{"id":120,"date":"2020-04-29T14:16:04","date_gmt":"2020-04-29T14:16:04","guid":{"rendered":"https:\/\/digitaleditions.library.dal.ca\/intropsychneuro\/?post_type=chapter&#038;p=120"},"modified":"2021-09-03T17:47:24","modified_gmt":"2021-09-03T17:47:24","slug":"the-other-senses","status":"publish","type":"chapter","link":"https:\/\/digitaleditions.library.dal.ca\/intropsychneuro\/chapter\/the-other-senses\/","title":{"raw":"The Other Senses","rendered":"The Other Senses"},"content":{"raw":"<div class=\"PageContent-ny9bj0-0 iapMdy\">\r\n<div id=\"main-content\" class=\"MainContent__HideOutline-sc-6yy1if-0 bdVAq\">\r\n<div id=\"86d07238-999a-4449-8e26-277086d7e224\">\r\n<div id=\"95755\" class=\"ui-has-child-title\"><header><\/header><section>\r\n<div class=\"textbox textbox--learning-objectives\"><header class=\"textbox__header\">\r\n<p class=\"textbox__title\"><span style=\"color: #ffffff\">Learning Objectives<\/span><\/p>\r\n\r\n<\/header>\r\n<div class=\"textbox__content\">\r\n\r\nBy the end of this section, you will be able to:\r\n<ul>\r\n \t<li>Describe the basic functions of the chemical senses<\/li>\r\n \t<li>Explain the basic functions of the somatosensory, nociceptive, and thermoceptive sensory systems<\/li>\r\n \t<li>Describe the basic functions of the vestibular, proprioceptive, and kinaesthetic sensory systems<\/li>\r\n<\/ul>\r\n<\/div>\r\n<\/div>\r\n<\/section><\/div>\r\n<p id=\"fs-idp8294224\">Vision and hearing have received an incredible amount of attention from researchers over the years. While there is still much to be learned about how these sensory systems work, we have a much better understanding of them than of our other sensory modalities. In this section, we will explore our chemical senses (taste and smell) and our body senses (touch, temperature, pain, balance, and body position).<\/p>\r\n\r\n<section id=\"fs-idp5987360\">\r\n<h3>The Chemical Senses<\/h3>\r\n<p id=\"fs-idp14287728\">Taste (gustation) and\u00a0<span id=\"term360\" class=\"no-emphasis\">smell<\/span>\u00a0(olfaction) are called chemical senses because both have sensory receptors that respond to molecules in the food we eat or in the air we breathe. There is a pronounced interaction between our chemical senses. For example, when we describe the flavour of a given food, we are really referring to both gustatory and olfactory properties of the food working in combination.<\/p>\r\n\r\n<section id=\"fs-idp64677872\">\r\n<h4>Taste (Gustation)<\/h4>\r\n<p id=\"fs-idp84168272\">You have learned since elementary school that there are four basic groupings of taste: sweet, salty, sour, and bitter. Research demonstrates, however, that we have at least six\u00a0<span id=\"term361\" class=\"no-emphasis\">taste<\/span>\u00a0groupings. Umami is our fifth taste.\u00a0<strong><span id=\"term362\">Umami<\/span>\u00a0<\/strong>is actually a Japanese word that roughly translates to yummy, and it is associated with a taste for monosodium glutamate (Kinnamon &amp; Vandenbeuch, 2009). There is also a growing body of experimental evidence suggesting that we possess a taste for the fatty content of a given food (Mizushige, Inoue, &amp; Fushiki, 2007).<\/p>\r\n<p id=\"fs-idm27095808\">Molecules from the food and beverages we consume dissolve in our saliva and interact with taste receptors on our tongue and in our mouth and throat.\u00a0<strong><span id=\"term363\">Taste buds<\/span><\/strong>\u00a0are formed by groupings of taste receptor cells with hair-like extensions that protrude into the central pore of the taste bud (<a class=\"autogenerated-content\" href=\"https:\/\/openstax.org\/books\/psychology-2e\/pages\/5-5-the-other-senses#Figure_05_05_TasteBud\">Figure SAP.22<\/a>). Taste buds have a life cycle of ten days to two weeks, so even destroying some by burning your tongue won\u2019t have any long-term effect; they just grow right back. Taste molecules bind to receptors on this extension and cause chemical changes within the sensory cell that result in neural impulses being transmitted to the brain via different nerves, depending on where the receptor is located. Taste information is transmitted to the medulla, thalamus, and limbic system, and to the gustatory cortex, which is tucked underneath the overlap between the frontal and temporal lobes (Maffei, Haley, &amp; Fontanini, 2012; Roper, 2013).<\/p>\r\n\r\n<div id=\"Figure_05_05_TasteBud\" class=\"os-figure\">\r\n<figure><\/figure>\r\n<div class=\"os-caption-container\">\r\n\r\n[caption id=\"attachment_1403\" align=\"aligncenter\" width=\"1024\"]<img class=\"wp-image-1403 size-large\" src=\"https:\/\/digitaleditions.library.dal.ca\/intropsychneuro\/wp-content\/uploads\/sites\/21\/2020\/04\/gustation-image-1024x434.jpg\" alt=\"Illustration A shows a taste bud in an opening of the tongue, with the \u201ctongue surface,\u201d \u201ctaste pore,\u201d \u201ctaste receptor cell\u201d and \u201cnerves\u201d labeled. Part B is a micrograph showing taste buds on a human tongue.