The Sense Organs - What is a sense?
A sense is a nerve pathway, one end of which (the receptor end) responds in a certain way to a certain condition affecting our bodies, and whose other end reaches to a part of our brain that informs our conscious mind of what has happened or is happening. A sense is thus distinguished from the body's countless other nerve pathways by the fact that our brain consciously registers its impulses, although the impulses themselves are no different from those of the autonomic nervous system.
While remaining aware of the limitations of the traditional list of five sense organs, let us now analyze what they can do and how they operate:
- • The eye (vision): Nerve impulses to the brain are stimulated by light waves, from which the brain forms visual images.
- • The ears (hearing): Nerve impulses to the brain are stimulated by sound waves, out of which the brain forms meaningful noise, such as speech. Deep within the ear, also, are structures that give us balance.
- • The nose (olfaction): Nerve impulses to the brain are stimulated by airborne chemical substances, moistened within the nasal cavity, from which the brain elicits distinctive smells.
- • The tongue (taste): Nerve impulses to the brain are stimulated (in presence of water) by chemical substances in food, from which the brain forms sensations of sweet, salty, sour, bitter, or combinations of these tastes.
- • Skin (touch): Nerve impulses to the brain are stimulated by the presence of outside physical forces and changes in the physical environment, including varying temperatures, which the brain registers as feelings of contact, pressure, cold, heat, and pain. (Some medical texts add traction, as when the skin is pulled or pinched, as well as the sensation of tickle.)