Pituitary​—The Master Gland

The overseer of the endocrine system is the pituitary, a small, reddish-​gray organ that is attached to the brain by a slender stalk and that lies in a bony pocket just behind and above the nose.

The pituitary is not impressive to look at. It is only the size of a pea, and it weighs a mere 0.02 ounce [0.6 gm]. But even though the pituitary is small, its responsibility is immense. It has been called the master gland, the conductor of the endocrine orchestra. It is like a business executive whose office is a flurry of activity, with messages coming from and going to many departments.

Some jobs the pituitary delegates to other endocrine glands. For example, the pituitary launches a hormonal message into the bloodstream ordering the thyroid gland to produce and release three other hormones. These control metabolism, body heat, and bone maintenance. The pituitary likewise commands the sex glands to produce the hormones that will bring about the physical changes of puberty. The master gland can also instruct the adrenals to manufacture hormones that maintain blood pressure and salt balance in the body.

At times, though, the pituitary cares for matters directly, sending out hormonal messages that influence the growth of our bones and muscles. Its hormones even control how tall we will be.

The pituitary further plays a big role in delivering babies. To assist a woman in labor, the pituitary sends out oxytocin, a hormone that stimulates contractions of the womb. When the baby’s head reaches the birth canal, the brain sends a message to the pituitary requesting an extra supply of oxytocin to help with the final phase of delivery. All along, hormones from the pituitary have been stimulating the production of milk in the mother’s breasts. When baby is born, mother is equipped to feed it.

The Master Gland’s Master

While the pituitary is the overseer of other glands, it has its own overseer​—the hypothalamus.

The hypothalamus sends a hormonal message to the pituitary. The pituitary launches its own command to the parathyroids, located in the neck.

The hypothalamus sends a message to its chief executive, the pituitary. The pituitary now issues a command to the thyroid.

Pituitary Gland

This pea-​sized organ is attached to the brain by a slender stalk and lies just above and behind the nose. The pituitary is supervisor of the other glands, sending out chemical messages to the thyroid, adrenal, and sex glands, as well as to other glands having endocrine functions. It is the main controller of height and influences the growth of bones and muscles. It also stimulates the production of milk by the breasts of a nursing mother.