THE ADRENAL GLANDS, THE PITUITARY GLAND, & THE PARATHYROID GLANDS
The parathyroid glands
These tiny glands, about the size of a very small pea, are embedded near the base of the thyroid, usually in clusters of four. They control the excretion in urine of the calcium and phosphorus that are derived from lime salts and that make the bones hard.
In parathyroid deficiency, the calcium regulation is disturbed, and the muscles become subjected to spasms. The administration of the parathyroid hormone, certain synthetic compounds with similar actions, or a potent vitamin D preparation will keep the calcium output normal and stop the spasms. Taking calcium is also extremely helpful.
The adrenal glands
These two glands fit like small cups, one on the top of each of the two kidneys. Each adrenal gland is divided into two parts: the cortex, or outer portion, and the medulla, or central section. The cortex, essential to life, secretes about 38 hormones and regulates many metabolic processes.
The two main functions of the hormones of the adrenal cortex are: (1) to control the salt and water content of the body; (2) to control sugar and protein metabolism, acting the opposite to insulin.
In addition, the cortex secretes sex hormones, mainly androgens similar to those produced by the testicles.
Atrophy or underfunctioning of the adrenal cortex produces Addison’s disease The medulla of the adrenal gland produces the hormone called adrenaline or epinephrine. The output of this hormone is immediately stepped up when you become angry, fearful, or excited. This produces chemical changes that prepare the body for action. The pituitary hormone ACTH (adrenocorticotropin) stimulates secretion of hormones by the normal adrenal glands. Cortisone, an adrenal hormone preparation, can replenish the body’s supply when the adrenal glands are diseased. Administration of these hormones may bring about favourable results in the treatment of many other diseases, including rheumatic fever, arthritis, and asthma.
The pituitary gland
This gland is located at the base of the brain. It is about the size of a pea and consists chiefly of an anterior lobe and a posterior lobe.
The most important function of the pituitary is to stimulate, regulate, and co-ordinate the functions of the other endocrine glands. For this reason it is called the master gland.
Diseases of the pituitary gland fortunately are quite rare. Too little pituitary secretion causes certain types of dwarfism, while too much stimulates the body to grow to gigantic proportions. Pituitary tumours may press on the optic nerves and cause headaches and loss of vision.
There is no effective replacement for every pituitary hormone, but treatment with cortisone derivative and thyroid- and sex-hormone extracts is frequently successful.
They help the growth of certain plants on which all other plants and animals depend. In fact, life without bacteria would not be possible.
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