Difference between revisions of "Five senses"
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− | '''Sight''' or '''vision''' is the capability of the eye(s) to focus and detect images of visible light on photoreceptors in the retina of each eye that generates electrical nerve impulses for varying colors, hues, and brightness. There are two types of photoreceptors: rods and cones. Rods are very sensitive to light, but do not distinguish colors. Cones distinguish colors, but are less sensitive to dim light. There is some disagreement as to whether this constitutes one, two or three senses. Neuroanatomists generally regard it as two senses, given that different receptors are responsible for the perception of color and brightness. Some argue that stereopsis, the perception of depth using both eyes, also constitutes a sense, but it is generally regarded as a cognitive (that is, post-sensory) function of the visual cortex of the brain where patterns and objects in images are recognized and interpreted based on previously learned information. This is called visual memory. | + | '''[[Sight]]''' or '''[[vision]]''' is the capability of the [[eye]](s) to focus and detect images of [[visible]] [[light]] on {{Wiki|photoreceptors}} in the {{Wiki|retina}} of each [[eye]] that generates electrical {{Wiki|nerve}} {{Wiki|impulses}} for varying colors, hues, and [[brightness]]. There are two types of {{Wiki|photoreceptors}}: rods and cones. Rods are very [[sensitive]] to [[light]], but do not distinguish colors. Cones distinguish colors, but are less [[sensitive]] to dim [[light]]. There is some disagreement as to whether this constitutes one, two or three [[senses]]. Neuroanatomists generally regard it as two [[senses]], given that different {{Wiki|receptors}} are responsible for the [[perception]] of {{Wiki|color}} and [[brightness]]. Some argue that stereopsis, the [[perception]] of depth using both [[eyes]], also constitutes a [[sense]], but it is generally regarded as a [[cognitive]] (that is, post-sensory) function of the [[visual]] cortex of the {{Wiki|brain}} where patterns and [[objects]] in images are [[recognized]] and interpreted based on previously learned [[information]]. This is called [[visual]] [[memory]]. |
− | The inability to see is called blindness. Blindness may result from damage to the eyeball, especially to the retina, damage to the optic nerve that connects each eye to the brain, and/or from stroke (infarcts in the brain). Temporary or permanent blindness can be caused by poisons or medications. | + | The inability to see is called {{Wiki|blindness}}. {{Wiki|Blindness}} may result from damage to the {{Wiki|eyeball}}, especially to the {{Wiki|retina}}, damage to the optic {{Wiki|nerve}} that connects each [[eye]] to the {{Wiki|brain}}, and/or from stroke (infarcts in the {{Wiki|brain}}). Temporary or [[permanent]] {{Wiki|blindness}} can be [[caused]] by [[poisons]] or medications. |
− | People who are blind from degradation or damage to the visual cortex, but still have functional eyes, are actually capable of some level of vision and reaction to visual stimuli but not a conscious perception; this is known as blindsight. People with blindsight are usually not aware that they are reacting to visual sources, and instead just unconsciously adapt their behaviour to the stimulus. | + | [[People]] who are [[blind]] from degradation or damage to the [[visual]] cortex, but still have functional [[eyes]], are actually capable of some level of [[vision]] and {{Wiki|reaction}} to [[visual]] {{Wiki|stimuli}} but not a [[conscious]] [[perception]]; this is known as {{Wiki|blindsight}}. [[People]] with {{Wiki|blindsight}} are usually not {{Wiki|aware}} that they are reacting to [[visual]] sources, and instead just {{Wiki|unconsciously}} adapt their {{Wiki|behaviour}} to the {{Wiki|stimulus}}. |
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− | + | ==== [[Hearing]] ==== | |
− | ''' | + | '''[[Hearing]]''' or audition is the [[sense]] of [[sound]] [[perception]]. [[Hearing]] is all about vibration. {{Wiki|Mechanoreceptors}} turn {{Wiki|motion}} into electrical {{Wiki|nerve}} pulses, which are located in the inner {{Wiki|ear}}. Since [[sound]] is {{Wiki|vibrations}} {{Wiki|propagating}} through a {{Wiki|medium}} such as [[air]], the detection of these {{Wiki|vibrations}}, that is the [[sense]] of the [[hearing]], is a mechanical [[sense]] because these {{Wiki|vibrations}} are mechanically conducted from the eardrum through a series of tiny {{Wiki|bones}} to [[hair]]-like fibers in the inner {{Wiki|ear}}, which detect mechanical {{Wiki|motion}} of the fibers within a range of about 20 to 20,000 hertz, with substantial variation between {{Wiki|individuals}}. [[Hearing]] at high frequencies declines with an increase in age. Inability to hear is called deafness or [[hearing]] {{Wiki|impairment}}. [[Sound]] can also be detected as {{Wiki|vibrations}} conducted through the [[body]] by {{Wiki|tactition}}. Lower frequencies than can be heard are detected this way. |
