cure diseases

The Important Endocrine Glands

The Important Endocrine Glands

 Endocrine System, Important endocrine glands, pituitary gland , anterior lobe, posterior lobe, thyroid gland , parathyroid gland , andrenal glands. pancreas, gonads, 

Endocrine system

The activities such as growth, reproduction, maintenance of glucose  concentration in blood,reabsorption of water in kidneys etc.need to be regulated.Endocrine system system perform this  job.This system uses chemicals  to communicated with its efffectors. These chemicals are known as hormones. A hormone is a specific messenger molecules synthesized and secreted by an endocrine gland.These glands are ductless and release their secretions directly into bloodstream.Blood caries the hormones  to target organs or tissues upon which they act.

The Important Endocrine Glands

1.Pituitary Gland:

It is a pea shaped gland attached to the hypothalamus of brain.Many  hormones(trophic hormones)   of pituitary gland influence the secretions of other endocrine glands.However some hormones of this glands  act directly on various tissues of body.There are two lobes of pituitary glands  it mean anterior lobe or posterior lobe . 

a. Anterior  Lobe :

It produces many hormones.One of its important hormones is somatotrophin.It promotes the growth of body. If the production of this hormone is diminished during growing age the rate of growth decreases. This condition is called dwarfish.If this hormone is excessively produce during growing condition is call gigantism. If somatotrophin is excessively produce after growing age internal organs and body extremities along grow large. This condition is known as acromegaly. Such person will have large hands, feet and jawbones.

Thyroid-stimulating hormone:

It stimulate thyroid gland to secret its hormones. They remaing hormone of anterior lobe influence reproductive organs and also control adrenal glands.

b.Posterior Lobe:

They posterior lobe of pituitary gland stores and secretes two hormones i.e Oxytocin and Vasopressin. These hormone are produce hypothalamus. 

Vasopressin:

Increases the rate of reabsorption of water from nephrons. When we have low amount of water in body fluids, pituitary gland secret vasopressin and so more reabsorption of water occurs from nephrons into blood.

In this way, body retains water and less amount urine is produced. On the other hand, when body fluids have more than normal water, there is a decline in the secretion of this hormone. If pituitary gland does not secret this hormone in the required amount, less water is reabsorbed from nephrons and there excessive loss of water through urine. This condition is know as diabetes insipidus.

The hormone Oxytocin stimulate the contraction of uterus walls in the mothers for child birth. Moreover, this hormone is necessary for the ejection of milk from breast.

2. Thyroid gland:

Thyroid gland is the largest endocrine gland in human body. It is prsent in neck region, below larynx, and the produces a hormone thyroxin. Iodine is required for the production of this hormone. If a person lacks iodine in diet,  thyroid gland can not make its hormone. In this condition, thyroid gland en larges.
Thyroid gland  disorder is called goitre.

Thyroxin increases break down of food and release of energy in body. It is also responsible for the growth of body.

Hypothyroidism is cause by the under-production of thyroxin. It is characterized by low energy production in body and slowing down of heart beat. Hyperthyroidism is cause by over-production of thyroxin. Its symptoms are increase in energy production, increase heart beat, frequent sweating and shivering of hands.

The thyriod gland produces an other hormone called calcitonin. It deceases the level of calcium ions in blood and promotes the absorption of calcium from blood into the bones.

3.Parathyroid Glands:

Thea are four glands situated in the posterior side of thyroid gland.They produce a hormone known as parathormone. It increases the level of calcium ions in the blood. 

When there is increased production of parathormone more than normal calcium salts are absorbed from the bones and added to blood.Consequently the bones become brittle.If there is dificiency in the production of parathormone, blood calcium level falls.It leads to tetany, which affect the functioning of muscles.

4.Adrenal glands:

Two adrenal glands are situated above kidneys.Each adrenal glands consists of two parts. The outer part is cortex and the inner part is medulla.Adrenal medulla secretes a hormone called epinephrine or adrenaline in response to stress.It prepares our body to overcome emergency situations .Therefore adrenaline is also termed as 'emergency hormone'. The adrenal cortex secrets many hormones called  corticosteriods  which maintain the balance of salts and water in blood.

5.Pancreas:

This organ has two function. The major part of pancreas is a ducted gland.This portion secrets digestive enzymes.through  a duct into the small intestine.Some portion of pancreas serve as ductless gland .This portion contains groups of endocrine cells referred as islets of Langerhans.These islets secrete  two hormones i.e. insulin and glucagon.Glucagon influences the liver to release glucose in blood and so the blood glucose concentration rises. Insulin influences the liver excess to  glucose from blood and so the blood glucose concentration falls.

If a person's pancreas does not make normal quantity of  insulin, the blood glucose concentration rises  and we say that the person has  diabetes mellitus.Persons with diabetes have loss of body weight,weakening of muscles and tiredness.the disease can be controlled by insulin administration. Formerly insulin extracted from animals as used for this purpose.But now human insulin produced from bacteria  through genetic engineering is available.

6.Gonads:

Testis and ovaries are male and female reproductive organs i.e gonads.In addition to producing gametes , gonads also secrets  hormones, called sex hormones.Testes secrete hormone e.g. testosterone,which is responsible for the male secondary sex characters such as growth of hair on face and coarseness of voice etc.

Ovaries secrete estrogen and progesterone,which are responsible for the development of female secondary characters such as the development of breast etc.