Final answer:
Hormones are chemical messengers that originate from the endocrine system and travel through the bloodstream to affect target cells.
Step-by-step explanation:
The endocrine system is responsible for releasing chemical messenger molecules called hormones into the bloodstream. These hormones act slowly compared to the rapid transmission of electrical messages by the nervous system. Endocrine hormones travel throughout the body and can affect many cells, resulting in body-wide effects.