For the body to function properly, everything needs to be well managed. One of the ways this happens is through hormones, which are chemicals produced by the endocrine system that control specific organs or tissues.

The body systems covered so far in Body Talk have been quite self-contained: for example the cardiovascular system involves the heart pushing oxygen-rich blood around the body by means of blood vessels before it returns via the lungs to be reoxygenated so the cycle can continue.

The endocrine system is a little different because it is comprised only of glands and hormones. A gland is an organ that produces and secretes a chemical substance. Endocrine glands manufacture hormones that are released into the bloodstream to travel to the place in the body where they exert their effect. For example, during pregnancy the pituitary gland releases oxytocin, which travels to the uterus to make it contract. Exocrine glands are slightly different in that they synthesise non-hormone chemicals that are secreted via ducts. For example, the lacrimal glands produce tears that travel via tear ducts to the cornea of the eye to keep it lubricated.