Explanation

Hormones are messengers that tell certain cells in different parts of your body what to do. They are produced by glands, and they get their instructions from your brain. Hormones keep your body running smoothly, by balancing everything and working together to keep you healthy and functioning properly.

Each hormone travels through your bloodstream until it finds its target cell. It then uses a key on its surface to open a matching lock on the door of that cell. When the cell has been unlocked, the message gets delivered inside and thecell is told what to do.

Hormones control so many things, including when you feel hungry or full, when and how you sleep, your body temperature, how fast your heart beats, whether you are fat or thin and a whole lot more - even how and when you grow!