\" width=\"1024\" height=\"434\" \/> Figure\u00a0SAP.22\u00a0(a) Taste buds are composed of a number of individual taste receptors cells that transmit information to nerves. (b) This micrograph shows a close-up view of the tongue\u2019s surface. (credit a: Molly Wells Art; credit b: scale-bar data from Matt Russell)[\/caption]\r\n\r\n<\/div>\r\n<\/div>\r\n<\/section><section id=\"fs-idp28646368\">\r\n<h4>Smell (Olfaction)<\/h4>\r\n<p id=\"fs-idm4091616\"><strong><span id=\"term364\">Olfactory receptor<\/span><\/strong>\u00a0cells are located in a mucous membrane at the top of the nose. Small hair-like extensions from these receptors serve as the sites for odour molecules dissolved in the mucus to interact with chemical receptors located on these extensions (<a class=\"autogenerated-content\" href=\"http:\/\/www.mollywellsart.ca\/scientific-illustration.html\">Figure SAP.23<\/a>). Once an odour molecule has bound a given receptor, chemical changes within the cell result in signals being sent to the\u00a0<strong><span id=\"term365\">olfactory bulb<\/span><\/strong>: a bulb-like structure at the tip of the frontal lobe where the olfactory nerves begin. From the olfactory bulb, information is sent to regions of the limbic system and to the primary olfactory cortex, which is located very near the gustatory cortex (Lodovichi &amp; Belluscio, 2012; Spors et al., 2013).<\/p>\r\n\r\n<div id=\"Figure_05_05_OlfacRecep\" class=\"os-figure\">\r\n<figure><\/figure>\r\n<div class=\"os-caption-container\">\r\n\r\n[caption id=\"attachment_1404\" align=\"aligncenter\" width=\"300\"]<img class=\"wp-image-1404 size-medium\" src=\"https:\/\/digitaleditions.library.dal.ca\/intropsychneuro\/wp-content\/uploads\/sites\/21\/2020\/04\/olfaction-image-300x285.jpg\" alt=\"An illustration shows a side view of a human head and the location of the \u201cnasal cavity,\u201d \u201colfactory receptors,\u201d and \u201colfactory bulb.\u201d\" width=\"300\" height=\"285\" \/> Figure\u00a0SAP.23\u00a0Olfactory receptors are the hair-like parts that extend from the olfactory bulb into the mucous membrane of the nasal cavity. (credit: <a href=\"http:\/\/www.mollywellsart.ca\/scientific-illustration.html\">Molly Wells Ar<\/a>t)[\/caption]\r\n\r\n<\/div>\r\n<\/div>\r\n<p id=\"fs-idm21753600\">There is tremendous variation in the sensitivity of the olfactory systems of different species. We often think of dogs as having far superior olfactory systems than our own, and indeed, dogs can do some remarkable things with their noses. There is some evidence to suggest that dogs can \u201csmell\u201d dangerous drops in blood glucose levels as well as cancerous tumours (Wells, 2010). Dogs\u2019 extraordinary olfactory abilities may be due to the increased number of functional genes for olfactory receptors (between 800 and 1200), compared to the fewer than 400 observed in humans and other primates (Niimura &amp; Nei, 2007).<\/p>\r\n<p id=\"fs-idp109938928\">Many species respond to chemical messages, known as\u00a0<strong><span id=\"term366\">pheromones<\/span><\/strong>, sent by another individual (Wysocki &amp; Preti, 2004). Pheromonal communication often involves providing information about the reproductive status of a potential mate. So, for example, when a female rat is ready to mate, she secretes pheromonal signals that draw attention from nearby male rats. Pheromonal activation is actually an important component in eliciting sexual behaviour in the male rat (Furlow, 1996, 2012; Purvis &amp; Haynes, 1972; Sachs, 1997). There has also been a good deal of research (and controversy) about pheromones in humans (Comfort, 1971; Russell, 1976; Wolfgang-Kimball, 1992; Weller, 1998).<\/p>\r\n\r\n<\/section><\/section><section id=\"fs-idp7757872\">\r\n<h3>Touch, Thermoception, and Nociception<\/h3>\r\n<p id=\"fs-idp11691024\">A number of receptors are distributed throughout the skin to respond to various touch-related stimuli (<a class=\"autogenerated-content\" href=\"https:\/\/openstax.org\/books\/psychology-2e\/pages\/5-5-the-other-senses#Figure_05_05_Touch\">Figure SAP.24<\/a>). These receptors include Meissner\u2019s corpuscles, Pacinian corpuscles, Merkel\u2019s disks, and Ruffini corpuscles.\u00a0<strong><span id=\"term367\">Meissner\u2019s corpuscles<\/span><\/strong>\u00a0respond to pressure and lower frequency vibrations, and\u00a0<strong><span id=\"term368\">Pacinian corpuscles<\/span>\u00a0<\/strong>detect transient pressure and higher frequency vibrations.\u00a0<strong><span id=\"term369\">Merkel\u2019s disks<\/span><\/strong>\u00a0respond to light pressure, while\u00a0<strong><span id=\"term370\">Ruffini corpuscles<\/span><\/strong>\u00a0detect stretch (Abraira &amp; Ginty, 2013).