11.2 The pituitary gland
The pituitary gland weighs about half a gram and is located below the cerebrum. Despite its size, it plays a very important role in the regulation of the body's functions.
Many of the hormones secreted by the pituitary gland affect the body's functions, as well as the functions of other endocrine glands. In turn, it is regulated by the brain's hypothalamus, which secretes hormones that cause the pituitary gland to increase or decrease its own hormone production.
The growth hormone (somatotropin, HGH) secreted by the pituitary gland is one of the factors that influence an individual's growth together with the hormones secreted by the thyroid gland and gonads. The growth hormone regulates bone growth as well as the production of proteins, which is important for the functions of cells and tissues.
The human growth hormone (HGH) influences height.
If HGH is not secreted sufficiently during an individual's growth period, the person will gain a short stature. Conversely, the excessive secretion of HGH causes excessive growth. The reason for excessive hormone secretion is usually a tumour located either in the hypothalamus or elsewhere in the brain. Excessive secretion may also counteract the effects of insulin.
Excessive secretion in adulthood usually results in hypertrophy of the extremities of the body, such as the feet or palms. Unlike thyroxine secreted by the thyroid gland, HGH has no effect on mental growth.
| Hormone | Effects |
|---|---|
| thyrotropin (TSH) | thyroid function |
| follitropin (FSH or follicle stimulating hormone) | gonads: gametes production |
| lutropin (LH or lureinizing hormone) | gonads: testoterone |
| prolactin | secretion of milk |
| corticotropin | adrenal cortex |
| growth hormone (GH or somatropin) | in tissue metabolism and growth |
| Hormone | Effects |
|---|---|
| oxytocin | e.g. labor contractions and relaxation of the mammary glands |
| ADH (antidiuretic hormone) | concentrates urine by regulating water in the body |