Final answer:
The endocrine system sends chemical signals through hormones, which travel in the bloodstream and regulate various body functions. These signals are widespread and slower than the neurotransmitter signals of the nervous system.
Step-by-step explanation:
The system that sends signals through chemical messages, specifically hormones, is known as the endocrine system. Hormones are biological messengers produced by endocrine glands, and unlike the neurotransmitters of the nervous system, they are secreted directly into the bloodstream.
This allows hormones to travel throughout the body and bind to receptors on target cells that contain receptors for them, leading to widespread, though generally slower, effects. The hormonal messages regulate essential functions such as development, growth, energy metabolism, and reproduction. The nervous system and the endocrine system work together to maintain homeostasis and regulate the body's physiology.