<\/p>\r\n\r\n<div id=\"Figure_05_05_Touch\" class=\"os-figure\">\r\n<figure>\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"557\"]<img id=\"66666\" src=\"https:\/\/openstax.org\/resources\/be269ed61f5259c5fd4b92c698ccaa4092379c26\" alt=\"An illustration shows \u201cskin surface\u201d underneath which different receptors are identified: the \u201cpacinian corpuscle,\u201d \u201cruffini corpuscle,\u201d \u201cmerkel\u2019s disk,\u201d and \u201cmeissner\u2019s corpuscle.\u201d\" width=\"557\" height=\"312\" \/> Figure\u00a0SAP.24\u00a0There are many types of sensory receptors located in the skin, each attuned to specific touch-related stimuli.[\/caption]<\/figure>\r\n<p class=\"os-caption-container\"><span style=\"text-align: initial;font-size: 1em\">In addition to the receptors located in the skin, there are also a number of free nerve endings that serve sensory functions. These nerve endings respond to a variety of different types of touch-related stimuli and serve as sensory receptors for both<\/span><strong style=\"text-align: initial;font-size: 1em\">\u00a0<span id=\"term371\">thermoception<\/span><\/strong><span style=\"text-align: initial;font-size: 1em\">\u00a0(temperature perception) and\u00a0<\/span><strong style=\"text-align: initial;font-size: 1em\"><span id=\"term372\">nociception<\/span>\u00a0<\/strong><span style=\"text-align: initial;font-size: 1em\">(a signal indicating potential harm and maybe pain) (Garland, 2012; Petho &amp; Reeh, 2012; Spray, 1986). Sensory information collected from the receptors and free nerve endings travels up the spinal cord and is transmitted to regions of the medulla, thalamus, and ultimately to somatosensory cortex, which is located in the postcentral gyrus of the parietal lobe.<\/span><\/p>\r\n\r\n<\/div>\r\n<section id=\"fs-idm12779248\">\r\n<h4>Pain Perception<\/h4>\r\n<p id=\"fs-idm76055408\">Pain is an unpleasant experience that involves both physical and psychological components. Feeling pain is quite adaptive because it makes us aware of an injury, and it motivates us to remove ourselves from the cause of that injury. In addition, pain also makes us less likely to suffer additional injury because we will be gentler with our injured body parts.<\/p>\r\n<p id=\"fs-idm78395840\">Generally speaking, pain can be considered to be neuropathic or inflammatory in nature. Pain that signals some type of tissue damage is known as\u00a0<strong><span id=\"term373\">inflammatory pain<\/span><\/strong>. In some situations, pain results from damage to neurones of either the peripheral or central nervous system. As a result, pain signals that are sent to the brain get exaggerated. This type of pain is known as\u00a0<strong><span id=\"term374\">neuropathic pain<\/span><\/strong>. Multiple treatment options for pain relief range from relaxation therapy to the use of analgesic medications to deep brain stimulation. The most effective treatment option for a given individual will depend on a number of considerations, including the severity and persistence of the pain and any medical\/psychological conditions.<\/p>\r\n<p id=\"fs-idm28421280\">Some individuals are born without the ability to feel pain. This very rare genetic disorder is known as\u00a0<span id=\"term375\"><strong>congenital insensitivity to pain<\/strong>\u00a0<\/span>(or\u00a0<strong><span id=\"term376\">congenital analgesia<\/span><\/strong>). While those with congenital analgesia can detect differences in temperature and pressure, they cannot experience pain. As a result, they often suffer significant injuries. Young children have serious mouth and tongue injuries because they have bitten themselves repeatedly. Not surprisingly, individuals suffering from this disorder have much shorter life expectancies due to their injuries and secondary infections of injured sites (U.S. National Library of Medicine, 2013).<\/p>\r\n\r\n<div id=\"fs-idp4560560\" class=\"psychology link-to-learning ui-has-child-title\"><header>\r\n<div class=\"textbox textbox--key-takeaways\"><header class=\"textbox__header\">\r\n<p class=\"textbox__title\"><span style=\"color: #ffffff\">LINK TO LEARNING<\/span><\/p>\r\n\r\n<\/header>\r\n<div class=\"textbox__content\"><span style=\"text-align: initial;font-family: Lora, serif;font-size: 1em;font-weight: normal\">Watch this\u00a0<\/span><a style=\"text-align: initial;font-family: Lora, serif;font-size: 1em;font-weight: normal\" href=\"http:\/\/openstax.org\/l\/congenital\" target=\"_blank\" rel=\"noopener nofollow\">video about congenital insensitivity to pain<\/a><span style=\"text-align: initial;font-family: Lora, serif;font-size: 1em;font-weight: normal\">\u00a0to learn more.