Neuroscience: The Five Senses
Table of Contents:
Sense 1: Taste
Sense 2: Smell
Sense 3: Sight
Sense 4: Hearing
Sense 5: Touch
Neuroscience is the study of the nervous system and anything that is involved with the nervous system. They are many different areas in the field if neuroscience. Neuroscience deals with the five senses, anything connected to the nervous system, the brain, anything that sends information to and from the brain, etc. Many of these things go from simple ideas and concepts to the complex coding of the brain, and everything in between. One of the areas of study that can go from being simple to complex easily is the study of the five senses, sight, hearing, taste, smell, and touch. These five senses may seem simple to describe and easy to define, but they are some of the most complex functions in the human body. Some might say, "How does this pertain to neuroscience?", and this is a logical question. The answer to that is that each of these five senses involves neurons, and these neurons have to be dealt with. The bodily function that deals with these neurons is the nervous system. In fact that is all the nervous system deals with, it's a sort of second brain for neurons. The first of these senses is taste, or gustation. Taste, as everyone knows, is what happens when some thing is placed on the tongue. A more technical definition is that it is the direct detection of chemical composition, usually through contact with the tongue. The tongue is the muscle that has different nerves on it that relay information to the brain, via the nervous system. This information is put back together and depending on your likes and dislikes, you either spit the food out or keep eating.
The tongue is covered with chemoreceptor cells that detect the chemical composition of foods or drink, or anything put into the mouth. Also in the tongue are taste buds. There are about 10,000 taste buds on the tongue. These taste buds are linked to the brain by nerve fibers, and when food is detected by the taste buds, they relay signals to the brain. In technical terms the sense of taste is picked up by the taste buds and conveyed via three of the twelve cranial nerves. First is the facial nerve that carries the taste signals from the two-thirds of the tongue that is showing, the other third is carried by the glossopharyngeal nerve, and the vagus nerve carries some from the back of the mouth. This information is then processed by the gustatory system, the taste sub-system of the nervous system. With this information, the brain then decides if it likes what it is eating or not. On the tongue are also the four well-known receptors that determine and detect sweet, salt, sour, and bitter. The bitter receptors are on the back of the tongue. While the receptors that detect saltiness are on the very tip of the tongue. Sweetness is detected on most of the front half of the tongue, while the sour receptors are on the back half on the sides. The sense that works similarly to taste is the sense of smell. Smell, or olfaction, is another chemical sense. Unlike taste, there are hundreds of olfactory receptors, each that bind to particular molecular feature. So where taste used taste buds to detect a chemical composition, these receptors will detect a distinct molecular feature of an odor. Just like taste, smell has its own sub-system of the Brandt 5
nervous system, this is called olfactory system. Unlike all the other senses the, the olfactory receptors will die and regenerate on a regular basis. The organ that centralizes the olfaction system is the nose. The nose on vertebrates normally houses the nostrils, which admit and expel air for respiration. In most mammals, the nose also houses the nose hairs, which catch airborne particles and prevent them from getting to...
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5) Encyclopedia Americana (2000). Smell. Encyclopedia Americana(Vol. 25 pp. 50) USA: Grolier
6) Karlson, B.M. (2000). Nose. Encyclopedia Americana(Vol. 20 pp. 482-485) USA: Grolier
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