Classification Of Glands: Endocrine Glands, Exocrine Glands And Their Hormones

The articles is about glands in human body and their functions. Glands in human body is classified into Endocrine glands, exocrine glands and mixed glands.

Introduction (Types of Glands)

In our body, different types of glands are found which secret different types of juices required by our body. Some of the juices are transported through a duct, where they have to work and some of the secretions are mixed in blood directly. The blood transports them at the related part. 

Glands like, pituitary, thyroid and adrenal secrets their secretion directly into blood, the secretion is called hormones. The glands are called endocrine glands or ductless glands. Secretion of some glands like liver, salivary glands, etc. is transported through the ducts. They are called exocrine glands or ducted glands. While pancreas and gonads are intermediate of them and their secretion is transported by separate duct and through blood both, they are called mixed glands or heterocrine glands. 

How are exocrine glands different from endocrine glands?

Exocrine Glands	Endocrine Glands
They are ducted glands.	They are ductless glands.
They secret juice like mucus, saliva, tear, etc.	They secret hormones.
Their secretions are related life process like respiration, digestion, etc.	Their secretions are responsible for control and co-ordination of growth.
Consumption of their secretion is more in amount.	Consumptionof their secretion is less in amount.
Their secretion is carried by the duct.	Their secretion is carried through the blood.
Examples: Salivary gland, Tear glands, etc.	Examples: Pituitary gland, Thyroid gland, adrenal gland, pancreas etc.

What is a Hormone?

Hormones are chemical substances secreted by heterocrine and endocrine glands. They do not provide energy to the body but have effects on growth and metabolic activities of the target cells. The hormones are popularly called chemical messengers of the body because they are those chemicals who serve as mean of communication among various parts of our body in a co-ordinated way. Hormones are necessary for body in minute doses. If hormones are produced less or in excessive quantity, they cause certain diseases

Types of  endocrine glands and their hornones.

Pituitary gland: 

Pituitary Glands

Pituitary gland is a small endocrine gland of pea size, which is located in skull. Pituitary gland is called master of gland. Why? It is because it controls all the activities of other ductless glands. It secrets growth hormone and stimulating hormone. The hypo-secretion of growth hormone causes dwarfism and hypersecretion causes gigantism.

Thyroid gland 

Thyroid Gland

Thyroid gland is located near the neck, one on each side of the upper part of trachea. The hormone secreted by the thyroid gland is called thyroxine, which contains iodine. The over secretion of this hormone increases the rate of metabolism increase in pulse rate, mental irritability, excessive sweeting and hunger. The less secretion of hormone causes retardation of mental growth, dry skin, slow pulse rate, and sweeting is less.

Parathyroid gland

Parathyroid glands are located on the thyroid gland thus they are named parathyroid gland. There are four parathyroid glands. The hormone secreted by parathyroid glands is called parathormone. The hyposecretion of parathormone causes tetany while excess secretion leads to kidney stone and tumor.

Adrenal gland

Adrenal Gland

Adrenal gland is located on the top of each kidney. These are two in number. They secret adrenalin, aldosterone and hydrosterone hormone. Adrenalin hormone helps to maintain blood pressure of the body. Aldosterone hormone balance salt in the body while hydrosterone hormone balances the water in the body.

Pancreas

Pancreas

Pancreas is called mixed (heterocrine) gland. Why? Pancreas is called mixed gland because it secrets both hormone and enzymes. It is suitated at th loop of the duodenum. It secrets hormones called insulin and glucagon. Insulin decreases the glucose level of the blood. Glucagon increase the glucose level in the blood.

Gonads

 Testes of male and ovaries of female are combinedly called as gonads. It is also a mixed gland. Testes helps to produce sperms and secrets of testosterone hormone. Ovaries produce mature ova and oestrogen hormone.

Table: Glands, hormone and functions

Some main glands with their respective hormones and functions are given below.