Hormones

There are two ways that signals can travel from one place to another. One way is by nerves, the other is using chemical messengers called hormones.

These are produced by glands in the body and travel through the bloodstream to their target organs.

An important hormone in men is testosterone. This is produced in the testes and effects several parts of the body. Generally the the more testosterone in your bloodstream the more manly you are.

There are important female hormones also. The ovaries and the pituitary gland produce hormones that control a woman's menstrual cycle, i.e. when she releases an egg and what happens to it afterwards.

Here is a summary of the cycle

Quite a few things need to happen at the right time for a woman to reproduce successfully. The egg needs to start developing at the right time When the egg is ready to be released (ovulation) there needs to be a fresh lining of the uterus which will develop into the placenta Ovulation must occur at the right time If the egg isn't fertilised then the lining should be passed out These events are coordinated by hormones

REMEMBER

Many processes within the body are coordinated by chemical substances called hormones. Hormones are secreted by glands and are transported to their target organs by the bloodstream.

Hormones regulate the functions of many organs and cells. For example, the monthly release of an egg from a woman's ovaries and the changes in the thickness of the lining of her womb are controlled by hormones secreted by the pituitary gland and by the ovaries