Endocrine System

Section 1What the endocrine system does

The endocrine system helps coordinate body activities using chemicals called hormones. Hormones are made by endocrine glands and released into the blood. In plain words, hormones are body messages that travel through the bloodstream.

Section 2Hormones and target organs

A hormone does not affect every part of the body. It travels in the blood, but only target organs or target cells respond to it. Here's the trick: the hormone is the message, and the target organ is the part that can read that message.

Section 3Examples of endocrine glands

Important endocrine glands include the pituitary gland, thyroid gland, pancreas, adrenal glands, ovaries, and testes. Each gland releases particular hormones. For example, the pancreas releases insulin, which helps control blood sugar level.

Section 4Nervous versus hormonal control

The nervous system sends electrical impulses quickly through neurones. The endocrine system sends chemical messages more slowly through blood. Watch out: slower does not mean less important; growth, puberty, stress responses, and blood sugar control all rely on hormones.

Section 5Everyday hormone responses

If you nearly trip during a football game, adrenaline can make your heart beat faster and prepare your body for action. After eating rice and peas at lunch, insulin helps move glucose from the blood into cells. These are coordination responses, just not as instant as a reflex.