As we progress from youth to senior, the most important
transforming factors are hormones. Both men and women have hormonal control occurring in the brain, and
more specifically in the hypothalamus. The hypothalamus detects that levels
of the hormone testosterone are inadequate. It sends a message to the
pituitary gland via gonadotropin-releasing hormone (GnRH). The pituitary
receives the message of low testosterone from GnRH and releases
luteinizing hormone (LH) and follicle stimulating hormone (FSH) at hourly
intervals. The FSH stimulates the Leydig cells in the testes (testicles) to
produce more testosterone. Once levels of testosterone are adequate, the
hypothalamus will stop sending GnRH to the pituitary. The process is called
a feedback system.
