What Is the Peripheral Nervous System?<\/h1>\r\n<\/div>\r\nThe\u00a0[pb_glossary id=\"3009\"]peripheral nervous system[\/pb_glossary] (PNS)<\/strong>\u00a0consists of all the nervous tissue that lies outside of the\u00a0[pb_glossary id=\"5933\"]central nervous system[\/pb_glossary]\u00a0(CNS). The main function of the PNS is to connect the CNS to the rest of the organism. It serves as a\u00a0communication\u00a0relay, going back and forth between the CNS and\u00a0muscles, organs, and glands throughout the body.\r\n\r\n[caption id=\"attachment_3107\" align=\"aligncenter\" width=\"421\"]![\"Peripheral](\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2023\/10\/Nervous_system_diagram-2.png\")
Figure 8.6.2 The nerves of the peripheral nervous system are shown in blue in this diagram.<\/em>[\/caption]\r\n\r\n<\/div>\r\n\r\nTissues of the Peripheral Nervous System<\/h1>\r\n<\/div>\r\nThe PNS is mostly made up of cable-like bundles of axons called\u00a0[pb_glossary id=\"3011\"]nerves[\/pb_glossary]<\/strong>,\u00a0as well as\u00a0clusters of neuronal cell bodies called\u00a0[pb_glossary id=\"6027\"]ganglia[\/pb_glossary]<\/strong>\u00a0(singular,\u00a0[pb_glossary id=\"6029\"]ganglion[\/pb_glossary]<\/strong>). Nerves are generally classified\u00a0as sensory, motor, or mixed nerves\u00a0based on\u00a0the direction in which they carry\u00a0nerve impulses.\r\n\r\n \t- [pb_glossary id=\"3110\"]Sensory nerves[\/pb_glossary]<\/strong>\u00a0transmit information from sensory receptors in the body to the CNS. Sensory nerves are also called afferent nerves. You can see an example in the figure\u00a0below.<\/li>\r\n \t
- [pb_glossary id=\"3111\"]Motor nerves[\/pb_glossary]<\/strong>\u00a0transmit information from the CNS to\u00a0muscles, organs, and glands. Motor nerves are also called efferent nerves. You can see one in the figure\u00a0below.<\/li>\r\n \t
- [pb_glossary id=\"3112\"]Mixed nerves[\/pb_glossary]<\/strong>\u00a0contain both sensory and motor neurons, so they can transmit information in both directions. They have both afferent and efferent functions.<\/li>\r\n<\/ul>\r\n \r\n\r\n\r\n[caption id=\"attachment_3113\" align=\"aligncenter\" width=\"868\"]
![\"Afferent](\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2023\/10\/Afferent_and_efferent_neurons_en.svg_-2.png\")
Figure 8.6.3 In this diagram, each nerve is depicted as a single neuron for simplicity. This afferent neuron sends nerve impulses from sensory receptors in the skin to the CNS. The efferent neuron is a motor neuron that sends nerve impulses from the CNS to a muscle. The cell body of the afferent neuron is located in a ganglion (not pictured), while the cell body of the motor neuron is located in the spinal cord.<\/em>[\/caption]\r\n\r\n<\/div>\r\n\r\nDivisions of the Peripheral Nervous System<\/h1>\r\n<\/div>\r\nThe PNS is divided into two major systems, called the [pb_glossary id=\"5899\"]autonomic nervous system[\/pb_glossary] and the [pb_glossary id=\"3014\"]somatic nervous system[\/pb_glossary]. In the diagram\u00a0below, the autonomic system is shown on the left, and the somatic system on the right. Both systems of the PNS interact with the CNS and include sensory and motor neurons, but they use different\u00a0circuits\u00a0of nerves and ganglia.\r\n\r\n[caption id=\"attachment_3114\" align=\"aligncenter\" width=\"1075\"]![\"Autonomic](\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2023\/10\/Autonomic-and-Somatic-Nervous-System-2.png\")
Figure 8.6.4 The two major divisions of the PNS are the autonomic and sensory nervous systems.<\/em>[\/caption]\r\nSomatic Nervous System<\/h2>\r\nThe\u00a0[pb_glossary id=\"3014\"]somatic nervous system[\/pb_glossary]<\/strong>\u00a0primarily\u00a0senses\u00a0the external environment and controls voluntary activities about which decisions and commands come from the cerebral cortex of the brain. When you feel too warm, for example, you decide to turn on the air conditioner. As you walk across the room to the thermostat, you are using your somatic nervous system. In general, the somatic nervous system is responsible for all of your\u00a0conscious<\/em>\u00a0perceptions of the outside world, as well as all of the voluntary motor activities you perform in response. Whether it\u2019s playing a piano, driving a car, or playing basketball, you can thank your somatic nervous system for making it possible.\r\n\r\nSomatic sensory and motor information is transmitted through\u00a012 pairs of cranial nerves and 31 pairs of spinal nerves. Cranial nerves are in the head and neck and connect directly to the brain. Sensory components of cranial nerves\u00a0transmit information about\u00a0smells, tastes, light, sounds, and body position. Motor components of cranial nerves control\u00a0skeletal muscles\u00a0of the face, tongue, eyeballs, throat, head, and shoulders. Motor components of cranial nerves also control the salivary glands and swallowing. Four of the 12 cranial nerves participate in both sensory and motor functions as mixed nerves, having both sensory and motor neurons.\r\n\r\nSpinal nerves emanate from the spinal column between vertebrae. All of the spinal nerves are mixed nerves, containing both sensory and motor neurons. The areas of skin innervated by the 31 pairs of spinal nerves are shown in the figure\u00a0below. These include sensory nerves in the skin that sense pressure,\u00a0temperature, vibrations, and pain. Other sensory nerves are in the\u00a0muscles, and they sense stretching and tension. Spinal nerves also include motor nerves that stimulate\u00a0skeletal muscles\u00a0to contract, allowing for voluntary body movements.\r\n\r\n[caption id=\"attachment_3115\" align=\"aligncenter\" width=\"550\"]![\"Nerves\"](\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2023\/10\/Dermatoms.svg_-2.png\")
Figure 8.6.5 This drawing shows the areas of the skin innervated by sensory spinal nerves of the somatic nervous system. The left half of the figure shows the nerves in the front of the body, and the right half shows the nerves in the back of the body. The area that each spinal nerve innervates is shown in a different colour.<\/em>[\/caption]\r\nAutonomic Nervous System<\/h2>\r\nThe\u00a0[pb_glossary id=\"5899\"]autonomic nervous system[\/pb_glossary]<\/strong>\u00a0primarily\u00a0senses\u00a0the internal environment and controls involuntary activities. It is responsible for monitoring conditions in the internal environment and bringing about appropriate changes in them. In general, the\u00a0autonomic\u00a0nervous system is responsible for all the activities that go on inside your body\u00a0without<\/em>\u00a0your conscious awareness or voluntary participation.\r\n\r\nStructurally, the autonomic nervous system consists of sensory and motor nerves that run between the CNS (especially the hypothalamus in the brain), internal organs (such as the\u00a0heart, lungs, and digestive organs), and glands (such as the\u00a0pancreas\u00a0and sweat glands). [pb_glossary id=\"3030\"]Sensory neurons[\/pb_glossary] in the autonomic system detect internal body conditions and send messages to the brain. Motor nerves in the autonomic system affect appropriate responses by controlling contractions of smooth or cardiac muscle, or glandular tissue. For example, when sensory nerves of the autonomic system detect a rise in body\u00a0temperature, motor nerves signal smooth muscles in\u00a0blood vessels\u00a0near the body surface to undergo vasodilation, and the sweat glands in the skin to secrete more sweat to cool the body.\r\n\r\nThe autonomic nervous system, in turn, has three subdivisions: the [pb_glossary id=\"3015\"]sympathetic division[\/pb_glossary], [pb_glossary id=\"3016\"]parasympathetic division[\/pb_glossary], and [pb_glossary id=\"5987\"]enteric division[\/pb_glossary]. The first two subdivisions of the autonomic system are summarized in the figure\u00a0below. Both affect the same organs and glands, but they generally do so in opposite ways.\r\n\r\n \t- The\u00a0sympathetic division<\/strong>\u00a0controls the fight-or-flight response. Changes occur in organs and glands throughout the body that prepare the body to fight or flee in response to a perceived danger. For example, the\u00a0heart\u00a0rate speeds up, air passages in the lungs become wider, more\u00a0blood\u00a0flows to the\u00a0skeletal muscles, and the\u00a0digestive system temporarily shuts down.<\/li>\r\n \t