<\/span><\/div>\r\n<\/div>\r\n<\/header><\/div>\r\n<\/section><\/section><section id=\"fs-idm12760480\">\r\n<h3>The Vestibular Sense, Proprioception, and Kinaesthesia<\/h3>\r\n<p id=\"fs-idp105592464\">The<strong>\u00a0<span id=\"term377\">vestibular sense<\/span><\/strong>\u00a0contributes to our ability to maintain balance and body posture. As\u00a0<a class=\"autogenerated-content\" href=\"https:\/\/openstax.org\/books\/psychology-2e\/pages\/5-5-the-other-senses#Figure_05_05_Vestibular\">Figure SAP.25<\/a>\u00a0shows, the major sensory organs (utricle, saccule, and the three semicircular canals) of this system are located next to the cochlea in the inner ear. The vestibular organs are fluid-filled and have hair cells, similar to the ones found in the auditory system, which respond to movement of the head and gravitational forces. When these hair cells are stimulated, they send signals to the brain via the vestibular nerve. Although we may not be consciously aware of our vestibular system\u2019s sensory information under normal circumstances, its importance is apparent when we experience motion sickness and\/or dizziness related to infections of the inner ear (Khan &amp; Chang, 2013).<\/p>\r\n\r\n<div id=\"Figure_05_05_Vestibular\" class=\"os-figure\">\r\n<figure>\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"487\"]<img id=\"1724\" src=\"https:\/\/openstax.org\/resources\/29174d2264cd4998b64b8dcf82fe2c1ec3eff673\" alt=\"An illustration of the vestibular system shows the locations of the three canals (\u201cposterior canal,\u201d \u201chorizontal canal,\u201d and \u201csuperior canal\u201d) and the locations of the \u201curticle,\u201d \u201coval window,\u201d \u201ccochlea,\u201d \u201cbasilar membrane and hair cells,\u201d \u201csaccule,\u201d and \u201cvestibule.\u201d\" width=\"487\" height=\"425\" \/> Figure\u00a0SAP.25\u00a0The major sensory organs of the vestibular system are located next to the cochlea in the inner ear. These include the utricle, saccule, and the three semicircular canals (posterior, superior, and horizontal).[\/caption]<\/figure>\r\n<\/div>\r\n<p id=\"fs-idm23066208\">In addition to maintaining balance, the vestibular system collects information critical for controlling movement and the reflexes that move various parts of our bodies to compensate for changes in body position. Therefore, both<strong>\u00a0<\/strong><span id=\"term378\"><strong>proprioception<\/strong>\u00a0<\/span>(perception of body position) and\u00a0<span id=\"term379\"><b>kinaesthesia\u00a0<\/b><\/span>(perception of the body\u2019s movement through space) interact with information provided by the vestibular system.<\/p>\r\n<p id=\"fs-idp80383424\">These sensory systems also gather information from receptors that respond to stretch and tension in muscles, joints, skin, and tendons (Lackner &amp; DiZio, 2005; Proske, 2006; Proske &amp; Gandevia, 2012). Proprioceptive and kinaesthetic information travels to the brain via the spinal column. Several cortical regions in addition to the cerebellum receive information from and send information to the sensory organs of the proprioceptive and kinaesthetic systems.<\/p>\r\n\r\n<\/section><\/div>\r\n<\/div>\r\n<\/div>","rendered":"<div class=\"PageContent-ny9bj0-0 iapMdy\">\n<div id=\"main-content\" class=\"MainContent__HideOutline-sc-6yy1if-0 bdVAq\">\n<div id=\"86d07238-999a-4449-8e26-277086d7e224\">\n<div id=\"95755\" class=\"ui-has-child-title\">\n<header><\/header>\n<section>\n<div class=\"textbox textbox--learning-objectives\">\n<header class=\"textbox__header\">\n<p class=\"textbox__title\"><span style=\"color: #ffffff\">Learning Objectives<\/span><\/p>\n<\/header>\n<div class=\"textbox__content\">\n<p>By the end of this section, you will be able to:<\/p>\n<ul>\n<li>Describe the basic functions of the chemical senses<\/li>\n<li>Explain the basic functions of the somatosensory, nociceptive, and thermoceptive sensory systems<\/li>\n<li>Describe the basic functions of the vestibular, proprioceptive, and kinaesthetic sensory systems<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<\/section>\n<\/div>\n<p id=\"fs-idp8294224\">Vision and hearing have received an incredible amount of attention from researchers over the years. While there is still much to be learned about how these sensory systems work, we have a much better understanding of them than of our other sensory modalities. In this section, we will explore our chemical senses (taste and smell) and our body senses (touch, temperature, pain, balance, and body position).<\/p>\n<section id=\"fs-idp5987360\">\n<h3>The Chemical Senses<\/h3>\n<p id=\"fs-idp14287728\">Taste (gustation) and\u00a0<span id=\"term360\" class=\"no-emphasis\">smell<\/span>\u00a0(olfaction) are called chemical senses because both have sensory receptors that respond to molecules in the food we eat or in the air we breathe. There is a pronounced interaction between our chemical senses. For example, when we describe the flavour of a given food, we are really referring to both gustatory and olfactory properties of the food working in combination.