Senses can be defined to be the physiological perception methods. Nervous system has a particular organ or sensory system dedicated to each and every sense. There are five main senses in a human being that includes hearing, smell, touch, taste and sight. Other additional senses include nociception or pain, balance or equilibrioception, joint motion and acceleration (kinaesthesia), temperature difference (thermoception) among others. Each and every sense has specialized cells that have receptors for specific stimuli, the cells are then linked to the nervous system up to the brain. The most developed sense in the human beings is sight followed by the hearing sense.Sight or the vision is the ability of the eye and the brain to detect the electromagnetic waves that are within the visible range. The visible range is usually referred to as light and it is the one which helps the eyes to interpret the image. Some neuro-anatomists regard the vision as two senses taking into consideration that there are different receptors responsible for colour perception or the frequency of light photons as well as brightness or the intensity and amplitude of light. It is also argued that perception of depth also constitute a sense although it is post sensory brain function of interpreting the inputs of sensory as well as deriving new information. Blindness is the disability to see. The main organ associate with this sense is the eye. The main organ associate with vision sense is the eye (Erich, 1997).Hearing or audition is another sense that is associated with sound perception. Because the sound is vibration that moves or propagates through the medium like air, then the sense of hearing can be referred to as the vibrations detection. It is a mechanical sense because the vibrations are mechanically conducted from the ear drums via tiny bones series to fibers that are hair like usually locate in the inner ear. The fiber motion ranges from 20 to20000 hertz although it varies from one individual to another. The frequency of hearing usually declines with age. The inability of a person to hear is called deafness. The main organ associated with hearing sense is called an ear. The outer part of the ear protrudes from the head and it is usually shaped like a cup so as to direct the sound to the tympanic membrane. The tympanic membrane usually transmits the vibrations to the inner ear through some small bones called incus, stapes and malleus (John, & Mitchinson, 2007).
Another sense found in the body is taste or gestation. It is one of the two main chemical senses. There are four types of tastes that are detected by the receptors or the tongue. It is argued that there are more than five different senses as each receptor transmits information to different brain regions. Ageusia is the inability of the body to detect the taste. The known receptors that are common usually detect salt, sour, sweet and bitter. There also exists a fifth receptor for sensation that is called umami. This is the sensation of the amino acids. The organ associate with tasting is called the tongue; it has taste receptors that are referred to as taste buds. These receptors are located near the pharynx and at the roof of the mouth. Taste buds at the tip of the tongue are sensitive to sweet tastes while those at the rear of the tongue are usually sensitive to tastes that are bitter. The top and side taste buds on the tongue are usually sensitive to sour and salty tastes. The sensations are sent to the brain through the nerves located at the base of each taste bud, these nerves sends the sensation to the brain.
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Smell or olfaction is a sense which is usually a chemical sense. There are a number of olfactory receptors where by each binds in a particular feature. The molecule of odor has several varieties of features, which enables it to excite specific receptors less or even more strongly. Anosmia is the inability to smell. The main organ associate with smelling is the nose. The nose cavity has mucous membranes which is lined within it and has smell receptors that are connected to the olfactory nerve. Smell is usually the vapor of a substance; the vapor interacts with the smell receptors which end up transmitting the sensation to the brain.The last main sense within the body is the touch. This is also referred to as tactition or mechanoreception. This is a perception which results from neural receptors activation especially in the skin that includes hair follicles. It is also found in the throat, mucosa and the tongue. There are several pressure receptors which respond or change as the pressure varies. The pressure variation varies from brushing, sustained or firm pressure. The itching sense of touch that is cause by the insect bites or even allergies usually involves special itch specific neurons in spinal cord or skin. Tactile anesthesia is the term that is used to refer to the loss of feeling anything touched. The touch sense is usually distributed throughout the body; the endings of the nerve in the skin transmit sensations to the brain. The number of nerve endings varies from one part of the body to another hence the sensitivity varies from one person to another. There are usually four types of touch sensations; they include contact, pain, heat and cold. The sensitivity is usually magnified by the hair skins hence acting as a warning system of the body (Antonio, 2004).
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