- The\u00a0parasympathetic division<\/strong>\u00a0returns the body to normal after the fight-or-flight response has occurred. For example, it slows down the\u00a0heart\u00a0rate, narrows air passages in the lungs, reduces\u00a0blood\u00a0flow to the skeletal muscles, and stimulates the\u00a0digestive system\u00a0to start working again. The parasympathetic division also maintains internal\u00a0homeostasis\u00a0of the body at other times.<\/li>\r\n \t
- The\u00a0enteric division<\/strong> is made up of nerve fibres that supply the organs of the digestive system. This division allows for the local control of many digestive functions.<\/li>\r\n<\/ul>\r\n[caption id=\"attachment_3116\" align=\"aligncenter\" width=\"597\"]
![\"The](\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2023\/10\/The_Autonomic_Nervous_System-2.jpg\")
Figure 8.6.6 This diagram summarizes the structures and functions controlled by the parasympathetic and sympathetic divisions of the autonomic nervous system.<\/em>[\/caption]\r\n\r\nDisorders of the Peripheral Nervous System<\/span>\r\n\r\nUnlike the CNS \u2014 which is protected by\u00a0[pb_glossary id=\"5913\"]bone[\/pb_glossary]s, [pb_glossary id=\"2929\"]meninges[\/pb_glossary], and [pb_glossary id=\"5939\"]cerebrospinal fluid[\/pb_glossary] \u2014 the PNS has no such protections. The PNS also has no blood-brain barrier to protect it from toxins and pathogens in the\u00a0blood. Therefore, the PNS is more subject to injury and disease than is the CNS. Causes of nerve injury include\u00a0diabetes<\/a>,\u00a0infectious diseases\u00a0(such as shingles<\/a>), and poisoning by toxins (such as heavy metals). PNS disorders often have symptoms\u00a0like\u00a0loss of feeling, tingling, burning sensations, or muscle weakness. If a traumatic injury results in a nerve being transected (cut all the way through), it may regenerate, but this is a very slow process and may take many months.\r\n\r\nTwo other diseases of the PNS are Guillain-Barre syndrome and Charcot-Marie-Tooth disease.\r\n\r\n \t- Guillain-Barre syndrome<\/a> is a rare disease in which the immune system attacks nerves of the PNS, leading to muscle weakness and even paralysis. The exact cause of Guillain-Barre syndrome is unknown, but it often occurs after a viral or bacterial infection. There is no known cure for the syndrome, but most people eventually make a full recovery. Recovery can be slow, however, lasting anywhere from several weeks to several years.<\/li>\r\n \t
- Charcot-Marie-Tooth disease<\/a> is a hereditary disorder of the nerves, and one of the most common inherited neurological disorders. It affects predominantly the nerves in the feet and legs,\u00a0and often\u00a0in the hands and arms, as well. The disease is characterized by loss of muscle tissue and sense of touch. It is presently incurable.<\/li>\r\n<\/ul>\r\n\r\n
Feature: My\u00a0Human Body<\/h1>\r\n<\/div>\r\nThe autonomic nervous system is considered to be involuntary because it doesn't require conscious input. However, it\u00a0is<\/em>\u00a0possible to exert some voluntary control over it. People who practice yoga or other so-called mind-body techniques, for example,\u00a0can\u00a0reduce their heart rate and certain other autonomic functions. Slowing down these otherwise involuntary responses is a good way to relieve stress and reduce the wear-and-tear that stress can place on the body. Such techniques may also be useful for controlling post-traumatic stress disorder and chronic pain. Three types of integrative practices for these purposes\u00a0are\u00a0breathing exercises, body-based tension modulation exercises, and mindfulness techniques.\r\n\r\nBreathing exercises can help control the rapid, shallow breathing that often occurs when you are anxious or under stress. These exercises can be learned quickly, and they provide immediate feelings of relief. Specific breathing exercises include paced breath, diaphragmatic breathing, and Breathe2Relax or Chill Zone on MindShift\u2122 CBT, which are downloadable breathing practice mobile applications, or \"Apps\". Try syncing your breathing with Eric Klassen's \"Triangle breathing, 1 minute\" video:\r\n\r\nhttps:\/\/www.youtube.com\/watch?v=u9Q8D6n-3qw\r\nTriangle breathing, 1 minute, Erin Klassen, 2015.<\/p>\r\nBody-based tension modulation exercises include yoga postures (also known as \u201casanas\u201d) and tension manipulation exercises. The latter include the Trauma\/Tension Release\u00a0Exercise\u00a0(TRE) and the Trauma Resiliency Model (TRM). Watch this video for a brief \u2014 but informative \u2014 introduction to the TRE program:\r\n\r\nhttps:\/\/www.youtube.com\/watch?v=67R974D8swM&feature=youtu.be\r\n
TRE\u00ae : Tension and Trauma Releasing Exercises, an Introduction with Jessica Schaffer, Jessica Schaffer Nervous System RESET, 2015.<\/p>\r\nMindfulness techniques have been shown to reduce symptoms of depression, as well as those of anxiety and stress. They have also been shown to be useful for pain management and performance enhancement. Specific mindfulness programs include Mindfulness Based Stress Reduction (MBSR) and Mindfulness Mind-Fitness Training (MMFT). You can learn more about MBSR by watching the video below.\r\n\r\nhttps:\/\/www.youtube.com\/watch?v=0TA7P-iCCcY&feature=youtu.be\r\n
Mindfulness-Based Stress Reduction (UMass Medical School, Center for Mindfulness), Palouse Mindfulness, 2017.<\/p>\r\n\r\n
\r\n8.6 Summary<\/span><\/h1>\r\n<\/header>\r\n\r\n\r\n \t- The [pb_glossary id=\"3009\"]peripheral nervous system[\/pb_glossary] (PNS) consists of all the nervous tissue that lies outside the\u00a0[pb_glossary id=\"5933\"]central nervous system[\/pb_glossary] (CNS). Its main function is to connect the CNS to the rest of the organism.<\/li>\r\n \t
- The PNS is made up of [pb_glossary id=\"3011\"]nerves[\/pb_glossary] and [pb_glossary id=\"6027\"]ganglia[\/pb_glossary]. Nerves are bundles of [pb_glossary id=\"5901\"]axons[\/pb_glossary], and ganglia are groups of [pb_glossary id=\"5931\"]cell bodies[\/pb_glossary]. Nerves are classified as sensory, motor, or a mix of the two.<\/li>\r\n \t
- The PNS is divided into the [pb_glossary id=\"3014\"]somatic[\/pb_glossary] and [pb_glossary id=\"5899\"]autonomic nervous systems[\/pb_glossary]. The somatic system controls [pb_glossary id=\"3004\"]voluntary[\/pb_glossary] activities, whereas the autonomic system controls [pb_glossary id=\"3005\"]involuntary[\/pb_glossary] activities.<\/li>\r\n \t
