Tag: parts of the brain

The male sex hormone testosterone is produced by Leydig cells. These cells are located in the connective (interstitial) tissue, that holds the tubules together within each lobule. The tissue becomes markedly active at puberty under the influence of the interstitial-cell-stimulating hormone of the anterior lobe of the pituitary gland.

Prolactin is produced both in the anterior pituitary gland. It stimulates the mammary glands to produce milk (lactation); increased serum concentrations of prolactin during pregnancy cause enlargement of the mammary glands of the breasts and prepare for the production of milk. 

In men, testosterone plays a key role in the development of male reproductive tissues, such as the testis and prostate as well as promoting secondary sexual characteristics, such as increased muscle, bone mass, and the growth of body hair.

In women, relaxin is secreted into the circulation by the corpus luteum in the ovary. During pregnancy it is also released from the placenta, the membranes, which surround the foetus, and the lining of the uterus. During pregnancy, relaxin levels are at their highest in the first trimester. At this time it is believed to promote implantation of the developing foetus into the wall of the uterus and the growth of the placenta. Towards the end of pregnancy, relaxin promotes rupture of the membranes surrounding the foetus and the growth, opening and softening of the cervix and vagina to aid the process of childbirth. Relaxin can relax the ligaments at the front of the cervix to ease delivery of the baby. 

Gonadotropins are secreted from the anterior pituitary gland and act on the gonads (i.e., the ovaries or testes). Gonadotrophs secrete two primary gonadotropins: luteinizing hormone (LH) and follicle-stimulating hormone (FSH). 

Prolactin was discovered in non-human animals around 1930 by Oscar Riddle. It promotes milk production in the female. It is also known as a lactogenic hormone. It is produced by the pituitary gland.

Androgens include the male hormones testosterone and androsterone and promote development of male sex characteristics. The androgens promote the secondary sex characteristics of muscle growth, lowered voice range, the Adam's apple, and increased body hair.

Glucagon's role in the body is to prevent blood glucose levels dropping too low. It acts on the liver and stimulates the conversion of stored glycogen (stored in the liver) to glucose, which can be released into the bloodstream. This process is called as glycogenolysis.

Gynaecomastia is enlargement of the male breast tissue. Oestrogen stimulates breast tissue growth, while androgens inhibit it. The important factor is the ratio of active androgens to oestrogens. The ratio can be altered as a result of reduced testosterone production/action or enhanced oestrogen production/action or both.