A fish of all flavours
(PHYSorg.com Chemistry)

Receptors are how the body senses its environment. Upon the binding of a ligand, a receptor will initiate a chain of events that elicits a response. Our olfactory system depends on approximately 400 receptors to give us our sense of smell. Taste, however, operates with a much smaller number: The combination of only three members of the taste receptor type 1 (T1r) family can detect a wide range of sweet and savory flavours in humans.