Chemical messengers are substances that transmit signals between cells in the body. They play a crucial role in regulating various physiological processes, including growth, metabolism, and mood. Common types of chemical messengers include hormones, neurotransmitters, and cytokines, each serving specific functions in communication within the body. These messengers are released by one cell and travel to target cells, where they bind to specific receptors. This binding triggers a response, allowing the body to maintain homeostasis and respond to changes in the environment. Examples of chemical messengers include insulin, which regulates blood sugar levels, and serotonin, which influences mood and behavior.