What are hormones?

Hormones are chemical substances in the body. They are made by endocrine glands which pass the hormones directly into the bloodstream. They are carried around the body in the blood and, in this way, hormones can cause changes at some distance from the gland where they were made.

Contents

What do hormones do?

A woman with a blank face holds two faces, one happy and one sad
Good day? Bad day? Hormones can make the difference.
Many processes in the body are coordinated by hormones which regulate and balance the working of organs and cells.

Some hormones have long term effects, for example, the hormones that control how we grow and the changes that happen at puberty. Other hormones have shorter term effects.

Too much, or too little, of a hormone can cause illness. Synthetic hormones, developed by pharmaceutical companies, have resulted in a great improvement in the quality of life of patients suffering from many of these illnesses.

Using this e-source

There are a number of interactive features in this e-source:
  • A glossary of terms: any word with a glossary entry is highlighted like this.
  • Quick questions: at the end of a page/section, there is a set of quick questions to test your understanding of the scientific ideas.
  • Roll over diagrams: many of the diagrams have highlights or sequences. You can see these by rolling your cursor over part of the picture or part of the text.