The pituitary is a small gland attached to the base of the brain (behind the nose) in an area called the pituitary fossa or sella turcica. 

The pituitary is a small gland attached to the base of the brain (behind the nose) in an area called the pituitary fossa or sella turcica. The pituitary is often called the "master gland" because it controls the secretion of most of the hormones in the body. A normal pituitary gland weighs less than one gram and is about the size and shape of a kidney bean.

The function of the pituitary can be compared to that of a household thermostat. The thermostat constantly measures the temperature in the house and sends signals to the heater to turn it on or off to maintain a steady, comfortable temperature. The pituitary constantly monitors bodily functions and sends signals to remote organs and glands to monitor their function and maintain the appropriate environment. The ideal "thermostat" setting for a body depends on many factors including level of activity, gender, body composition, etc.

The pituitary is responsible for controlling and coordinating the following:

  • Growth and development

  • Organ function (kidneys, breasts and uterus)

  • Gland function (thyroid, gonads and adrenal glands

Pituitary Anatomy and Functions

The pituitary is divided into distinct sections: the anterior pituitary gland and the posterior pituitary gland. Each part contains unique cells and releases different hormones that are responsible for specific control duties.

Brain Pituitary

The anterior pituitary is formed from the same tissue as the pharynx. The posterior pituitary is formed from an out-pouching of the brain and is actually an extension of the hypothalamus, a region of the brain that is connected to the pituitary gland and controls its function. The hypothalamus and pituitary together comprise the neuroendocrine system.

The anterior pituitary accounts for about 80 percent of the pituitary gland size and is composed of the anterior lobe and the intermediate zone. The anterior lobe is responsible for producing the majority of the signaling hormones released into the blood stream. The posterior pituitary gland develops very early in life and does not produce any hormones on its own. However, it does contain the nerve endings of brain cells (neurons) that arise from the hypothalamus. These neurons produce the hormones vasopressin and oxytocin which are transported down the pituitary stalk into the posterior pituitary. They are stored for later release into the bloodstream.

The pituitary and hypothalamus work together to regulate the daily functions of the body as well as play an essential role in growth, development and reproduction. The hypothalamus secretes two types of hormones (releasing hormones and inhibiting hormones) that control secretion of other hormones from the anterior pituitary. The pituitary gland performs its key functions by releasing several signaling hormones that consequently control the activities of other organs.

The pituitary produces the following hormones:

  • Growth hormone (GH) — This is the principal hormone that regulates metabolism and growth.

  • Luteinizing hormone (LH) and Follicle-stimulating hormone (FSH) — These hormones control the production of sex hormones (estrogen and testosterone) and are important in regulating menstruation in women.

  • Melanocyte-stimulating hormone (MSH) — MSH regulates the production of melanin, a dark pigment, through melanocytes in the skin. Increased melanin production produces pigmentation or tanning of the skin. Some conditions causing excessive production of MSH may lead to darkening of the skin.

  • Prolactin (PRL) — This hormone stimulates secretion of breast milk.

  • Thyroid-stimulating hormone (TSH) - TSH stimulates the thyroid gland to release thyroid hormones. Thyroid hormones control the basal metabolic rate and play an important role in growth and maturation. Thyroid hormones affect almost every organ in the body.

  • Vasopressin/ Antidiuretic hormone (ADH) — This hormone promotes water retention.

Tumors that occur in the region of the pituitary gland:

Reproduced by permission of the copyright owner. American Association of Neurological Surgeons, 5550 Meadowbrook Dr., Rolling Meadows, IL  60008. Further reproduction prohibited without permission, 2016.

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