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+ | ==== {{Wiki|Taste}} ==== | ||
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− | '''Taste''' (or, the more formal term, gustation; adjectival form: "gustatory") is one of the traditional five senses. It refers to the capability to detect the taste of substances such as food, certain minerals, and poisons, etc. The sense of taste is often confused with the "sense" of flavor, which is a combination of taste and smell perception. Flavor depends on odor, texture, and temperature as well as on taste. Humans receive tastes through sensory organs called taste buds, or gustatory calyculi, concentrated on the upper surface of the tongue. There are five basic tastes: sweet, bitter, sour, salty and umami. Other tastes such as calcium and free fatty acids may be other basic tastes but have yet to receive widespread acceptance. | + | '''{{Wiki|Taste}}''' (or, the more formal term, {{Wiki|gustation}}; adjectival [[form]]: "{{Wiki|gustatory}}") is one of the [[traditional]] [[five senses]]. It refers to the capability to detect the {{Wiki|taste}} of {{Wiki|substances}} such as [[food]], certain {{Wiki|minerals}}, and [[poisons]], etc. The [[sense]] of {{Wiki|taste}} is often confused with the "[[sense]]" of {{Wiki|flavor}}, which is a combination of {{Wiki|taste}} and {{Wiki|smell}} [[perception]]. Flavor depends on {{Wiki|odor}}, {{Wiki|texture}}, and temperature as well as on {{Wiki|taste}}. [[Humans]] receive {{Wiki|tastes}} through {{Wiki|sensory organs}} called {{Wiki|taste}} buds, or {{Wiki|gustatory}} calyculi, [[concentrated]] on the upper surface of the {{Wiki|tongue}}. There are five basic {{Wiki|tastes}}: sweet, [[bitter]], [[sour]], [[salty]] and {{Wiki|umami}}. Other {{Wiki|tastes}} such as calcium and free {{Wiki|fatty acids}} may be other basic {{Wiki|tastes}} but have yet to receive widespread [[acceptance]]. |
− | Smell | + | |
+ | ==== {{Wiki|Smell}} ==== | ||
+ | |||
+ | '''{{Wiki|Smell}}''' or {{Wiki|olfaction}} is the other "chemical" [[sense]]. Unlike {{Wiki|taste}}, there are hundreds of {{Wiki|olfactory}} {{Wiki|receptors}} (388 according to one source), each binding to a particular {{Wiki|molecular}} feature. {{Wiki|Odor}} {{Wiki|molecules}} possess a variety of features and, thus, excite specific {{Wiki|receptors}} more or less strongly. This combination of {{Wiki|excitatory}} signals from different {{Wiki|receptors}} makes up what we {{Wiki|perceive}} as the molecule's {{Wiki|smell}}. In the {{Wiki|brain}}, {{Wiki|olfaction}} is processed by the {{Wiki|olfactory}} system. {{Wiki|Olfactory}} [[receptor]] {{Wiki|neurons}} in the {{Wiki|nose}} differ from most other {{Wiki|neurons}} in that they [[die]] and regenerate on a regular basis. The inability to {{Wiki|smell}} is called anosmia. Some {{Wiki|neurons}} in the {{Wiki|nose}} are specialized to detect {{Wiki|pheromones}}. | ||
− | + | ==== {{Wiki|Touch}} ==== | |
− | Touch | ||
− | '''Touch''' or somatosensory, also called tactition or mechanoreception, is a perception resulting from activation of neural receptors, generally in the skin including hair follicles, but also in the tongue, throat, and mucosa. A variety of pressure receptors respond to variations in pressure (firm, brushing, sustained, etc.). The touch sense of itching caused by insect bites or allergies involves special itch-specific neurons in the skin and spinal cord. The loss or impairment of the ability to feel anything touched is called tactile anesthesia. Paresthesia is a sensation of tingling, pricking, or numbness of the skin that may result from nerve damage and may be permanent or temporary. | + | '''{{Wiki|Touch}}''' or {{Wiki|somatosensory}}, also called {{Wiki|tactition}} or {{Wiki|mechanoreception}}, is a [[perception]] resulting from activation of neural {{Wiki|receptors}}, generally in the {{Wiki|skin}} including [[hair]] follicles, but also in the {{Wiki|tongue}}, {{Wiki|throat}}, and mucosa. A variety of pressure {{Wiki|receptors}} respond to variations in pressure (firm, brushing, sustained, etc.). The {{Wiki|touch}} [[sense]] of itching [[caused]] by insect bites or allergies involves special itch-specific {{Wiki|neurons}} in the {{Wiki|skin}} and {{Wiki|spinal cord}}. The loss or {{Wiki|impairment}} of the ability to [[feel]] anything touched is called {{Wiki|tactile}} {{Wiki|anesthesia}}. {{Wiki|Paresthesia}} is a [[sensation]] of tingling, pricking, or numbness of the {{Wiki|skin}} that may result from {{Wiki|nerve}} damage and may be [[permanent]] or temporary. |
{{W}} | {{W}} | ||
