Cholinergic receptors are proteins found on the surface of cells that respond to the neurotransmitter acetylcholine. They play a crucial role in transmitting signals in both the central and peripheral nervous systems, influencing various bodily functions such as muscle movement and heart rate. There are two main types of cholinergic receptors: nicotinic and muscarinic. Nicotinic receptors are primarily found at the neuromuscular junction and in the autonomic ganglia, while muscarinic receptors are located in various organs and tissues, including the heart and smooth muscles. Both types are essential for proper communication between nerve cells and their target tissues.