- The autonomic nervous system is further divided into [pb_glossary id=\"3015\"]sympathetic[\/pb_glossary], [pb_glossary id=\"3016\"]parasympathetic[\/pb_glossary], and [pb_glossary id=\"5987\"]enteric divisions[\/pb_glossary]. The sympathetic division controls [pb_glossary id=\"6013\"]fight-or-flight responses[\/pb_glossary]\u00a0during emergencies, the parasympathetic system controls routine body functions the rest of the time, and the enteric division provides local control over the [pb_glossary id=\"5969\"]digestive system[\/pb_glossary].<\/li>\r\n \t
- The PNS is not as well protected physically or chemically as the CNS, so it is more prone to injury and disease. PNS problems include injury from\u00a0diabetes, shingles, and heavy metal poisoning. Two disorders of the PNS are Guillain-Barre syndrome and Charcot-Marie-Tooth disease.<\/li>\r\n<\/ul>\r\n<\/div>\r\n<\/div>\r\n
\r\n8.6 Review Questions<\/span><\/h1>\r\n<\/header>\r\n\r\n\r\n \t- Describe the general structure of the peripheral nervous system. State its primary function.<\/li>\r\n \t
- What are ganglia?<\/li>\r\n \t
- Identify three types of nerves based on the direction in which they carry\u00a0nerve impulses.<\/li>\r\n \t
- Outline all of the divisions of the peripheral nervous system.<\/li>\r\n \t
- Compare and contrast the somatic and autonomic nervous systems.<\/li>\r\n \t
- When and how does the sympathetic division of the autonomic nervous system affect the body?<\/li>\r\n \t
- What is the function of the parasympathetic division of the autonomic nervous system?\u00a0Specifically, how does it affect the body?<\/li>\r\n \t
- Name and describe two peripheral nervous system disorders.<\/li>\r\n \t
- Give one example of how the CNS interacts with the PNS to control a function in the body.<\/li>\r\n \t
- For each of the following types of information, identify whether the neuron carrying it is sensory or motor, and whether it is most likely in the somatic or autonomic nervous system:\r\n
\r\n \t- Visual information<\/li>\r\n \t
- Blood pressure information<\/li>\r\n \t
- Information that causes muscle contraction in digestive organs after eating<\/li>\r\n \t
- Information that causes muscle contraction in skeletal muscles based on the person\u2019s decision to make a movement<\/li>\r\n<\/ol>\r\n<\/li>\r\n \t
- [h5p id=\"564\"]<\/li>\r\n<\/ol>\r\n<\/div>\r\n<\/div>\r\n
\r\n8.6 Explore More<\/span><\/h1>\r\n<\/header>\r\n\r\n\r\nhttps:\/\/www.youtube.com\/watch?v=ySIDMU2cy0Y&feature=emb_logo\r\nPhantom Limbs Explained, Plethrons, 2015.<\/p>\r\nhttps:\/\/www.youtube.com\/watch?time_continue=1&v=73yo5nJne6c&feature=emb_logo\r\n
Why Do Hot Peppers Cause Pain? Reactions, 2015.<\/p>\r\n\r\n<\/div>\r\n<\/div>\r\n
Attributions<\/h2>\r\nFigure 8.6.1<\/strong>\r\n\r\nKid\u2019s piant duet<\/a> by\u00a0PJMixer<\/a> on Flickr<\/a> is used under a CC BY-NC-ND 2.0<\/a>\u00a0(https:\/\/creativecommons.org\/licenses\/by-nc-nd\/2.0\/) license.\r\n\r\nFigure 8.6.2<\/strong>\r\n\r\nNervous_system_diagram<\/a> by \u00a4~Persian Poet Gal<\/span><\/span><\/a>\u00a0 on Wikimedia Commons is released into the public domain<\/a> (https:\/\/en.wikipedia.org\/wiki\/Public_domain).\r\n\r\n\r\nFigure 8.6.3<\/strong>\r\n\r\nAfferent_and_efferent_neurons_en.svg<\/a> by Helixitta<\/a> on Wikimedia Commons is used under a CC BY-SA 4.0 <\/a>\u00a0 (https:\/\/creativecommons.org\/licenses\/by-sa\/4.0) license.\r\n\r\nFigure 8.6.4<\/strong>\r\n\r\nAutonomic and Somatic Nervous System<\/a> by Christinelmiller<\/a> on Wikimedia Commons is used under a CC BY-SA 4.0<\/a> (https:\/\/creativecommons.org\/licenses\/by-sa\/4.0) license.\r\n\r\nFigure 8.6.5<\/strong>\r\n\r\nDermatoms.svg<\/a> by Ralf Stephan (mailto:ralf@ark.in-berlin.de) on Wikimedia Commons is released into the public domain<\/a> (https:\/\/en.wikipedia.org\/wiki\/Public_domain).\r\n\r\nFigure 8.6.6<\/strong>\r\n\r\nThe_Autonomic_Nervous_System<\/a> by Geo-Science-International<\/a> on Wikimedia Commons is used and adapted by Christine Miller under a\u00a0CC0 1.0<\/a> Universal\r\nPublic Domain Dedication license (https:\/\/creativecommons.org\/publicdomain\/zero\/1.0\/).\r\nReferences<\/h2>\r\n
Erin Klassen. (2015, December 15). Triangle breathing, 1 minute. YouTube. https:\/\/www.youtube.com\/watch?v=u9Q8D6n-3qw&feature=youtu.be<\/p>\r\n
Jessica Schaffer Nervous System RESET. (2015, January 15). TRE\u00ae : Tension and trauma releasing exercises, an Introduction with Jessica Schaffer. YouTube. https:\/\/www.youtube.com\/watch?v=67R974D8swM&feature=youtu.be<\/p>\r\n
Mayo Clinic Staff. (n.d.). Charcot-Marie-Tooth disease [online article]. MayoClinic.org. https:\/\/www.mayoclinic.org\/diseases-conditions\/charcot-marie-tooth-disease\/symptoms-causes\/syc-20350517<\/p>\r\n
Mayo Clinic Staff. (n.d.). Diabetes [online article]. MayoClinic.org. https:\/\/www.mayoclinic.org\/diseases-conditions\/diabetes\/symptoms-causes\/syc-20371444<\/p>\r\n
Mayo Clinic Staff. (n.d.). Guillain-Barre syndrome [online article]. MayoClinic.org. https:\/\/www.mayoclinic.org\/diseases-conditions\/guillain-barre-syndrome\/symptoms-causes\/syc-20362793<\/p>\r\n
Mayo Clinic Staff. (n.d.). Shingles [online article]. MayoClinic.org. https:\/\/www.mayoclinic.org\/diseases-conditions\/shingles\/symptoms-causes\/syc-20353054<\/p>\r\n
Mayo Clinic Staff. (n.d.). Stroke [online article]. MayoClinic.org. https:\/\/www.mayoclinic.org\/diseases-conditions\/stroke\/symptoms-causes\/syc-20350113<\/p>\r\n
Palouse Mindfulness. (2017, March 25).\u00a0 Mindfulness-based stress reduction (UMass Medical School, Center for Mindfulness), YouTube. https:\/\/www.youtube.com\/watch?v=0TA7P-iCCcY&feature=youtu.be<\/p>\r\n
Plethrons, (2015, March 23). Phantom limbs explained. YouTube. https:\/\/www.youtube.com\/watch?v=ySIDMU2cy0Y&feature=youtu.be<\/p>\r\n
Reactions. (2015, December 1). Why do hot peppers cause pain? YouTube. https:\/\/www.youtube.com\/watch?v=73yo5nJne6c&feature=youtu.be<\/p>\r\n \r\n\r\n \r\n\r\n ","rendered":"
<\/p>\n![\"\"](\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2019\/06\/Kids-piant-duet-by-PJMixer-on-Unsplash-2.jpg\")
Figure 8.6.1 A duet with the peripheral nervous system.\u00a0<\/em><\/figcaption><\/figure>\nOne Piano, Four Hands<\/h1>\n
Did you ever see two people play the same piano? How do they coordinate all the movements of their own fingers \u2014 let alone synchronize them with those of their partner? The peripheral nervous system plays an important part in this challenge.<\/p>\n
\nWhat Is the Peripheral Nervous System?<\/h1>\n<\/div>\n
The\u00a0peripheral nervous system<\/a> (PNS)<\/strong>\u00a0consists of all the nervous tissue that lies outside of the\u00a0central nervous system<\/a>\u00a0(CNS). The main function of the PNS is to connect the CNS to the rest of the organism. It serves as a\u00a0communication\u00a0relay, going back and forth between the CNS and\u00a0muscles, organs, and glands throughout the body.<\/p>\nFigure 8.6.2 The nerves of the peripheral nervous system are shown in blue in this diagram.<\/em><\/figcaption><\/figure>\n<\/div>\n\nTissues of the Peripheral Nervous System<\/h1>\n<\/div>\n
The PNS is mostly made up of cable-like bundles of axons called\u00a0nerves<\/a><\/strong>,\u00a0as well as\u00a0clusters of neuronal cell bodies called\u00a0ganglia<\/a><\/strong>\u00a0(singular,\u00a0ganglion<\/a><\/strong>). Nerves are generally classified\u00a0as sensory, motor, or mixed nerves\u00a0based on\u00a0the direction in which they carry\u00a0nerve impulses.<\/p>\n\n- Sensory nerves<\/strong>\u00a0transmit information from sensory receptors in the body to the CNS. Sensory nerves are also called afferent nerves. You can see an example in the figure\u00a0below.<\/li>\n
- Motor nerves<\/a><\/strong>\u00a0transmit information from the CNS to\u00a0muscles, organs, and glands. Motor nerves are also called efferent nerves. You can see one in the figure\u00a0below.<\/li>\n
