WHAT ARE HARMONES?

HORMONES -

Hormones have been called the 'chemical messengers' of the body. They are substances that regulate certain bodily functions such as, growth, development, reproduction, and metabolism. There are eight well-defined endocrine (or ductless) glands in the body. The main endocrine glands are the pituitary, thyroid, parathyroids, pancreas, adrenals, testes and ovaries. In all, they secrete at least 25 hormones into the bloodstream. The absence or excess of hormones causes certain bodily malfunctions such as diabetes, goiter, dwarfism, and gigantism. What are these different endocrine glands and what are the hormones they produce?

An endocrine gland is groups of cells., which take away certain raw materials from the blood and convert them into hormones. The hormones are then released directly into the bloodstream. The pituitary gland is situated near the base of the brain. This gland produces a number of hormones, which control most of the functioning of other glands. One of these hormones controls the growth of the body. If it is overactive, it causes an abnormal growth or gigantism. Similarly, if it is underactive it leads to dwarfism.

The thyroid gland secretes a hormone called 'thyroxin', which is rich in iodine. An abnormality in its secretion can cause serious disorders in the body. If the secretion is insufficient in children then they do not grow in a normal way, either physically or mentally. It controls the oxidation of food in the body. If too little thyroxin is produced, people become very fat. This is because their food is changed into fat instead of being oxidized to produce energy. If the diet lacks iodine, the thyroid gland can get enlarged. This is called 'goitre'. Consuming iodized salt may help to prevent goitre. Our body has four parathyroid glands. Each is about the size of a rice grain. Their hormones enable the teeth and bones to make use of calcium. It is also necessary for proper functioning of the nervous system.

The thymus gland is located in the chest region. To begin with, it is large but becomes progressively smaller as the child grows up. The thymus produces thymosin. Although its function is not clearly understood the hormone apparently protects babies from disease. The adrenal glands are located just above the kidneys. These glands produce a hormone called 'adrenaline' in times of a anger, fear or tension. This increases heartbeat and the amount of energy available to the muscles. The pancreas produces two hormones - pancreatic juice and insulin. Pancreatic juice is used in the digestion of food while insulin controls the amount of sugar in the blood. Insufficiency of insulin results in a disease called 'Diabetes Mellitus'. Its excess, however, can cause hypoglycemia, which is characterized by low blood sugar.

Testes and ovaries are male and female sex glands, respectively. Testes produce testosterone, a male sex hormone. The ovaries produce three hormones-estrogen, progesterone (which controls menstrual cycle) and relaxing. Progesterone plays an important role during pregnancy. Relaxin helps widen the birth canal (vagina) just before the birth of a baby. Hormones control the amounts of various chemical constituents in the body; they regulate the rate of chemical reaction inside the body cells during normal and stressful activities and they control the chemical process involved in growth. One of their most important functions is to maintain functions is to maintain the body's internal environment in a steady state. Specific hormones control the balance of water, important minerals such as, sodium, potassium, calcium, and glucose, which is the main source of energy.

Scientists have now developed synthetic methods for producing hormones. These are used to treat hormonal deficiencies. Synthetic sex hormones are used in birth control pills. Cortisone hormone is often used to treat arthritis and allergies.