− | [[Category:Buddhist psychology]] | + | [[Category:Buddhist psychology]]{{BuddhismbyNumber}} |
Latest revision as of 11:07, 25 February 2015
Sight or vision is the capability of the eye(s) to focus and detect images of visible light on photoreceptors in the retina of each eye that generates electrical nerve impulses for varying colors, hues, and brightness. There are two types of photoreceptors: rods and cones. Rods are very sensitive to light, but do not distinguish colors. Cones distinguish colors, but are less sensitive to dim light. There is some disagreement as to whether this constitutes one, two or three senses. Neuroanatomists generally regard it as two senses, given that different receptors are responsible for the perception of color and brightness. Some argue that stereopsis, the perception of depth using both eyes, also constitutes a sense, but it is generally regarded as a cognitive (that is, post-sensory) function of the visual cortex of the brain where patterns and objects in images are recognized and interpreted based on previously learned information. This is called visual memory.
The inability to see is called blindness. Blindness may result from damage to the eyeball, especially to the retina, damage to the optic nerve that connects each eye to the brain, and/or from stroke (infarcts in the brain). Temporary or permanent blindness can be caused by poisons or medications.
People who are blind from degradation or damage to the visual cortex, but still have functional eyes, are actually capable of some level of vision and reaction to visual stimuli but not a conscious perception; this is known as blindsight. People with blindsight are usually not aware that they are reacting to visual sources, and instead just unconsciously adapt their behaviour to the stimulus.
Hearing
Hearing or audition is the sense of sound perception. Hearing is all about vibration. Mechanoreceptors turn motion into electrical nerve pulses, which are located in the inner ear. Since sound is vibrations propagating through a medium such as air, the detection of these vibrations, that is the sense of the hearing, is a mechanical sense because these vibrations are mechanically conducted from the eardrum through a series of tiny bones to hair-like fibers in the inner ear, which detect mechanical motion of the fibers within a range of about 20 to 20,000 hertz, with substantial variation between individuals. Hearing at high frequencies declines with an increase in age. Inability to hear is called deafness or hearing impairment. Sound can also be detected as vibrations conducted through the body by tactition. Lower frequencies than can be heard are detected this way.
Taste
Taste (or, the more formal term, gustation; adjectival form: "gustatory") is one of the traditional five senses. It refers to the capability to detect the taste of substances such as food, certain minerals, and poisons, etc. The sense of taste is often confused with the "sense" of flavor, which is a combination of taste and smell perception. Flavor depends on odor, texture, and temperature as well as on taste. Humans receive tastes through sensory organs called taste buds, or gustatory calyculi, concentrated on the upper surface of the tongue. There are five basic tastes: sweet, bitter, sour, salty and umami. Other tastes such as calcium and free fatty acids may be other basic tastes but have yet to receive widespread acceptance.
Smell
Smell or olfaction is the other "chemical" sense. Unlike taste, there are hundreds of olfactory receptors (388 according to one source), each binding to a particular molecular feature. Odor molecules possess a variety of features and, thus, excite specific receptors more or less strongly. This combination of excitatory signals from different receptors makes up what we perceive as the molecule's smell. In the brain, olfaction is processed by the olfactory system. Olfactory receptor neurons in the nose differ from most other neurons in that they die and regenerate on a regular basis. The inability to smell is called anosmia. Some neurons in the nose are specialized to detect pheromones.
Touch
Touch or somatosensory, also called tactition or mechanoreception, is a perception resulting from activation of neural receptors, generally in the skin including hair follicles, but also in the tongue, throat, and mucosa. A variety of pressure receptors respond to variations in pressure (firm, brushing, sustained, etc.). The touch sense of itching caused by insect bites or allergies involves special itch-specific neurons in the skin and spinal cord. The loss or impairment of the ability to feel anything touched is called tactile anesthesia. Paresthesia is a sensation of tingling, pricking, or numbness of the skin that may result from nerve damage and may be permanent or temporary.