The endocrine system

THE ENDOCRINE SYSTEM

The hormones produced by endocrine glands act as messengers between the nervous system and the organs of our body.

The endocrine glands present in the human body are:

• pineal gland
• hypothalamus gland
• pituitary gland
• Thyroid gland
• parathyroid glands
• Thymus; pancreas
• Adrenal glands
• Testes (only in males)
• Ovaries (only in females)

Pineal gland

This gland is located in the brain and releases the melatonin hormone which regulates the wake-up and sleep clock and helps in immunity etc.

Hypothalamus

This gland is a part of the brain that consists of neurosecretory cells and connect both nervous and endocrine systems. The hypothalamus secretes various releasing hormones like gonadotropin-releasing hormones, growth hormone releasing hormones that act on pituitary glands to stimulate other glands.

Pituitary gland

The main centres in the body for the coordination of the two systems of control (nervous system and the endocrine system) are the hypothalamus and pituitary gland.Pituitary gland is present just below the brain and is the master gland. It is pea-sized. They control and regulate other glands in the body.The pituitary gland secretes a number of hormones. One of the hormones secreted by pituitary gland is growth hormone (or human growth hormone). The growth hormone controls the growth of the human body. Other hormones released by this gland are thyroid stimulating hormone, LH, FSH etc

Thyroid gland

Thyroid gland is attached to the wind pipe in our body in front of the neck. It releases the hormones triiodothyronine (T3) and thyroxine (T4). They regulate the body metabolism. Thyroxine hormone controls  the rate of metabolism of carbohydrates, fast and proteins in the body. Iodine is necessary for the making of thyroxine hormone by thyroid gland, therefore. A deficiency of iodine in the diet can cause a deficiency of thyroxine hormone in the body. The deficiency of iodine in the diet of a person produces less thyroxine hormone and cause a disease known as goitre.

Parathyroid gland
This is a butterfly-shaped paired gland and releases parathormone which regulates calcium and phosphorus level in bones.

Adrenal glands

The adrenaline hormone prepares our body to function at maximum efficiency during emergency situations like danger, anger, excitement, etc. Adrenal glands have two regions known as adrenal cortex and adrenal medulla.

• Cortex region secretes the hormones cortisol, aldosterone, and androgens.
• Medulla region secretes the hormones adrenaline and nor-adrenaline.  Adrenaline is the “hormone of fight or flight” which prepares our body to fight an enemy.

Pancreas

The pancreas is just below the stomach in the body. It is endocrine as well as an exocrine gland. Pancreas secretes hormones called glucagon and insulin. which balances  the blood sugar level. Deficiency of insulin hormone in the body causes a disease known as diabetes. The insulin hormone controls the metabolism of sugar.

If due to some reason, pancreas does not produce and secrete sufficient amount of insulin into blood, then the sugar level in the blood rises. The high sugar level in the blood can cause many harmful effects to the body of a person. Other hormones secreted are somatostatin and pancreatic polypeptide.

Testes

Testes make male sex hormones called testosterone. Testosterone hormone controls the development of male sex organs and male features such as deeper voice, moustache, beard, and more body hair than females.

Ovaries

Ovaries are the glands which are present only in females (women). Ovaries make two female sex hormones called oestrogen and progesterone. Oestrogen hormone controls the development of female sex organs, and female features such as feminine voice, soft skin and mammary glands (breasts).