Question

What are animal hormones? List four characteristics of hormones.

Answer 1

Hormones usually cause long term effects like change in behaviour, growth etc. These are secreted by endocrine glands and act on the target organ only.

Complete step by step answer:
Animal hormones are chemicals secreted by various endocrine glands directly into the blood and transported to the respective organs, where they act by regulating various metabolic processes. The organ is affected by the hormone that means the organ on which the hormone acts is called the target organ. The target cells on the organ have specific receptors to recognize the respective hormones on their surface.
There are two types of glands present in our body:
- Endocrine Glands: These glands do not have ducts so are called ductless glands and transport their secretions directly to the site of action through the blood, e.g. adrenal glands, pituitary glands, etc. These glands secrete hormones.
- Exocrine Glands: These glands have ducts to pass their secretions, e.g., sweat, liver, etc.
Following are the four most important characteristics of hormones:

1. Hormones are chemical messengers secreted by the endocrine glands in small amounts.
2. The hormones are chemical signals secreted directly into the blood and it is transported throughout the body.
3. They are chemical messengers that regulate the behaviour of the target cells but unlike enzymes, they do not catalyze any reaction.
4. The specific hormones act only on the target organs. They are not stored but secreted whenever needed by the target organ.

Note:
- Hormones regulate the behaviour of target cells.
- The hormones and the gland producing them together form a system called the endocrine system. It is associated with the regulation of metabolism, reproduction, growth and sleep in our body.
- In our body, not all hormones come from the endocrine system.