Written by the Fiveable Content Team • Last updated September 2025
Verified for the 2026 exam
Verified for the 2026 exam•Written by the Fiveable Content Team • Last updated September 2025
Definition
In biology, signals refer to the various types of communication between cells. These can be chemical or physical cues that trigger a response in another cell.
These are chemical messengers produced in one part of the body that stimulate or inhibit specific processes in another part.
Neurotransmitters: These are chemicals released by nerve cells to send signals to other nerve cells, muscles, or glands.
Pheromones: These are chemical substances produced and released into the environment by an animal, especially a mammal or an insect, affecting the behavior or physiology of others of its species.