The Symphony of the Endocrine System: The Effects of Yoga Postures on the Glands
Source: Teaching Asanas, Ananda Marga teacher's manual

Asanas affect every aspect of the human physique; they balance the glandular secretions, relax and tone up the muscles and the nervous system, stimulate circulation, stretch stiff ligaments and tendons, limber joints, massage the internal organs and calm and concentrate the mind. Gradually as the body becomes more accustomed to these limbering relaxing exercises, work becomes an extension of asanas, done at moderate speed with smooth flowing motions, deep breathing to afford the body plenty of oxygen, and a calm and controlled mind alert and responsible to the needs of any situation.

The Glands
The complex symphony of the body is conducted by a system of glands known as the endocrine glands. These glands are often called ductless because they pass their secretions directly into the blood or lymph, instead of using secretory ducts. The chemical substances secreted by these glands are called hormones - chemical messages which act at a distance. Hormones have a profound effect on all the body's functions, including growth, digestion, energy levels, heat, sexuality, water and fluid retention.

Pineal Gland
The pineal body is located directly in the middle of the brain. It has the largest blood supply for its weight of any organ in the body. Obviously, some great activity is going on in this tiny organ, although medical researchers are not sure exactly what. They do know that the pineal gland secrets melatonin which may regulate sexual development and serotonin which seems to be essential for rational thought. The pineal gland also has optic qualities including sensitivity to light in higher animals and humans. It actually has a lens and light-sensitive retina in some lizards. This gland seems to have some importance in regulating the subtle day-to-day rhythms of the body, including sleep. It is unique in that it appears to secrete many substances which have a direct effect on the function of the brain. According to yoga science, the pineal gland is the master gland of the body, controlling all the other glands. Secretions from this gland stimulate all the other lower glands.

Pituitary Gland
The pituitary has been called by medical science the "master gland." In reality it functions as a relay station for impulses arising in the hypothalamus, an organ of the brain which coordinates the nervous system with the glandular system and controls the body's reaction to emotional states. The pituitary gland relays the messages from the hypothalamus to all the endocrine glands of the body. Thus, it may be said that the pituitary hormones excite the movement of the bowels, keep the blood vessels toned up and stimulate the kidneys to do their work. These hormones also control growth and the development and help to regulate the body's temperature. Improper secretion of the pituitary gland results in the abnormal growth of extremely obese people, giants and midgets.

Thyroid and Parathyroid Glands
The thyroid gland in. the neck controls the metabolic rate of the body, the speed at which the chemical processes of the body occur. Like a thermostat, it regulates the level of body heat and energy produced. Among other things, it regulates growth, repair and waste processes. Any imbalance in the thyroid gland has serious consequences. Even a slight over secretion will result in nervous irritability. A slight under secretion will result in a feeling of fatigue and lethargy. The secretions from the parathyroid regulate calcium and phosphorus metabolism.

Thymus Gland
The thymus is a gland located behind the breastbone. It is very large during childhood but at puberty reduces to one-quarter of its original size. It is generally agreed that the thymus exerts a primary role in regulating the immune defenses of the body against disease, but the details of this mechanism and other functions of the thymus are unknown.

Adrenal Glands
The adrenal glands, located just on top of the kidneys, help govern sudden bursts of energy and heat, while stimulating the twin response of staying to fight or running away (the fight or flight response). In a crises, when everything depends on muscular exertion, the brain sends a nervous message to these glands, which promptly pour their secretions into the bloodstream. The secretion of adrenaline speeds up the heart and dilates the blood vessels to the muscles and stimulates the sweat glands so the body may be cooled. It slows the movements of the digestive organs and contracts their blood vessels. It makes the liver shed its stored sugar so the muscles may have a copious supply of fuel. It stands the hair on end, dilates the pupils and widens the eyes, so the individual may be terrifying to look at. It is a chemical S.O.S. A person whose adrenal glands are not able to secrete sufficient adrenaline will not be able to respond properly in a crisis. On the other hand, one whose glands over secrete or secrete inappropriate will speed.

Pancreas
The pancreas lies just below the stomach and secretes digestive enzymes into the small intestine. It secretes insulin, a hormone which lowers the amount of energy-giving glucose in the blood. If the pancreas is unable to secrete sufficient amounts of insulin, blood sugar builds up and diabetes mellitus can result. Too much insulin on the other hand results in hypoglycemia, a condition of trembling and weakness.

Gonads
The gonads (ovaries and testes) primarily govern the sexual function. In the female the ovaries are located in the abdominal area and in the male the testes are located in the scrotum. These glands not only produce sperm and egg cells, but also secrete androgen (male sex hormones) and estrogen (female sex hormones). These hormones regulate physical development of the body and the sexual behavior patterns of the individual. For example, androgens increase the muscular mass of the body and seem to induce aggressive behavior. Estrogens increase fatty padding and may promote passive behavior. Everyone's body produces androgens and estrogens. It is the proper proportion of these hormones which balance the personality.

Effect of Asanas
The entire human organism is controlled by the hormones. Every system, every organ, every tissue, every cell is guided in its functioning by hormones. The proper growth and functioning of the various parts of the body is possible only when there is a balanced secretion of all these hormones. Any imbalance results in disease.

Asanas balance the hormonal secretions from the various glands. The twisting and bending positions of the asanas, held for specific periods of time, place continued and specific pressure on the various glands of the body, thus stimulating them in various ways and regulating their secretions.

In the Shoulder Stand, for example, the contraction of the neck muscles combined with the pressure of the chin on the chest squeezes blood out of the thyroid and parathyroid glands. In the Fish Pose which immediately follows the Shoulder Sstand, the glands are stretched and flooded with blood. The combination of these two poses effectively massages and stimulates these two glands, thus greatly improving their functions.

Different asanas are prescribed to strengthen or regulate the secretion of different glands. For example, the bow pose and wheel pose affect the adrenal glands. In this way many common ailments can be alleviated and the body's harmony restored.