Our senses provide us with information about our environment. These senses respond to a variety of stimuli. The sense of touch is stimulated by the pressure of physical contact with an object. Hearing responds to rapid fluctuations in air pressure.
Sight is produced by electromagnetic radiation falling on the retinas of our eyes.
Because they depend on chemical interactions, these two senses are called chemoreception. Taste is called contact chemoreception, because to experience the flavor of something, we must come into contact with it. Smell is remote chemoreception, for we can sense the odor of an object at a distance. It is simple because relatively few cells are involved in detecting odors. In humans, the olfactory sensors are located at the top of the nasal passages, just below and between the eyes.