- Mixed nerves<\/a><\/strong>\u00a0contain both sensory and motor neurons, so they can transmit information in both directions. They have both afferent and efferent functions.<\/li>\n<\/ul>\n
<\/p>\n
\nFigure 8.6.3 In this diagram, each nerve is depicted as a single neuron for simplicity. This afferent neuron sends nerve impulses from sensory receptors in the skin to the CNS. The efferent neuron is a motor neuron that sends nerve impulses from the CNS to a muscle. The cell body of the afferent neuron is located in a ganglion (not pictured), while the cell body of the motor neuron is located in the spinal cord.<\/em><\/figcaption><\/figure>\n<\/div>\n\nDivisions of the Peripheral Nervous System<\/h1>\n<\/div>\n
The PNS is divided into two major systems, called the autonomic nervous system<\/a> and the somatic nervous system<\/a>. In the diagram\u00a0below, the autonomic system is shown on the left, and the somatic system on the right. Both systems of the PNS interact with the CNS and include sensory and motor neurons, but they use different\u00a0circuits\u00a0of nerves and ganglia.<\/p>\nFigure 8.6.4 The two major divisions of the PNS are the autonomic and sensory nervous systems.<\/em><\/figcaption><\/figure>\nSomatic Nervous System<\/h2>\n
The\u00a0somatic nervous system<\/a><\/strong>\u00a0primarily\u00a0senses\u00a0the external environment and controls voluntary activities about which decisions and commands come from the cerebral cortex of the brain. When you feel too warm, for example, you decide to turn on the air conditioner. As you walk across the room to the thermostat, you are using your somatic nervous system. In general, the somatic nervous system is responsible for all of your\u00a0conscious<\/em>\u00a0perceptions of the outside world, as well as all of the voluntary motor activities you perform in response. Whether it\u2019s playing a piano, driving a car, or playing basketball, you can thank your somatic nervous system for making it possible.<\/p>\nSomatic sensory and motor information is transmitted through\u00a012 pairs of cranial nerves and 31 pairs of spinal nerves. Cranial nerves are in the head and neck and connect directly to the brain. Sensory components of cranial nerves\u00a0transmit information about\u00a0smells, tastes, light, sounds, and body position. Motor components of cranial nerves control\u00a0skeletal muscles\u00a0of the face, tongue, eyeballs, throat, head, and shoulders. Motor components of cranial nerves also control the salivary glands and swallowing. Four of the 12 cranial nerves participate in both sensory and motor functions as mixed nerves, having both sensory and motor neurons.<\/p>\n
Spinal nerves emanate from the spinal column between vertebrae. All of the spinal nerves are mixed nerves, containing both sensory and motor neurons. The areas of skin innervated by the 31 pairs of spinal nerves are shown in the figure\u00a0below. These include sensory nerves in the skin that sense pressure,\u00a0temperature, vibrations, and pain. Other sensory nerves are in the\u00a0muscles, and they sense stretching and tension. Spinal nerves also include motor nerves that stimulate\u00a0skeletal muscles\u00a0to contract, allowing for voluntary body movements.<\/p>\nFigure 8.6.5 This drawing shows the areas of the skin innervated by sensory spinal nerves of the somatic nervous system. The left half of the figure shows the nerves in the front of the body, and the right half shows the nerves in the back of the body. The area that each spinal nerve innervates is shown in a different colour.<\/em><\/figcaption><\/figure>\nAutonomic Nervous System<\/h2>\n
The\u00a0autonomic nervous system<\/a><\/strong>\u00a0primarily\u00a0senses\u00a0the internal environment and controls involuntary activities. It is responsible for monitoring conditions in the internal environment and bringing about appropriate changes in them. In general, the\u00a0autonomic\u00a0nervous system is responsible for all the activities that go on inside your body\u00a0without<\/em>\u00a0your conscious awareness or voluntary participation.<\/p>\nStructurally, the autonomic nervous system consists of sensory and motor nerves that run between the CNS (especially the hypothalamus in the brain), internal organs (such as the\u00a0heart, lungs, and digestive organs), and glands (such as the\u00a0pancreas\u00a0and sweat glands). Sensory neurons<\/a> in the autonomic system detect internal body conditions and send messages to the brain. Motor nerves in the autonomic system affect appropriate responses by controlling contractions of smooth or cardiac muscle, or glandular tissue. For example, when sensory nerves of the autonomic system detect a rise in body\u00a0temperature, motor nerves signal smooth muscles in\u00a0blood vessels\u00a0near the body surface to undergo vasodilation, and the sweat glands in the skin to secrete more sweat to cool the body.<\/p>\nThe autonomic nervous system, in turn, has three subdivisions: the sympathetic division<\/a>, parasympathetic division<\/a>, and enteric division<\/a>. The first two subdivisions of the autonomic system are summarized in the figure\u00a0below. Both affect the same organs and glands, but they generally do so in opposite ways.<\/p>\n\n- The\u00a0sympathetic division<\/strong>\u00a0controls the fight-or-flight response. Changes occur in organs and glands throughout the body that prepare the body to fight or flee in response to a perceived danger. For example, the\u00a0heart\u00a0rate speeds up, air passages in the lungs become wider, more\u00a0blood\u00a0flows to the\u00a0skeletal muscles, and the\u00a0digestive system temporarily shuts down.<\/li>\n
- The\u00a0parasympathetic division<\/strong>\u00a0returns the body to normal after the fight-or-flight response has occurred. For example, it slows down the\u00a0heart\u00a0rate, narrows air passages in the lungs, reduces\u00a0blood\u00a0flow to the skeletal muscles, and stimulates the\u00a0digestive system\u00a0to start working again. The parasympathetic division also maintains internal\u00a0homeostasis\u00a0of the body at other times.<\/li>\n
- The\u00a0enteric division<\/strong> is made up of nerve fibres that supply the organs of the digestive system. This division allows for the local control of many digestive functions.<\/li>\n<\/ul>\n
Figure 8.6.6 This diagram summarizes the structures and functions controlled by the parasympathetic and sympathetic divisions of the autonomic nervous system.<\/em><\/figcaption><\/figure>\nDisorders of the Peripheral Nervous System<\/span><\/p>\nUnlike the CNS \u2014 which is protected by\u00a0bone<\/a>s, meninges<\/a>, and cerebrospinal fluid<\/a> \u2014 the PNS has no such protections. The PNS also has no blood-brain barrier to protect it from toxins and pathogens in the\u00a0blood. Therefore, the PNS is more subject to injury and disease than is the CNS. Causes of nerve injury include\u00a0diabetes<\/a>,\u00a0infectious diseases\u00a0(such as shingles<\/a>), and poisoning by toxins (such as heavy metals). PNS disorders often have symptoms\u00a0like\u00a0loss of feeling, tingling, burning sensations, or muscle weakness. If a traumatic injury results in a nerve being transected (cut all the way through), it may regenerate, but this is a very slow process and may take many months.<\/p>\nTwo other diseases of the PNS are Guillain-Barre syndrome and Charcot-Marie-Tooth disease.<\/p>\n
