Hormones in animals

HORMONES IN ANIMALS

Animals including humans have a complex system of living including the nervous system and endocrine system for control and coordination. The endocrine system controls numerous involuntary physiological activities is responsible for the chemical coordination. It consists of endocrine glands which release hormones and are also called ductless glands. Hormones are the chemical substance which coordinates the activities of living organism and also their growth. Hormones are a kind of chemical messengers. Hormones are necessary for various activities in the body including growth and development and support to the nervous system.

The various characteristics of hormones are given below:

• The hormones are secreted in small amounts by the endocrine glands.
• The hormones have their effect at the sites different from the sites where they are made. So, they are also called chemical messengers.
• The hormones are poured directly into the blood and carried throughout the body by blood circulatory system.
• The hormones coordinate the activities of the body and also its growth.
• The hormones act on specific tissues or organs (called target organs).

There are two types of glands in the body:

• exocrine glands
• endocrine glands

Exocrine gland:

A gland which secretes its product into a duct (or tube) is called an exocrine gland.

For e.g. the salivary gland

Endocrine gland:
A gland which does not have a duct and secretes its product directly into the blood stream is called an endocrine gland. Endocrine glands are ductless glands. Hormones are a kind of chemical messengers.