Our Senses—Remarkable Gifts
AT THE sight of the ice cream, Luke’s eyes shine. As he reaches out to grasp the cone verbally offered to him, his mouth waters. He raises the delicacy to his mouth, smelling its sweetness as he does. Then, he tastes the delicious flavor with the first lick of the soft, cold ice cream.
In this delightful experience, Luke makes use of his body’s five remarkable senses—sight, hearing, touch, smell, and taste. Yet we have many other senses; how many depends on how one wishes to classify them. For example, the skin has sensitivity not only to touch but also to temperature (warm and cold) as well as to pain. The inner ear, besides being sensitive to sound, regulates our sense of balance by means of fluid that flows within its semicircular canals. In addition, there are receptors in the body that are responsible for our sense of hunger and thirst, as well as other senses.
Thus, by means of an intricate communication system, our body responds to various stimuli to measure physical and chemical characteristics of our environment. Consider a few specifics.
The eye receives a continual flow of visual impressions. Light is focused on the millions of receptor cells of the retina, which responds to the light rays by producing electrical signals. The optic nerve carries the signals to the brain, where they are interpreted as visual images.
The ear has tiny hairs located in its inner part that oscillate in rhythm with the sound waves they pick up. They then feed electrical information that our brain interprets as sound.
Touch is a sense dependent on small receptors located in the skin. Apparently, different receptor cells are responsible for the various sensations of touch, pain, cold, and heat.
Taste is a sense made possible by microscopic nerve endings called taste buds. By means of these buds situated principally on the tongue, and to a lesser extent on other surfaces of the mouth, we can relish our food and drink.
Smell is closely linked to taste. The extraordinary sensitivity of the receptor cells housed in the roof of the nasal cavity enables them to detect just 1 molecule of some odorous substances in 1,000,000,000,000 parts of air! But just how these cells detect odors and give rise to nerve signals in the brain still baffles researchers.
Truly, our senses are remarkable gifts. What happens, though, when they are impaired? How do we cope? What can we do?