M1, M2, M3, M4, M5 receptors

M1, M2, M3, M4, and M5 are types of receptors in the brain and body that respond to the neurotransmitter acetylcholine. Think of them as specialized locks on cells, each with unique functions. M1 receptors are mainly in the brain, involved in cognition and memory. M2 receptors are in the heart, helping regulate heart rate. M3 receptors are in glands and smooth muscles, controlling secretions and muscle contractions. M4 and M5 are primarily found in the brain, influencing dopamine and other neurotransmitter pathways, affecting mood, learning, and motor control. Each receptor type plays a distinct role in how nerves communicate and organs function.