Testosterone is a hormone that is naturally produced in the human body. Though the chemical is similar for men and women, the levels of testosterone vary between the two. On average, men produce 6 to 8 mg of the hormone daily. Women make about 12 times less than men every day. The endocrine system regulates testosterone production, specifically by the hypothalamus and pituitary gland.
Hormones are chemicals of the endocrine system that travel in the bloodstream to facilitate cell communication. Testosterone is classified as a steroid hormone because it is released to all cells. These hormones are important during puberty in the development of secondary sex traits, such as the growth of pubic hair.
Gonadotrophins stimulate the testes in males and ovaries in females for reproduction. Starting in the brain, the hypothalamus releases hormones to trigger the secretion of luteinizing hormones, or LH. In males, LH is received in the testes and signals Leydig cells to produce testosterone. Ovaries produce most of the testosterone hormones in the female body.
The classical negative feedback cycle regulates the amount of testosterone in the body. When there is a high level of testosterone present in the bloodstream, the hypothalamus lowers the amount of gonadotrophins released. This system is similar to how a thermostat helps regulate the temperature in a room.
Effects on the Body
Testosterone helps the body mature and prepare for sexual reproduction. In males, testosterone is responsible for lowering their voices, facial hair growth, sperm production and building muscle mass. In females, testosterone supports muscle and bone strength.
People get tested for testosterone levels when there are symptoms of abnormal male hormone production. According to MedlinePlus, a simple blood test is used as a diagnostic to identify early or late puberty in boys and impotence or infertility in men. Women are usually tested when there is excessive hair growth, male body characteristics or an irregular menstrual cycle.
- National Institute on Aging: Frequently Asked Questions About Testosterone and the IOM Report
- Kimball's Biology Pages: The Hormones of the Human
- Kimball's Biology Pages: Hormones of the Reproductive System
- Discovery Health: Estrogen and Testosterone Hormones
- Colorado State University: Gonadotropins: Luteinizing and Follicle Stimulating Hormones