\n- Guillain-Barre syndrome<\/a> is a rare disease in which the immune system attacks nerves of the PNS, leading to muscle weakness and even paralysis. The exact cause of Guillain-Barre syndrome is unknown, but it often occurs after a viral or bacterial infection. There is no known cure for the syndrome, but most people eventually make a full recovery. Recovery can be slow, however, lasting anywhere from several weeks to several years.<\/li>\n
- Charcot-Marie-Tooth disease<\/a> is a hereditary disorder of the nerves, and one of the most common inherited neurological disorders. It affects predominantly the nerves in the feet and legs,\u00a0and often\u00a0in the hands and arms, as well. The disease is characterized by loss of muscle tissue and sense of touch. It is presently incurable.<\/li>\n<\/ul>\n\n
Feature: My\u00a0Human Body<\/h1>\n<\/div>\n
The autonomic nervous system is considered to be involuntary because it doesn’t require conscious input. However, it\u00a0is<\/em>\u00a0possible to exert some voluntary control over it. People who practice yoga or other so-called mind-body techniques, for example,\u00a0can\u00a0reduce their heart rate and certain other autonomic functions. Slowing down these otherwise involuntary responses is a good way to relieve stress and reduce the wear-and-tear that stress can place on the body. Such techniques may also be useful for controlling post-traumatic stress disorder and chronic pain. Three types of integrative practices for these purposes\u00a0are\u00a0breathing exercises, body-based tension modulation exercises, and mindfulness techniques.<\/p>\nBreathing exercises can help control the rapid, shallow breathing that often occurs when you are anxious or under stress. These exercises can be learned quickly, and they provide immediate feelings of relief. Specific breathing exercises include paced breath, diaphragmatic breathing, and Breathe2Relax or Chill Zone on MindShift\u2122 CBT, which are downloadable breathing practice mobile applications, or “Apps”. Try syncing your breathing with Eric Klassen’s “Triangle breathing, 1 minute” video:<\/p>\n
https:\/\/www.youtube.com\/watch?v=u9Q8D6n-3qw<\/p>\n
Triangle breathing, 1 minute, Erin Klassen, 2015.<\/p>\n
Body-based tension modulation exercises include yoga postures (also known as \u201casanas\u201d) and tension manipulation exercises. The latter include the Trauma\/Tension Release\u00a0Exercise\u00a0(TRE) and the Trauma Resiliency Model (TRM). Watch this video for a brief \u2014 but informative \u2014 introduction to the TRE program:<\/p>\n
https:\/\/www.youtube.com\/watch?v=67R974D8swM&feature=youtu.be<\/p>\n
TRE\u00ae : Tension and Trauma Releasing Exercises, an Introduction with Jessica Schaffer, Jessica Schaffer Nervous System RESET, 2015.<\/p>\n
Mindfulness techniques have been shown to reduce symptoms of depression, as well as those of anxiety and stress. They have also been shown to be useful for pain management and performance enhancement. Specific mindfulness programs include Mindfulness Based Stress Reduction (MBSR) and Mindfulness Mind-Fitness Training (MMFT). You can learn more about MBSR by watching the video below.<\/p>\n
Tissues of the Peripheral Nervous System<\/h1>\r\n<\/div>\r\nThe PNS is mostly made up of cable-like bundles of axons called\u00a0[pb_glossary id=\"3011\"]nerves[\/pb_glossary]<\/strong>,\u00a0as well as\u00a0clusters of neuronal cell bodies called\u00a0[pb_glossary id=\"6027\"]ganglia[\/pb_glossary]<\/strong>\u00a0(singular,\u00a0[pb_glossary id=\"6029\"]ganglion[\/pb_glossary]<\/strong>). Nerves are generally classified\u00a0as sensory, motor, or mixed nerves\u00a0based on\u00a0the direction in which they carry\u00a0nerve impulses.\r\n\r\n \t- [pb_glossary id=\"3110\"]Sensory nerves[\/pb_glossary]<\/strong>\u00a0transmit information from sensory receptors in the body to the CNS. Sensory nerves are also called afferent nerves. You can see an example in the figure\u00a0below.<\/li>\r\n \t
- [pb_glossary id=\"3111\"]Motor nerves[\/pb_glossary]<\/strong>\u00a0transmit information from the CNS to\u00a0muscles, organs, and glands. Motor nerves are also called efferent nerves. You can see one in the figure\u00a0below.<\/li>\r\n \t
- [pb_glossary id=\"3112\"]Mixed nerves[\/pb_glossary]<\/strong>\u00a0contain both sensory and motor neurons, so they can transmit information in both directions. They have both afferent and efferent functions.<\/li>\r\n<\/ul>\r\n \r\n\r\n\r\n[caption id=\"attachment_3113\" align=\"aligncenter\" width=\"868\"] Figure 8.6.3 In this diagram, each nerve is depicted as a single neuron for simplicity. This afferent neuron sends nerve impulses from sensory receptors in the skin to the CNS. The efferent neuron is a motor neuron that sends nerve impulses from the CNS to a muscle. The cell body of the afferent neuron is located in a ganglion (not pictured), while the cell body of the motor neuron is located in the spinal cord.<\/em>[\/caption]\r\n\r\n<\/div>\r\n\r\n
Divisions of the Peripheral Nervous System<\/h1>\r\n<\/div>\r\nThe PNS is divided into two major systems, called the [pb_glossary id=\"5899\"]autonomic nervous system[\/pb_glossary] and the [pb_glossary id=\"3014\"]somatic nervous system[\/pb_glossary]. In the diagram\u00a0below, the autonomic system is shown on the left, and the somatic system on the right. Both systems of the PNS interact with the CNS and include sensory and motor neurons, but they use different\u00a0circuits\u00a0of nerves and ganglia.\r\n\r\n[caption id=\"attachment_3114\" align=\"aligncenter\" width=\"1075\"] Figure 8.6.4 The two major divisions of the PNS are the autonomic and sensory nervous systems.<\/em>[\/caption]\r\nSomatic Nervous System<\/h2>\r\nThe\u00a0[pb_glossary id=\"3014\"]somatic nervous system[\/pb_glossary]<\/strong>\u00a0primarily\u00a0senses\u00a0the external environment and controls voluntary activities about which decisions and commands come from the cerebral cortex of the brain. When you feel too warm, for example, you decide to turn on the air conditioner. As you walk across the room to the thermostat, you are using your somatic nervous system. In general, the somatic nervous system is responsible for all of your\u00a0conscious<\/em>\u00a0perceptions of the outside world, as well as all of the voluntary motor activities you perform in response. Whether it\u2019s playing a piano, driving a car, or playing basketball, you can thank your somatic nervous system for making it possible.\r\n\r\nSomatic sensory and motor information is transmitted through\u00a012 pairs of cranial nerves and 31 pairs of spinal nerves. Cranial nerves are in the head and neck and connect directly to the brain. Sensory components of cranial nerves\u00a0transmit information about\u00a0smells, tastes, light, sounds, and body position. Motor components of cranial nerves control\u00a0skeletal muscles\u00a0of the face, tongue, eyeballs, throat, head, and shoulders. Motor components of cranial nerves also control the salivary glands and swallowing. Four of the 12 cranial nerves participate in both sensory and motor functions as mixed nerves, having both sensory and motor neurons.\r\n\r\nSpinal nerves emanate from the spinal column between vertebrae. All of the spinal nerves are mixed nerves, containing both sensory and motor neurons. The areas of skin innervated by the 31 pairs of spinal nerves are shown in the figure\u00a0below. These include sensory nerves in the skin that sense pressure,\u00a0temperature, vibrations, and pain. Other sensory nerves are in the\u00a0muscles, and they sense stretching and tension. Spinal nerves also include motor nerves that stimulate\u00a0skeletal muscles\u00a0to contract, allowing for voluntary body movements.