Our body undergoes changes as long as we live. These changes are regulated by special glands in our body known as the endocrine glands. The main function of these glands is to produce chemical secretions called hormones.
Hormones play an important role in control, coordination and regulation of the functioning of tissues, organs and systems in the body. Well harmonized mechanisms regulate the release of very precise quantities of hormones to achieve optimal functioning of the human body.
The endocrine system is responsible for the chemical coordination in our body.
The term hormone has been derived from the Greek word hormaein that means to set in motion or to spur on. A hormone is a chemical secreted by an endocrine gland and carried by blood to a target organ situated elsewhere in the body to stimulate a specific activity.
1. Pituitary Gland
This is a small gland located at the base of the brain. This gland plays an important role in the growth of a child from puberty to the full reproductive maturity. The pituitary gland secretes Gonad Stimulating Hormone, which regulates the activity of gonads (ovary in females and testis in the males).
There is an increase in the activity of this gland at the time of puberty which stimulates the ovary and testes to produce the sex hormones progesterone and oestrogen in females, and testosterone in males. These hormones initiate the development of secondary sexual characters.
The disorders caused by the increased or decreased activity of the pituitary gland include:
Cushing’s Disease: It is caused by the hyperactivity of pituitary gland. In the males, this disease may lead to excessive growth of hair. In some cases, it may even cause atrophy of testes leading to impotency. In the females, this disease causes sterility and masculinization, for example, growth of beard and moustaches.
Deficiency (hypoactivity) of growth hormone (GH) or Somatotropic Hormone (STH) secreted by pituitary gland causes dwarfism (retarded growth of the long bones) which adversely affects the height of a person. On the other hand, its excessive secretion or hyperactivity causes gigantism (excessive growth of long bones) making a person very tall.
2. Thyroid Gland
It is responsible for the speed of metabolism in our body. The thyroid gland is essential for life, growth and development. When the thyroid gland becomes overactive and produces more thyroid hormone than is necessary for optimal functioning, the condition is called Hyperthyroidism. When the thyroid gland becomes underactive and produces less thyroid hormone than is necessary, the condition is called Hypothyroidism.
Cretinism is a condition of severely stunted physical and mental growth due to untreated congenital deficiency of thyroid hormone (hypothyroidism) or from prolonged nutritional deficiency of iodine.
Goitre is a disease of the thyroid gland characterized by an enlargement of the gland, visible externally as a swelling on the front of the neck. Simple goitre is caused by a deficiency of iodine in the diet.
This gland secretes two hormones insulin and glucagon which help in the metabolism of glucose in our body. Hyposecretion of insulin causes diabetes mellitus in which glucose is present in excess in the blood.