teenagers, which can affect their social experiences and psychological wellbeing. For example, early maturing boys often tend to have more confidence and popularity but also face risks for earlier involvement in substance abuse and sexual activity. On the other hand, boys who mature later may experience self-consciousness and higher risks for depression.