\r\n\r\n[caption id=\"attachment_3115\" align=\"aligncenter\" width=\"550\"] Figure 8.6.5 This drawing shows the areas of the skin innervated by sensory spinal nerves of the somatic nervous system. The left half of the figure shows the nerves in the front of the body, and the right half shows the nerves in the back of the body. The area that each spinal nerve innervates is shown in a different colour.<\/em>[\/caption]\r\nAutonomic Nervous System<\/h2>\r\nThe\u00a0[pb_glossary id=\"5899\"]autonomic nervous system[\/pb_glossary]<\/strong>\u00a0primarily\u00a0senses\u00a0the internal environment and controls involuntary activities. It is responsible for monitoring conditions in the internal environment and bringing about appropriate changes in them. In general, the\u00a0autonomic\u00a0nervous system is responsible for all the activities that go on inside your body\u00a0without<\/em>\u00a0your conscious awareness or voluntary participation.\r\n\r\nStructurally, the autonomic nervous system consists of sensory and motor nerves that run between the CNS (especially the hypothalamus in the brain), internal organs (such as the\u00a0heart, lungs, and digestive organs), and glands (such as the\u00a0pancreas\u00a0and sweat glands). [pb_glossary id=\"3030\"]Sensory neurons[\/pb_glossary] in the autonomic system detect internal body conditions and send messages to the brain. Motor nerves in the autonomic system affect appropriate responses by controlling contractions of smooth or cardiac muscle, or glandular tissue. For example, when sensory nerves of the autonomic system detect a rise in body\u00a0temperature, motor nerves signal smooth muscles in\u00a0blood vessels\u00a0near the body surface to undergo vasodilation, and the sweat glands in the skin to secrete more sweat to cool the body.\r\n\r\nThe autonomic nervous system, in turn, has three subdivisions: the [pb_glossary id=\"3015\"]sympathetic division[\/pb_glossary], [pb_glossary id=\"3016\"]parasympathetic division[\/pb_glossary], and [pb_glossary id=\"5987\"]enteric division[\/pb_glossary]. The first two subdivisions of the autonomic system are summarized in the figure\u00a0below. Both affect the same organs and glands, but they generally do so in opposite ways.\r\n\r\n \t- The\u00a0sympathetic division<\/strong>\u00a0controls the fight-or-flight response. Changes occur in organs and glands throughout the body that prepare the body to fight or flee in response to a perceived danger. For example, the\u00a0heart\u00a0rate speeds up, air passages in the lungs become wider, more\u00a0blood\u00a0flows to the\u00a0skeletal muscles, and the\u00a0digestive system temporarily shuts down.<\/li>\r\n \t
- The\u00a0parasympathetic division<\/strong>\u00a0returns the body to normal after the fight-or-flight response has occurred. For example, it slows down the\u00a0heart\u00a0rate, narrows air passages in the lungs, reduces\u00a0blood\u00a0flow to the skeletal muscles, and stimulates the\u00a0digestive system\u00a0to start working again. The parasympathetic division also maintains internal\u00a0homeostasis\u00a0of the body at other times.<\/li>\r\n \t
- The\u00a0enteric division<\/strong> is made up of nerve fibres that supply the organs of the digestive system. This division allows for the local control of many digestive functions.<\/li>\r\n<\/ul>\r\n[caption id=\"attachment_3116\" align=\"aligncenter\" width=\"597\"] Figure 8.6.6 This diagram summarizes the structures and functions controlled by the parasympathetic and sympathetic divisions of the autonomic nervous system.<\/em>[\/caption]\r\n\r\nDisorders of the Peripheral Nervous System<\/span>\r\n\r\nUnlike the CNS \u2014 which is protected by\u00a0[pb_glossary id=\"5913\"]bone[\/pb_glossary]s, [pb_glossary id=\"2929\"]meninges[\/pb_glossary], and [pb_glossary id=\"5939\"]cerebrospinal fluid[\/pb_glossary] \u2014 the PNS has no such protections. The PNS also has no blood-brain barrier to protect it from toxins and pathogens in the\u00a0blood. Therefore, the PNS is more subject to injury and disease than is the CNS. Causes of nerve injury include\u00a0diabetes<\/a>,\u00a0infectious diseases\u00a0(such as shingles<\/a>), and poisoning by toxins (such as heavy metals). PNS disorders often have symptoms\u00a0like\u00a0loss of feeling, tingling, burning sensations, or muscle weakness. If a traumatic injury results in a nerve being transected (cut all the way through), it may regenerate, but this is a very slow process and may take many months.\r\n\r\nTwo other diseases of the PNS are Guillain-Barre syndrome and Charcot-Marie-Tooth disease.\r\n
\r\n \t- Guillain-Barre syndrome<\/a> is a rare disease in which the immune system attacks nerves of the PNS, leading to muscle weakness and even paralysis. The exact cause of Guillain-Barre syndrome is unknown, but it often occurs after a viral or bacterial infection. There is no known cure for the syndrome, but most people eventually make a full recovery. Recovery can be slow, however, lasting anywhere from several weeks to several years.<\/li>\r\n \t
- Charcot-Marie-Tooth disease<\/a> is a hereditary disorder of the nerves, and one of the most common inherited neurological disorders. It affects predominantly the nerves in the feet and legs,\u00a0and often\u00a0in the hands and arms, as well. The disease is characterized by loss of muscle tissue and sense of touch. It is presently incurable.<\/li>\r\n<\/ul>\r\n\r\n
Feature: My\u00a0Human Body<\/h1>\r\n<\/div>\r\nThe autonomic nervous system is considered to be involuntary because it doesn't require conscious input. However, it\u00a0is<\/em>\u00a0possible to exert some voluntary control over it. People who practice yoga or other so-called mind-body techniques, for example,\u00a0can\u00a0reduce their heart rate and certain other autonomic functions. Slowing down these otherwise involuntary responses is a good way to relieve stress and reduce the wear-and-tear that stress can place on the body. Such techniques may also be useful for controlling post-traumatic stress disorder and chronic pain. Three types of integrative practices for these purposes\u00a0are\u00a0breathing exercises, body-based tension modulation exercises, and mindfulness techniques.\r\n\r\nBreathing exercises can help control the rapid, shallow breathing that often occurs when you are anxious or under stress. These exercises can be learned quickly, and they provide immediate feelings of relief. Specific breathing exercises include paced breath, diaphragmatic breathing, and Breathe2Relax or Chill Zone on MindShift\u2122 CBT, which are downloadable breathing practice mobile applications, or \"Apps\". Try syncing your breathing with Eric Klassen's \"Triangle breathing, 1 minute\" video:\r\n\r\nhttps:\/\/www.youtube.com\/watch?v=u9Q8D6n-3qw\r\nTriangle breathing, 1 minute, Erin Klassen, 2015.<\/p>\r\nBody-based tension modulation exercises include yoga postures (also known as \u201casanas\u201d) and tension manipulation exercises. The latter include the Trauma\/Tension Release\u00a0Exercise\u00a0(TRE) and the Trauma Resiliency Model (TRM). Watch this video for a brief \u2014 but informative \u2014 introduction to the TRE program:\r\n\r\nhttps:\/\/www.youtube.com\/watch?v=67R974D8swM&feature=youtu.be\r\n
