PITUITARY

(Pituitary, The master glands) – 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 bonny pocket just behind and above the nose.

The pituitary is not impressive to look at. It is only the size of a pee, and its weight is mere 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. Some jobs the pituitary delegates to other endocrine glands. For example the pituitary launches a hormonal message into the blood stream ordering the thyroid gland to produce and release three other hormones. These control metabolism, body heat and bone maintenance. The pituitary gland likewise commands the sex glands to produce the hormones that will bring about the physical changes of puberty. The master gland also instructs 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 on the mother’s breasts, when baby is born, mother is equipped to feed it.

While the pituitary is the overseer of other glands, it has its own overseer- the HYPOTHALAMUS. This is a cluster of nerve cells no larger than the tip of our thumb. It is located at the base of the brain and is connected to the pituitary. Its job is not only to supervise the work of the endocrine system but also to co-ordinate the work of the automatic nervous system.

Part of its work is to test the makeup and temperature of the blood. More blood gushes through the hypothalamus than any other part of the brain. If the blood is too cool, the hypothalamus sends instructions (via the pituitary and thyroid) for more THYROXINE, a hormone that boosts metabolism to produce heat to warm the blood.

Since the hypothalamus does its work automatically. We are usually unaware of its labors; yet, it has a day to day effect on our lives. Are we hungry? Our hypothalamus has detected too little glucose in our blood, it is telling us to eat. Are we thirsty? Our hypothalamus has decided that the salt level in our blood is a little too high. “Drink some water” it tells us.

The hypothalamus also monitors levels of calcium in the blood, without calcium our brain, muscles, and nerves would not work properly. When the level of blood calcium is too low, the hypothalamus withdrawing calcium from the bones, much as draw money from a bank. How is the calcium withdrawal made?

The hypothalamus sends a hormonal message to the pituitary. The pituitary launches its own command to the PARATHYROIDS located in the neck. The Parathyroid, in turn, secretes parathormone, which goes to the bones to request calcium for the blood stream. Once the hypothalamus sees that the calcium level is correct, it cancels orders for further withdrawals.

But what is the hypothalamus learns that there is too much calcium in blood? Once again messengers are sent to the “bone bank” but instead of making a withdrawal, they make a deposit. This is the procedure. The hypothalamus sends a message to its Chief Executive, (THE PITUITARY). The pituitary now issues a command to the thyroid. The thyroid, intern, sends out the hormone Calcitonin, which acts to transfer, excess calcium from the blood to the bones.

What a master piece of organization;

The hypothalamus controls the pituitary.

The pituitary directs the glands. And

The glands regulate the body.

And all of this is done by more than 30 different kinds of hormones that flow silently through our body to care for our most basic physical needs. Yet despite the complexity of all this, the endocrine system operates with stunning efficiency.