The pituitary is the master controller of the endocrinal system, though it is in turn controlled by the brain via the hypothalamus. It is a small pea-sized gland located near the top of the spine in the brain. It only weighs half a gram, but it exercises a vast influence on all the processes of the body. It regulates the production and secretion of the hormones produced by the glands. Without the sensitive control of the pituitary, the hormonal secretion of the other glands would create havoc in the body.
The pituitary gland produces a number of different hormones in small quantities. Some of these act directly on the body, but most of them trigger the functions of the other glands. In this way, the pituitary has widespread influences on almost everything that occurs within the body.
Somatotrophic hormone (STH) promotes body growth and the ability to resist disease. Without this substance, we would easily die from even the mildest infection, for it mobilizes the white blood cells and antibodies to protect the body.
Adrenocorticotrophie hormone (ACTH) directs and mobilizes the function of the adrenal glands. When the brain receives sensory nerve impulses from the outside world which require quick or emergency response from the body, it stimulates the sympathetic nervous system and the pituitary, which in turn activates the adrenal glands; the adrenal glands secrete adrenaline which prepares the whole body for rapid reactions and actions. The entire process occurs very rapidly. ACTH also stimulates the secretion of other important hormones in the adrenal glands, including the glucocorticoids which act on the metabolism of food, and on the sex hormones.
The pituitary secretes a hormone called thyrotrophin which activates and controls the functioning of the thyroid gland. The thyroid performs a multitude of functions and if it is not functioning correctly then the whole body suffers drastically.
Pituitrin (also called pitressin) is concerned with the reabsorption of water in the kidneys and raising blood pressure.
Various sex hormones are secreted directly from the pituitary. The most important are the follicle stimulating hormone (FSH) and the luteinizing hormone (LH). FSH acts upon the follicle, the structure in the ovary in which the female egg develops. It causes rapid maturation of many follicles, so that the ovary enlarges to accommodate them. FSH also stimulates the hormone estrogen (estrin) which prepares the womb for growth of a baby (embryo). In men, FSH stimulates the production of sperm (spermatogenesis). Luteinizing hormone is associated with the monthly cycle of women. It also stimulates the production of another female hormone called progesterone (progestin) which is also concerned with preparing the body for the growth of a baby. In males, LH stimulates the production of the male sex hormone testerone, which specifically produces male characteristics in the body, such as hair growth, powerful muscles, deep voice and so forth. The pituitary also produces various other sex hormones, such as lactogen andpitocin which have other specific duties to perform.
The pituitary secretes a hormone called diabetogenic hormone, which has a direct influence on the liver and the production of insulin in the pancreas. This hormone is very important with regard to the understanding of diabetes. It is usually believed that the cause of diabetes is malfunctioning of the islets of Langerhans, the cells in the pancreas that secrete the hormone insulin. Because of this, the standard method of combating diabetes is to take a daily dosage of insulin. This does allow the diabetic to live a reasonably normal life, but it does not take into account the cause of the lack of secretion of insulin. Modern research is showing that the prime cause of diabetes is chronic mental stress which, among other things, interferes with the normal secretion of diabetogenic hormone from the pituitary. This explains why the pancreas of a diabetic is often found to be in good condition and no different from the pancreas of a healthy person. Yoga practices, including sirshasana, act directly to harmonize the functioning of the pituitary and to bring its relationship with the brain into balance. This helps to cure diabetes by encouraging the correct secretion of diabetogenic hormone from the pituitary gland.
There are many other hormones secreted by the pituitary gland, too many to discuss in this brief resume. The main purpose of this description is to indicate how vital the pituitary gland is in maintaining perfect health and functioning of the body. If it malfunctions then the whole body will suffer. Even if it works inefficiently, then there will be a tendency for the body to become unhealthy and for the individual to lose vitality. Sirshasana acts directly on the pituitary gland by improving its blood supply, and also the blood supply to its controller, the brain. It is for this reason that sirshasana can harmonize the entire endocrinal system and the multitude of functions that it carries out.