Picture of Pituitary Gland

The pituitary gland is a small gland in the brain. It is known as the master gland because the hormones it produces affect the production of many other hormones and functions in the body. The pituitary gland consists of anterior and posterior portions. Hormones produced by the anterior pituitary gland affect adrenocortical function, sexual development, growth, pigmentation of the skin, and thyroid function. If the anterior pituitary under functions, it results in retarded growth and decreased function of all other glands controlled by this part of the pituitary gland except for the parathyroid glands. When the anterious pituitary over functions, excess growth, or acromegaly, results.
The posterior pituitary gland is the back part of the pituitary. It secretes antidiuretic hormone (ADH) which affects water retention in the body and oxytoxin, which facilitates bonding and uterine contractions. A lack of ADH causes diabetes insipidus, which leads to excess urination and potentially dehydration.
Text Reference: National Cancer Institute SEER Training Modules: "Pituitary & Pineal Glands"