The pituitary gland is often referred to as the "master gland" of the body, since it regulates many activities of other endocrine glands. Located above the pituitary gland is the hypothalamus. The hypothalamus decides which hormones the pituitary should release by sending it either hormonal or electrical messages.

In response to hormonal messages from the hypothalamus, the pituitary gland releases the following hormones:

• GH (growth hormone) – increases size of muscle and bone
• THS (thyroid stimulating hormone) – stimulates the thyroid gland to release T3 and T4 to stimulate metabolism in other cells throughout the body
• FSH (follicle stimulating hormone) – stimulates ovarian follicle production in women; stimulates sperm production in men
• LH (luteinizing hormone) – stimulates ovaries to produce estrogen in women; stimulates sperm production in men
• Prolactin – stimulates breast tissue in nursing mothers to produce milk
• ACTH (adrenocorticotropic hormone) - causes the adrenal glands to produce important substances that have properties similar to steroids

In response to electrical messages from the hypothalamus, the pituitary gland releases the following hormones:

• ADH (antidiuretic hormone) - stimulates the kidneys to reabsorb fluid and produce less urine
• Oxytocin – initiates labor, uterine contractions and milk ejection in mothers