<\/p>\n<section id=\"fs-idp64677872\">\n<h4>Taste (Gustation)<\/h4>\n<p id=\"fs-idp84168272\">You have learned since elementary school that there are four basic groupings of taste: sweet, salty, sour, and bitter. Research demonstrates, however, that we have at least six\u00a0<span id=\"term361\" class=\"no-emphasis\">taste<\/span>\u00a0groupings. Umami is our fifth taste.\u00a0<strong><span id=\"term362\">Umami<\/span>\u00a0<\/strong>is actually a Japanese word that roughly translates to yummy, and it is associated with a taste for monosodium glutamate (Kinnamon &amp; Vandenbeuch, 2009). There is also a growing body of experimental evidence suggesting that we possess a taste for the fatty content of a given food (Mizushige, Inoue, &amp; Fushiki, 2007).<\/p>\n<p id=\"fs-idm27095808\">Molecules from the food and beverages we consume dissolve in our saliva and interact with taste receptors on our tongue and in our mouth and throat.\u00a0<strong><span id=\"term363\">Taste buds<\/span><\/strong>\u00a0are formed by groupings of taste receptor cells with hair-like extensions that protrude into the central pore of the taste bud (<a class=\"autogenerated-content\" href=\"https:\/\/openstax.org\/books\/psychology-2e\/pages\/5-5-the-other-senses#Figure_05_05_TasteBud\">Figure SAP.22<\/a>). Taste buds have a life cycle of ten days to two weeks, so even destroying some by burning your tongue won\u2019t have any long-term effect; they just grow right back. Taste molecules bind to receptors on this extension and cause chemical changes within the sensory cell that result in neural impulses being transmitted to the brain via different nerves, depending on where the receptor is located. Taste information is transmitted to the medulla, thalamus, and limbic system, and to the gustatory cortex, which is tucked underneath the overlap between the frontal and temporal lobes (Maffei, Haley, &amp; Fontanini, 2012; Roper, 2013).<\/p>\n<div id=\"Figure_05_05_TasteBud\" class=\"os-figure\">\n<figure><\/figure>\n<div class=\"os-caption-container\">\n<figure id=\"attachment_1403\" aria-describedby=\"caption-attachment-1403\" style=\"width: 1024px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-1403 size-large\" src=\"https:\/\/digitaleditions.library.dal.ca\/intropsychneuro\/wp-content\/uploads\/sites\/21\/2020\/04\/gustation-image-1024x434.jpg\" alt=\"Illustration A shows a taste bud in an opening of the tongue, with the \u201ctongue surface,\u201d \u201ctaste pore,\u201d \u201ctaste receptor cell\u201d and \u201cnerves\u201d labeled. Part B is a micrograph showing taste buds on a human tongue.\" width=\"1024\" height=\"434\" srcset=\"https:\/\/digitaleditions.library.dal.ca\/intropsychneuro\/wp-content\/uploads\/sites\/21\/2020\/04\/gustation-image-1024x434.jpg 1024w, https:\/\/digitaleditions.library.dal.ca\/intropsychneuro\/wp-content\/uploads\/sites\/21\/2020\/04\/gustation-image-300x127.jpg 300w, https:\/\/digitaleditions.library.dal.ca\/intropsychneuro\/wp-content\/uploads\/sites\/21\/2020\/04\/gustation-image-768x325.jpg 768w, https:\/\/digitaleditions.library.dal.ca\/intropsychneuro\/wp-content\/uploads\/sites\/21\/2020\/04\/gustation-image-65x28.jpg 65w, https:\/\/digitaleditions.library.dal.ca\/intropsychneuro\/wp-content\/uploads\/sites\/21\/2020\/04\/gustation-image-225x95.jpg 225w, https:\/\/digitaleditions.library.dal.ca\/intropsychneuro\/wp-content\/uploads\/sites\/21\/2020\/04\/gustation-image-350x148.jpg 350w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><figcaption id=\"caption-attachment-1403\" class=\"wp-caption-text\">Figure\u00a0SAP.22\u00a0(a) Taste buds are composed of a number of individual taste receptors cells that transmit information to nerves. (b) This micrograph shows a close-up view of the tongue\u2019s surface. (credit a: Molly Wells Art; credit b: scale-bar data from Matt Russell)<\/figcaption><\/figure>\n<\/div>\n<\/div>\n<\/section>\n<section id=\"fs-idp28646368\">\n<h4>Smell (Olfaction)<\/h4>\n<p id=\"fs-idm4091616\"><strong><span id=\"term364\">Olfactory receptor<\/span><\/strong>\u00a0cells are located in a mucous membrane at the top of the nose. Small hair-like extensions from these receptors serve as the sites for odour molecules dissolved in the mucus to interact with chemical receptors located on these extensions (<a class=\"autogenerated-content\" href=\"http:\/\/www.mollywellsart.ca\/scientific-illustration.html\">Figure SAP.23<\/a>). Once an odour molecule has bound a given receptor, chemical changes within the cell result in signals being sent to the\u00a0<strong><span id=\"term365\">olfactory bulb<\/span><\/strong>: a bulb-like structure at the tip of the frontal lobe where the olfactory nerves begin. From the olfactory bulb, information is sent to regions of the limbic system and to the primary olfactory cortex, which is located very near the gustatory cortex (Lodovichi &amp; Belluscio, 2012; Spors et al., 2013).