Gland

One way it does this is through the endocrine system: a group of glands that secrete chemical messengers called hormones directly into the bloodstream. The blood carries a hormone around the body to a target organ, where it produces an effect. Although the hormone circulates widely, only cells able to respond to that particular hormone act on its message.

The endocrine system provides one form of communication. Its endocrine glands produce chemical messengers called hormones.

Hormones are produced and secreted by glands. They enter the bloodstream and are carried in the blood around the body. This allows a gland in one place to control an effector elsewhere in the body.