TRE\u00ae : Tension and Trauma Releasing Exercises, an Introduction with Jessica Schaffer, Jessica Schaffer Nervous System RESET, 2015.<\/p>\r\nMindfulness techniques have been shown to reduce symptoms of depression, as well as those of anxiety and stress. They have also been shown to be useful for pain management and performance enhancement. Specific mindfulness programs include Mindfulness Based Stress Reduction (MBSR) and Mindfulness Mind-Fitness Training (MMFT). You can learn more about MBSR by watching the video below.\r\n\r\nhttps:\/\/www.youtube.com\/watch?v=0TA7P-iCCcY&feature=youtu.be\r\n
Mindfulness-Based Stress Reduction (UMass Medical School, Center for Mindfulness), Palouse Mindfulness, 2017.<\/p>\r\n\r\n
\r\n8.6 Summary<\/span><\/h1>\r\n<\/header>\r\n\r\n\r\n \t- The [pb_glossary id=\"3009\"]peripheral nervous system[\/pb_glossary] (PNS) consists of all the nervous tissue that lies outside the\u00a0[pb_glossary id=\"5933\"]central nervous system[\/pb_glossary] (CNS). Its main function is to connect the CNS to the rest of the organism.<\/li>\r\n \t
- The PNS is made up of [pb_glossary id=\"3011\"]nerves[\/pb_glossary] and [pb_glossary id=\"6027\"]ganglia[\/pb_glossary]. Nerves are bundles of [pb_glossary id=\"5901\"]axons[\/pb_glossary], and ganglia are groups of [pb_glossary id=\"5931\"]cell bodies[\/pb_glossary]. Nerves are classified as sensory, motor, or a mix of the two.<\/li>\r\n \t
- The PNS is divided into the [pb_glossary id=\"3014\"]somatic[\/pb_glossary] and [pb_glossary id=\"5899\"]autonomic nervous systems[\/pb_glossary]. The somatic system controls [pb_glossary id=\"3004\"]voluntary[\/pb_glossary] activities, whereas the autonomic system controls [pb_glossary id=\"3005\"]involuntary[\/pb_glossary] activities.<\/li>\r\n \t
- The autonomic nervous system is further divided into [pb_glossary id=\"3015\"]sympathetic[\/pb_glossary], [pb_glossary id=\"3016\"]parasympathetic[\/pb_glossary], and [pb_glossary id=\"5987\"]enteric divisions[\/pb_glossary]. The sympathetic division controls [pb_glossary id=\"6013\"]fight-or-flight responses[\/pb_glossary]\u00a0during emergencies, the parasympathetic system controls routine body functions the rest of the time, and the enteric division provides local control over the [pb_glossary id=\"5969\"]digestive system[\/pb_glossary].<\/li>\r\n \t
- The PNS is not as well protected physically or chemically as the CNS, so it is more prone to injury and disease. PNS problems include injury from\u00a0diabetes, shingles, and heavy metal poisoning. Two disorders of the PNS are Guillain-Barre syndrome and Charcot-Marie-Tooth disease.<\/li>\r\n<\/ul>\r\n<\/div>\r\n<\/div>\r\n
\r\n8.6 Review Questions<\/span><\/h1>\r\n<\/header>\r\n\r\n\r\n \t- Describe the general structure of the peripheral nervous system. State its primary function.<\/li>\r\n \t
- What are ganglia?<\/li>\r\n \t
- Identify three types of nerves based on the direction in which they carry\u00a0nerve impulses.<\/li>\r\n \t
- Outline all of the divisions of the peripheral nervous system.<\/li>\r\n \t
- Compare and contrast the somatic and autonomic nervous systems.<\/li>\r\n \t
- When and how does the sympathetic division of the autonomic nervous system affect the body?<\/li>\r\n \t
- What is the function of the parasympathetic division of the autonomic nervous system?\u00a0Specifically, how does it affect the body?<\/li>\r\n \t
- Name and describe two peripheral nervous system disorders.<\/li>\r\n \t
- Give one example of how the CNS interacts with the PNS to control a function in the body.<\/li>\r\n \t
- For each of the following types of information, identify whether the neuron carrying it is sensory or motor, and whether it is most likely in the somatic or autonomic nervous system:\r\n
\r\n \t- Visual information<\/li>\r\n \t
- Blood pressure information<\/li>\r\n \t
- Information that causes muscle contraction in digestive organs after eating<\/li>\r\n \t
- Information that causes muscle contraction in skeletal muscles based on the person\u2019s decision to make a movement<\/li>\r\n<\/ol>\r\n<\/li>\r\n \t
- [h5p id=\"564\"]<\/li>\r\n<\/ol>\r\n<\/div>\r\n<\/div>\r\n
\r\n8.6 Explore More<\/span><\/h1>\r\n<\/header>\r\n\r\n\r\nhttps:\/\/www.youtube.com\/watch?v=ySIDMU2cy0Y&feature=emb_logo\r\nPhantom Limbs Explained, Plethrons, 2015.<\/p>\r\nhttps:\/\/www.youtube.com\/watch?time_continue=1&v=73yo5nJne6c&feature=emb_logo\r\n
Why Do Hot Peppers Cause Pain? Reactions, 2015.<\/p>\r\n\r\n<\/div>\r\n<\/div>\r\n
Attributions<\/h2>\r\nFigure 8.6.1<\/strong>\r\n\r\nKid\u2019s piant duet<\/a> by\u00a0PJMixer<\/a> on Flickr<\/a> is used under a CC BY-NC-ND 2.0<\/a>\u00a0(https:\/\/creativecommons.org\/licenses\/by-nc-nd\/2.0\/) license.\r\n\r\nFigure 8.6.2<\/strong>\r\n\r\nNervous_system_diagram<\/a> by \u00a4~Persian Poet Gal<\/span><\/span><\/a>\u00a0 on Wikimedia Commons is released into the public domain<\/a> (https:\/\/en.wikipedia.org\/wiki\/Public_domain).\r\n\r\n\r\nFigure 8.6.3<\/strong>\r\n\r\nAfferent_and_efferent_neurons_en.svg<\/a> by Helixitta<\/a> on Wikimedia Commons is used under a CC BY-SA 4.0 <\/a>\u00a0 (https:\/\/creativecommons.org\/licenses\/by-sa\/4.0) license.\r\n\r\nFigure 8.6.4<\/strong>\r\n\r\nAutonomic and Somatic Nervous System<\/a> by Christinelmiller<\/a> on Wikimedia Commons is used under a CC BY-SA 4.0<\/a> (https:\/\/creativecommons.org\/licenses\/by-sa\/4.0) license.\r\n\r\nFigure 8.6.5<\/strong>\r\n\r\nDermatoms.svg<\/a> by Ralf Stephan (mailto:ralf@ark.in-berlin.de) on Wikimedia Commons is released into the public domain<\/a> (https:\/\/en.wikipedia.org\/wiki\/Public_domain).\r\n\r\nFigure 8.6.6<\/strong>\r\n\r\nThe_Autonomic_Nervous_System<\/a> by Geo-Science-International<\/a> on Wikimedia Commons is used and adapted by Christine Miller under a\u00a0CC0 1.0<\/a> Universal\r\nPublic Domain Dedication license (https:\/\/creativecommons.org\/publicdomain\/zero\/1.0\/).\r\nReferences<\/h2>\r\n
Erin Klassen. (2015, December 15). Triangle breathing, 1 minute. YouTube. https:\/\/www.youtube.com\/watch?v=u9Q8D6n-3qw&feature=youtu.be<\/p>\r\n
Jessica Schaffer Nervous System RESET. (2015, January 15). TRE\u00ae : Tension and trauma releasing exercises, an Introduction with Jessica Schaffer. YouTube. https:\/\/www.youtube.com\/watch?v=67R974D8swM&feature=youtu.be<\/p>\r\n
Mayo Clinic Staff. (n.d.). Charcot-Marie-Tooth disease [online article]. MayoClinic.org. https:\/\/www.mayoclinic.org\/diseases-conditions\/charcot-marie-tooth-disease\/symptoms-causes\/syc-20350517<\/p>\r\n
Mayo Clinic Staff. (n.d.). Diabetes [online article]. MayoClinic.org. https:\/\/www.mayoclinic.org\/diseases-conditions\/diabetes\/symptoms-causes\/syc-20371444<\/p>\r\n
Mayo Clinic Staff. (n.d.). Guillain-Barre syndrome [online article]. MayoClinic.org. https:\/\/www.mayoclinic.org\/diseases-conditions\/guillain-barre-syndrome\/symptoms-causes\/syc-20362793<\/p>\r\n
Mayo Clinic Staff. (n.d.). Shingles [online article]. MayoClinic.org. https:\/\/www.mayoclinic.org\/diseases-conditions\/shingles\/symptoms-causes\/syc-20353054<\/p>\r\n
Mayo Clinic Staff. (n.d.). Stroke [online article]. MayoClinic.org. https:\/\/www.mayoclinic.org\/diseases-conditions\/stroke\/symptoms-causes\/syc-20350113<\/p>\r\n
Palouse Mindfulness. (2017, March 25).\u00a0 Mindfulness-based stress reduction (UMass Medical School, Center for Mindfulness), YouTube. https:\/\/www.youtube.com\/watch?v=0TA7P-iCCcY&feature=youtu.be<\/p>\r\n
Plethrons, (2015, March 23). Phantom limbs explained. YouTube. https:\/\/www.youtube.com\/watch?v=ySIDMU2cy0Y&feature=youtu.be<\/p>\r\n
Reactions. (2015, December 1). Why do hot peppers cause pain? YouTube. https:\/\/www.youtube.com\/watch?v=73yo5nJne6c&feature=youtu.be<\/p>\r\n \r\n\r\n \r\n\r\n ","rendered":"
<\/p>\nFigure 8.6.1 A duet with the peripheral nervous system.\u00a0<\/em><\/figcaption><\/figure>\nOne Piano, Four Hands<\/h1>\n
