Final answer:
The endocrine system comprises glands that release hormones into the bloodstream, which then travel throughout the body to affect target cells.
Step-by-step explanation:
The endocrine system is comprised of a number of glands known as endocrine glands that release chemical messengers. These messengers are specifically known as hormones and are released into the bloodstream.
Unlike neurotransmitters which communicate signals in close proximity to their target cells mainly in the nervous system, hormones are secreted into the bloodstream and can affect any cells in the body that have receptors for them. The influence of hormones is body-wide and tends to be longer-lasting compared to the localized and faster-acting neurotransmitters.