Glands

Glands- A Gland is a group of cell in organism’s body that produces chemicals.

The substances produced by glands may be Hormones or breast Milk.

Glands can be divided into two types:

1.Exocrine Glands: Exocrine glands are the type of glands which do not pour their secretion in blood. They have their ducts to pour their secretion to Target organs.

Eg- Tear Glands, Sweat Glands, Salivary Glands.

2.Endocrine Glands:

Endocrine System and its function

These glands are also known as ductless glands.

These glands secrete the chemical substances called hormones and directly pour hormones into blood or lymph system.

There are number of endocrine Glands secreting different hormones.

Such glands are responsible for controlling human behaviours.

Six different Endocrine Glands are described below:

1) Pituitary Gland: Pituitary gland is oval shaped structure lying at the base of the brain. The pituitary gland is often referred as the master gland for the hormones it produces control other endocrine secretions.

 It has two lobes called Anterior and Posterior pituitary.

a. Anterior pituitary secrets various hormones including growth hormone.

b.Posterior pituitary

Functions:

vPosterior pituitary releases hormones that regulate the absorption of  water by kidney.

vIn female the production of pituitary gland (Prolactin) plays role in production and release of milk.

2.Adrenal Gland: There are two adrenal glands located at the tip of the kidneys.

 Each adrenal gland has two parts:

A. An inner layer called Adrenal Medulla

B. Outer layer called Adrenal Cortex

Functions:

vThe secretion of Adrenal Cortex controls the body minerals and increases carbohydrate metabolism.

vSecretion of Adrenal Medulla helps to increase the sympathetic activity during emergency and prepares individual to deal with stress.

vThe adrenal cortex also makes sex hormones.

vAdrenal gland also plays role in controlling heart rate and blood pressure.

3.Thyroid gland: The thyroid gland is a brownish-red structure lying on the sides of the throat.

The secretion of thyroid gland called thyroxin is an important regulator of metabolic rate.

Functions:

vThe steady secretion of thyroxin provides for the minimum rate at which body cells take in sources of energy, consume oxygen and eliminate wastes.

vThe secretion of thyroid gland plays vital role in regulating body temperature

vThe hormone is very important for normal growth and development especially in Central nervous system.

vThyroxin also assists other organs in body in their function.

vLow level of thyroxin leads to mental retardation)

v

while high level of it produces  may lead to (over excitability, and  reduced capacity to focus upon a particular task).

4. Parathyroid gland: Parathyroid gland is a set of four small organs lying behind the thyroid gland in neck.

The parathyroid gland secretes a hormone called parathyrin that is responsible to produce calcium and phosphorus metabolism.

Function:

vparathyrin contributes for the maintaining the optimum level of calcium in body.

vDeficiency of too low level of calcium in body produces hyper excitability (may lead to seizures attacks) while too high level of calcium produces low excitability)

vThe calcium is ultimately responsible for the development of bone..

5. Gonads: The gonads is also known as sex glands, are different in men and women.

The gonad in male is called Testes and in female called Ovaries.

These glands are primarily responsible for producing sex hormones that contribute for primary and secondary sexual characteristics in men and women.

 The hormone produced by testes is called Testosterone and that produced by ovary in women are called Estrogen.

6.Pineal Gland: Pineal gland is small endocrine gland that lies within the brain between two cerebral hemispheres.

 It secrets the hormone called Melatonin.

Functions:

vIt regulates sleeping cycle.

vIt acts to keep child’s body from undergoing sexual meturation.This is supported by the fact that children with tumors of the pinal glaneal gland often reach sexual maturity unusually early in life.presumbaly because the pineal’s production of melatonin has been hampered.