<\/p>\n<div id=\"Figure_05_05_OlfacRecep\" class=\"os-figure\">\n<figure><\/figure>\n<div class=\"os-caption-container\">\n<figure id=\"attachment_1404\" aria-describedby=\"caption-attachment-1404\" style=\"width: 300px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-1404 size-medium\" src=\"https:\/\/digitaleditions.library.dal.ca\/intropsychneuro\/wp-content\/uploads\/sites\/21\/2020\/04\/olfaction-image-300x285.jpg\" alt=\"An illustration shows a side view of a human head and the location of the \u201cnasal cavity,\u201d \u201colfactory receptors,\u201d and \u201colfactory bulb.\u201d\" width=\"300\" height=\"285\" srcset=\"https:\/\/digitaleditions.library.dal.ca\/intropsychneuro\/wp-content\/uploads\/sites\/21\/2020\/04\/olfaction-image-300x285.jpg 300w, https:\/\/digitaleditions.library.dal.ca\/intropsychneuro\/wp-content\/uploads\/sites\/21\/2020\/04\/olfaction-image-768x728.jpg 768w, https:\/\/digitaleditions.library.dal.ca\/intropsychneuro\/wp-content\/uploads\/sites\/21\/2020\/04\/olfaction-image-1024x971.jpg 1024w, https:\/\/digitaleditions.library.dal.ca\/intropsychneuro\/wp-content\/uploads\/sites\/21\/2020\/04\/olfaction-image-65x62.jpg 65w, https:\/\/digitaleditions.library.dal.ca\/intropsychneuro\/wp-content\/uploads\/sites\/21\/2020\/04\/olfaction-image-225x213.jpg 225w, https:\/\/digitaleditions.library.dal.ca\/intropsychneuro\/wp-content\/uploads\/sites\/21\/2020\/04\/olfaction-image-350x332.jpg 350w\" sizes=\"(max-width: 300px) 100vw, 300px\" \/><figcaption id=\"caption-attachment-1404\" class=\"wp-caption-text\">Figure\u00a0SAP.23\u00a0Olfactory receptors are the hair-like parts that extend from the olfactory bulb into the mucous membrane of the nasal cavity. (credit: <a href=\"http:\/\/www.mollywellsart.ca\/scientific-illustration.html\">Molly Wells Ar<\/a>t)<\/figcaption><\/figure>\n<\/div>\n<\/div>\n<p id=\"fs-idm21753600\">There is tremendous variation in the sensitivity of the olfactory systems of different species. We often think of dogs as having far superior olfactory systems than our own, and indeed, dogs can do some remarkable things with their noses. There is some evidence to suggest that dogs can \u201csmell\u201d dangerous drops in blood glucose levels as well as cancerous tumours (Wells, 2010). Dogs\u2019 extraordinary olfactory abilities may be due to the increased number of functional genes for olfactory receptors (between 800 and 1200), compared to the fewer than 400 observed in humans and other primates (Niimura &amp; Nei, 2007).<\/p>\n<p id=\"fs-idp109938928\">Many species respond to chemical messages, known as\u00a0<strong><span id=\"term366\">pheromones<\/span><\/strong>, sent by another individual (Wysocki &amp; Preti, 2004). Pheromonal communication often involves providing information about the reproductive status of a potential mate. So, for example, when a female rat is ready to mate, she secretes pheromonal signals that draw attention from nearby male rats. Pheromonal activation is actually an important component in eliciting sexual behaviour in the male rat (Furlow, 1996, 2012; Purvis &amp; Haynes, 1972; Sachs, 1997). There has also been a good deal of research (and controversy) about pheromones in humans (Comfort, 1971; Russell, 1976; Wolfgang-Kimball, 1992; Weller, 1998).<\/p>\n<\/section>\n<\/section>\n<section id=\"fs-idp7757872\">\n<h3>Touch, Thermoception, and Nociception<\/h3>\n<p id=\"fs-idp11691024\">A number of receptors are distributed throughout the skin to respond to various touch-related stimuli (<a class=\"autogenerated-content\" href=\"https:\/\/openstax.org\/books\/psychology-2e\/pages\/5-5-the-other-senses#Figure_05_05_Touch\">Figure SAP.24<\/a>). These receptors include Meissner\u2019s corpuscles, Pacinian corpuscles, Merkel\u2019s disks, and Ruffini corpuscles.\u00a0<strong><span id=\"term367\">Meissner\u2019s corpuscles<\/span><\/strong>\u00a0respond to pressure and lower frequency vibrations, and\u00a0<strong><span id=\"term368\">Pacinian corpuscles<\/span>\u00a0<\/strong>detect transient pressure and higher frequency vibrations.\u00a0<strong><span id=\"term369\">Merkel\u2019s disks<\/span><\/strong>\u00a0respond to light pressure, while\u00a0<strong><span id=\"term370\">Ruffini corpuscles<\/span><\/strong>\u00a0detect stretch (Abraira &amp; Ginty, 2013).