Principles of Biochemistry (2+1)

9.1.1 Hormones

Learning Objectives

A hormone is a chemical substance or messenger, secreted in trace amounts by one type of tissue and carried by the blood to a target tissue elsewhere in the body to stimulate a specific biochemical or physiological activity. In higher animals, special ductless endocrine glands synthesize endocrine hormones that they release into the bloodstream in response to external stimuli. They are then carried to their target cells in which they elicit a response.

 

Functions

The hormones have three important functions: they enable the body to maintain homostasis, respond to a wide variety of external stimuli and to regulate various cyclic and development programmes.