The Endocrine System

Endo means internal & crinos means secretion. So Endocrine means internal secretion.

Endocrinology is a branch of medical science which deals with the study of different endocrine glands of the body.

Endocrine gland: Means ductless gland which directly poured their secretion into the blood.

Endocrine system: The system which deals with endocrine glands & their secretions.

Organs of Endocrine System: The Endocrine System consists of the following glands.

1, Pineal gland

2, Hypothalamus

3, Pituitary gland – Anterior part & Posterior part.

4, Thyroid gland

5, Para – thyroid gland

6, Adrenal gland – Adrenal cortex & Adrenal medulla

7, Pancreas

8, Testis

9, Ovary

1, Pineal gland: A pea-sized mass of tissue attached by a stalk to the posterior wall of the third ventricle of the brain, deep between the cerebral hemispheres at the back of the skull. It may play a part in initiating the development of the gonads; in other mammals it secretes the hormone like substance melatonin. In humans, melatonin may be involved in the onset of puberty ( the time at which the onset of sexual maturity occurs).

2, Hypothalamus: The region of the forebrain in the floor of the third ventricle, linked with the thalamus above & the pituitary gland below. It contains several important centers controlling body temperature, thirst, hunger, eating, water balance & sexual function. It is also closely connected with emotional activity & sleep & functions as a center for the integration of hormonal & autonomic nervous activity through its control of pituitary secretions.

Major endocrine gland with their position, secreted hormone & function are follows:

 

Name of gland	position	Hormone	Function
Adrenal cortex	Outer portion of gland on top of kidney	cortisol, Aldosterone	Metabolism of carbohydrates, fat & Protein. Reduce sodium & increase K+ excretion by kidney.
Adrenal Medulla	Inner portion of gland surrounded by adrenal cortex.	Adrenaline, Nor-adrenaline	Increases carbohydrate use of energy.
Pancreas	In abdominal cavity	Insulin, Glucagons	Promotes glucose entry in cell & helps in carbohydrate metabolism. Increase the synthesis of & release of glucose from liver into body fluid.
Parathyroid	On back of thyroid gland	Parathormone	Controls calcium & phosphorus metabolism.
Pituitary, anterior	Front portion of small gland below hypothalamus	Growth hormone, TSH, FSH, Prolactin, Leutinizing hormone, Adrenocrticotropin	Influences growth, sexual development, skin pigmentation, thyroid function, adrenocortical function through effects on other endocrine gland.
Pituitary, Posterior	Back portion of small gland below hypothalamus	Antidiuretic hormone, Oxytocin	Antidiuretic hormone increases absorption of water by kidney tubule. Oxytocin increases urerine contraction.
Testes	In the scrotum	Testosterone	Stimulate the growth & development of male sexual characteristics.
Ovaries	In the pelvic cavity	Estrohen, Progesterone	Stimulate the growth & development of female sexual characteristics.
Thyroid	Two lobes in anterior portion of neck	Thyroxin, tri-iodothyronin, Calcitonin	Increases metabolic rate; indirectly influences growth & nutrition.

 TSH = Thyroid Stimulating Hormone, FSH = Follicle Stimulating Hormone

Hormone: Hormone is a chemical substance that is secreted into the internal body fluid by one cell or group of cell & excretes a physiological control effect on other cells of the body. 

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