A receptor is a protein molecule that receives chemical signal from outside and interprets them. On receiving these signals the receptors bring about cellular responses. There are receptors in nose, tongue, ear, eye etc.

If receptors do not work properly then the information sent by the chemical signals will not be interpreted and perceived. Suppose the receptors found on our tongue, gustatory receptors do not work, an organism will not be able to perceive the taste of things one puts on tongue or eats. If the receptor in eye, say rod, does not work properly then an organism will not be able to perceive vision at night because rods function in less intense lights; so if rods will not function the person will not be able to perceive vision at night. Similarly, If in a situation the receptors in nose, i.e. the olfactory receptors fail to function properly, then the signals sent to brain regarding any smell will not be perceived and an organism will not be able to smell.