Human Senses

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Our senses enable us to make sense of the world around us; they make our environment enjoyable by stimulating our desire to eat giving the body the vital nutrients it needs. They can also alert us to a fire before we see the flames, detect dangerous fumes and smell and taste rotten foods. Out of the five senses, it seems like taste is one of the simplest. There are no cones; rods or lenses, there are no tympanic membranes or miniscule bones. Our sense of smell in responsible for about 80% of what we taste. Without our sense of smell, our sense of taste is limited to only five distinct sensations: sweet, salty, sour, bitter and savory sensation. All other flavors that we experience come from smell. This is why, when our nose is blocked, as by a cold, most foods seem bland or tasteless. Our sense of smell becomes stronger when we are hungry. Smell and taste are closely linked. The taste buds of the tongue identify taste; the nerves in the nose identify smell. Both sensations are communicated to the brain, which integrates the information so that flavors can be recognized and appreciated. Some tastes—such as salty, bitter, sweet, and sour—can be recognized without the sense of smell. However, more complex flavors require both taste and smell sensations to be recognized.

Different stimuli activate different sensory receptors. Chemical stimuli activate the chemoreceptors responsible for gustatory and olfactory perceptions. Because taste and smell are both reactions to the chemical makeup of solutions, the two senses are closely related. Taste is a chemical sense perceived by specialized receptor cells that make up taste buds.

In humans, the chemoreceptor’s that detect taste are called gustatory receptor cells. About 50 receptor cells as well as basal and supporting cells make up one taste bud. Taste buds themselves are contained in goblet-shaped papillae. Some papillae help create friction between the tongue and food. There are four different types of...
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