<\/p>\n<div id=\"Figure_05_05_Touch\" class=\"os-figure\">\n<figure>\n<figure style=\"width: 557px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" id=\"66666\" src=\"https:\/\/openstax.org\/resources\/be269ed61f5259c5fd4b92c698ccaa4092379c26\" alt=\"An illustration shows \u201cskin surface\u201d underneath which different receptors are identified: the \u201cpacinian corpuscle,\u201d \u201cruffini corpuscle,\u201d \u201cmerkel\u2019s disk,\u201d and \u201cmeissner\u2019s corpuscle.\u201d\" width=\"557\" height=\"312\" \/><figcaption class=\"wp-caption-text\">Figure\u00a0SAP.24\u00a0There are many types of sensory receptors located in the skin, each attuned to specific touch-related stimuli.<\/figcaption><\/figure>\n<\/figure>\n<p class=\"os-caption-container\"><span style=\"text-align: initial;font-size: 1em\">In addition to the receptors located in the skin, there are also a number of free nerve endings that serve sensory functions. These nerve endings respond to a variety of different types of touch-related stimuli and serve as sensory receptors for both<\/span><strong style=\"text-align: initial;font-size: 1em\">\u00a0<span id=\"term371\">thermoception<\/span><\/strong><span style=\"text-align: initial;font-size: 1em\">\u00a0(temperature perception) and\u00a0<\/span><strong style=\"text-align: initial;font-size: 1em\"><span id=\"term372\">nociception<\/span>\u00a0<\/strong><span style=\"text-align: initial;font-size: 1em\">(a signal indicating potential harm and maybe pain) (Garland, 2012; Petho &amp; Reeh, 2012; Spray, 1986). Sensory information collected from the receptors and free nerve endings travels up the spinal cord and is transmitted to regions of the medulla, thalamus, and ultimately to somatosensory cortex, which is located in the postcentral gyrus of the parietal lobe.<\/span><\/p>\n<\/div>\n<section id=\"fs-idm12779248\">\n<h4>Pain Perception<\/h4>\n<p id=\"fs-idm76055408\">Pain is an unpleasant experience that involves both physical and psychological components. Feeling pain is quite adaptive because it makes us aware of an injury, and it motivates us to remove ourselves from the cause of that injury. In addition, pain also makes us less likely to suffer additional injury because we will be gentler with our injured body parts.<\/p>\n<p id=\"fs-idm78395840\">Generally speaking, pain can be considered to be neuropathic or inflammatory in nature. Pain that signals some type of tissue damage is known as\u00a0<strong><span id=\"term373\">inflammatory pain<\/span><\/strong>. In some situations, pain results from damage to neurones of either the peripheral or central nervous system. As a result, pain signals that are sent to the brain get exaggerated. This type of pain is known as\u00a0<strong><span id=\"term374\">neuropathic pain<\/span><\/strong>. Multiple treatment options for pain relief range from relaxation therapy to the use of analgesic medications to deep brain stimulation. The most effective treatment option for a given individual will depend on a number of considerations, including the severity and persistence of the pain and any medical\/psychological conditions.<\/p>\n<p id=\"fs-idm28421280\">Some individuals are born without the ability to feel pain. This very rare genetic disorder is known as\u00a0<span id=\"term375\"><strong>congenital insensitivity to pain<\/strong>\u00a0<\/span>(or\u00a0<strong><span id=\"term376\">congenital analgesia<\/span><\/strong>). While those with congenital analgesia can detect differences in temperature and pressure, they cannot experience pain. As a result, they often suffer significant injuries. Young children have serious mouth and tongue injuries because they have bitten themselves repeatedly. Not surprisingly, individuals suffering from this disorder have much shorter life expectancies due to their injuries and secondary infections of injured sites (U.S. National Library of Medicine, 2013).<\/p>\n<div id=\"fs-idp4560560\" class=\"psychology link-to-learning ui-has-child-title\">\n<header>\n<div class=\"textbox textbox--key-takeaways\"><\/div>\n<\/header>\n<header class=\"textbox__header\">\n<p class=\"textbox__title\"><span style=\"color: #ffffff\">LINK TO LEARNING<\/span><\/p>\n<\/header>\n<div class=\"textbox__content\"><span style=\"text-align: initial;font-family: Lora, serif;font-size: 1em;font-weight: normal\">Watch this\u00a0<\/span><a style=\"text-align: initial;font-family: Lora, serif;font-size: 1em;font-weight: normal\" href=\"http:\/\/openstax.org\/l\/congenital\" target=\"_blank\" rel=\"noopener nofollow\">video about congenital insensitivity to pain<\/a><span style=\"text-align: initial;font-family: Lora, serif;font-size: 1em;font-weight: normal\">\u00a0to learn more.