The body's hormones, and the glands that produce them, make up the endocrine system. There are eight major glands, and their job is to regulate the body's metabolism, reproduction, growth and sleep.
Like the nervous system, the endocrine system is an information signal system. But rather than using neurons, it uses chemical messengers called hormones, each of which has its own unique function.
Here are 11 interesting facts that may surprise you about the endocrine system, its glands and its hormones.