<\/span><\/div>\n<\/div>\n<\/section>\n<\/section>\n<\/div>\n<section id=\"fs-idm12760480\">\n<h3>The Vestibular Sense, Proprioception, and Kinaesthesia<\/h3>\n<p id=\"fs-idp105592464\">The<strong>\u00a0<span id=\"term377\">vestibular sense<\/span><\/strong>\u00a0contributes to our ability to maintain balance and body posture. As\u00a0<a class=\"autogenerated-content\" href=\"https:\/\/openstax.org\/books\/psychology-2e\/pages\/5-5-the-other-senses#Figure_05_05_Vestibular\">Figure SAP.25<\/a>\u00a0shows, the major sensory organs (utricle, saccule, and the three semicircular canals) of this system are located next to the cochlea in the inner ear. The vestibular organs are fluid-filled and have hair cells, similar to the ones found in the auditory system, which respond to movement of the head and gravitational forces. When these hair cells are stimulated, they send signals to the brain via the vestibular nerve. Although we may not be consciously aware of our vestibular system\u2019s sensory information under normal circumstances, its importance is apparent when we experience motion sickness and\/or dizziness related to infections of the inner ear (Khan &amp; Chang, 2013).<\/p>\n<div id=\"Figure_05_05_Vestibular\" class=\"os-figure\">\n<figure>\n<figure style=\"width: 487px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" id=\"1724\" src=\"https:\/\/openstax.org\/resources\/29174d2264cd4998b64b8dcf82fe2c1ec3eff673\" alt=\"An illustration of the vestibular system shows the locations of the three canals (\u201cposterior canal,\u201d \u201chorizontal canal,\u201d and \u201csuperior canal\u201d) and the locations of the \u201curticle,\u201d \u201coval window,\u201d \u201ccochlea,\u201d \u201cbasilar membrane and hair cells,\u201d \u201csaccule,\u201d and \u201cvestibule.\u201d\" width=\"487\" height=\"425\" \/><figcaption class=\"wp-caption-text\">Figure\u00a0SAP.25\u00a0The major sensory organs of the vestibular system are located next to the cochlea in the inner ear. These include the utricle, saccule, and the three semicircular canals (posterior, superior, and horizontal).<\/figcaption><\/figure>\n<\/figure>\n<\/div>\n<p id=\"fs-idm23066208\">In addition to maintaining balance, the vestibular system collects information critical for controlling movement and the reflexes that move various parts of our bodies to compensate for changes in body position. Therefore, both<strong>\u00a0<\/strong><span id=\"term378\"><strong>proprioception<\/strong>\u00a0<\/span>(perception of body position) and\u00a0<span id=\"term379\"><b>kinaesthesia\u00a0<\/b><\/span>(perception of the body\u2019s movement through space) interact with information provided by the vestibular system.<\/p>\n<p id=\"fs-idp80383424\">These sensory systems also gather information from receptors that respond to stretch and tension in muscles, joints, skin, and tendons (Lackner &amp; DiZio, 2005; Proske, 2006; Proske &amp; Gandevia, 2012). Proprioceptive and kinaesthetic information travels to the brain via the spinal column. Several cortical regions in addition to the cerebellum receive information from and send information to the sensory organs of the proprioceptive and kinaesthetic systems.<\/p>\n<\/section>\n<\/div>\n<\/div>\n","protected":false},"author":13,"menu_order":9,"template":"","meta":{"pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[],"contributor":[],"license":[],"part":27,"_links":{"self":[{"href":"https:\/\/digitaleditions.library.dal.ca\/intropsychneuro\/wp-json\/pressbooks\/v2\/chapters\/120"}],"collection":[{"href":"https:\/\/digitaleditions.library.dal.ca\/intropsychneuro\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/digitaleditions.library.dal.ca\/intropsychneuro\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/digitaleditions.library.dal.ca\/intropsychneuro\/wp-json\/wp\/v2\/users\/13"}],"version-history":[{"count":11,"href":"https:\/\/digitaleditions.library.dal.ca\/intropsychneuro\/wp-json\/pressbooks\/v2\/chapters\/120\/revisions"}],"predecessor-version":[{"id":2072,"href":"https:\/\/digitaleditions.library.dal.ca\/intropsychneuro\/wp-json\/pressbooks\/v2\/chapters\/120\/revisions\/2072"}],"part":[{"href":"https:\/\/digitaleditions.library.dal.ca\/intropsychneuro\/wp-json\/pressbooks\/v2\/parts\/27"}],"metadata":[{"href":"https:\/\/digitaleditions.library.dal.ca\/intropsychneuro\/wp-json\/pressbooks\/v2\/chapters\/120\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/digitaleditions.library.dal.ca\/intropsychneuro\/wp-json\/wp\/v2\/media?parent=120"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/digitaleditions.library.dal.ca\/intropsychneuro\/wp-json\/pressbooks\/v2\/chapter-type?post=120"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/digitaleditions.library.dal.ca\/intropsychneuro\/wp-json\/wp\/v2\/contributor?post=120"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/digitaleditions.library.dal.ca\/intropsychneuro\/wp-json\/wp\/v2\/license?post=120"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}