Did you ever see two people play the same piano? How do they coordinate all the movements of their own fingers \u2014 let alone synchronize them with those of their partner? The peripheral nervous system plays an important part in this challenge.<\/p>\n
\nWhat Is the Peripheral Nervous System?<\/h1>\n<\/div>\n
The\u00a0peripheral nervous system<\/a> (PNS)<\/strong>\u00a0consists of all the nervous tissue that lies outside of the\u00a0central nervous system<\/a>\u00a0(CNS). The main function of the PNS is to connect the CNS to the rest of the organism. It serves as a\u00a0communication\u00a0relay, going back and forth between the CNS and\u00a0muscles, organs, and glands throughout the body.<\/p>\nFigure 8.6.2 The nerves of the peripheral nervous system are shown in blue in this diagram.<\/em><\/figcaption><\/figure>\n<\/div>\n\nTissues of the Peripheral Nervous System<\/h1>\n<\/div>\n
The PNS is mostly made up of cable-like bundles of axons called\u00a0nerves<\/a><\/strong>,\u00a0as well as\u00a0clusters of neuronal cell bodies called\u00a0ganglia<\/a><\/strong>\u00a0(singular,\u00a0ganglion<\/a><\/strong>). Nerves are generally classified\u00a0as sensory, motor, or mixed nerves\u00a0based on\u00a0the direction in which they carry\u00a0nerve impulses.<\/p>\n\n- Sensory nerves<\/strong>\u00a0transmit information from sensory receptors in the body to the CNS. Sensory nerves are also called afferent nerves. You can see an example in the figure\u00a0below.<\/li>\n
- Motor nerves<\/a><\/strong>\u00a0transmit information from the CNS to\u00a0muscles, organs, and glands. Motor nerves are also called efferent nerves. You can see one in the figure\u00a0below.<\/li>\n
- Mixed nerves<\/a><\/strong>\u00a0contain both sensory and motor neurons, so they can transmit information in both directions. They have both afferent and efferent functions.<\/li>\n<\/ul>\n
<\/p>\n
\nFigure 8.6.3 In this diagram, each nerve is depicted as a single neuron for simplicity. This afferent neuron sends nerve impulses from sensory receptors in the skin to the CNS. The efferent neuron is a motor neuron that sends nerve impulses from the CNS to a muscle. The cell body of the afferent neuron is located in a ganglion (not pictured), while the cell body of the motor neuron is located in the spinal cord.<\/em><\/figcaption><\/figure>\n<\/div>\n\nDivisions of the Peripheral Nervous System<\/h1>\n<\/div>\n
The PNS is divided into two major systems, called the autonomic nervous system<\/a> and the somatic nervous system<\/a>. In the diagram\u00a0below, the autonomic system is shown on the left, and the somatic system on the right. Both systems of the PNS interact with the CNS and include sensory and motor neurons, but they use different\u00a0circuits\u00a0of nerves and ganglia.<\/p>\nFigure 8.6.4 The two major divisions of the PNS are the autonomic and sensory nervous systems.<\/em><\/figcaption><\/figure>\nSomatic Nervous System<\/h2>\n
The\u00a0somatic nervous system<\/a><\/strong>\u00a0primarily\u00a0senses\u00a0the external environment and controls voluntary activities about which decisions and commands come from the cerebral cortex of the brain. When you feel too warm, for example, you decide to turn on the air conditioner. As you walk across the room to the thermostat, you are using your somatic nervous system. In general, the somatic nervous system is responsible for all of your\u00a0conscious<\/em>\u00a0perceptions of the outside world, as well as all of the voluntary motor activities you perform in response. Whether it\u2019s playing a piano, driving a car, or playing basketball, you can thank your somatic nervous system for making it possible.<\/p>\nSomatic sensory and motor information is transmitted through\u00a012 pairs of cranial nerves and 31 pairs of spinal nerves. Cranial nerves are in the head and neck and connect directly to the brain. Sensory components of cranial nerves\u00a0transmit information about\u00a0smells, tastes, light, sounds, and body position. Motor components of cranial nerves control\u00a0skeletal muscles\u00a0of the face, tongue, eyeballs, throat, head, and shoulders. Motor components of cranial nerves also control the salivary glands and swallowing. Four of the 12 cranial nerves participate in both sensory and motor functions as mixed nerves, having both sensory and motor neurons.<\/p>\n
Spinal nerves emanate from the spinal column between vertebrae. All of the spinal nerves are mixed nerves, containing both sensory and motor neurons. The areas of skin innervated by the 31 pairs of spinal nerves are shown in the figure\u00a0below. These include sensory nerves in the skin that sense pressure,\u00a0temperature, vibrations, and pain. Other sensory nerves are in the\u00a0muscles, and they sense stretching and tension. Spinal nerves also include motor nerves that stimulate\u00a0skeletal muscles\u00a0to contract, allowing for voluntary body movements.<\/p>\nFigure 8.6.5 This drawing shows the areas of the skin innervated by sensory spinal nerves of the somatic nervous system. The left half of the figure shows the nerves in the front of the body, and the right half shows the nerves in the back of the body. The area that each spinal nerve innervates is shown in a different colour.<\/em><\/figcaption><\/figure>\nAutonomic Nervous System<\/h2>\n
The\u00a0autonomic nervous system<\/a><\/strong>\u00a0primarily\u00a0senses\u00a0the internal environment and controls involuntary activities. It is responsible for monitoring conditions in the internal environment and bringing about appropriate changes in them. In general, the\u00a0autonomic\u00a0nervous system is responsible for all the activities that go on inside your body\u00a0without<\/em>\u00a0your conscious awareness or voluntary participation.<\/p>\nStructurally, the autonomic nervous system consists of sensory and motor nerves that run between the CNS (especially the hypothalamus in the brain), internal organs (such as the\u00a0heart, lungs, and digestive organs), and glands (such as the\u00a0pancreas\u00a0and sweat glands). Sensory neurons<\/a> in the autonomic system detect internal body conditions and send messages to the brain. Motor nerves in the autonomic system affect appropriate responses by controlling contractions of smooth or cardiac muscle, or glandular tissue. For example, when sensory nerves of the autonomic system detect a rise in body\u00a0temperature, motor nerves signal smooth muscles in\u00a0blood vessels\u00a0near the body surface to undergo vasodilation, and the sweat glands in the skin to secrete more sweat to cool the body.<\/p>\nThe autonomic nervous system, in turn, has three subdivisions: the sympathetic division<\/a>, parasympathetic division<\/a>, and enteric division<\/a>. The first two subdivisions of the autonomic system are summarized in the figure\u00a0below. Both affect the same organs and glands, but they generally do so in opposite ways.<\/p>\n\n- The\u00a0sympathetic division<\/strong>\u00a0controls the fight-or-flight response. Changes occur in organs and glands throughout the body that prepare the body to fight or flee in response to a perceived danger. For example, the\u00a0heart\u00a0rate speeds up, air passages in the lungs become wider, more\u00a0blood\u00a0flows to the\u00a0skeletal muscles, and the\u00a0digestive system temporarily shuts down.<\/li>\n
- The\u00a0parasympathetic division<\/strong>\u00a0returns the body to normal after the fight-or-flight response has occurred. For example, it slows down the\u00a0heart\u00a0rate, narrows air passages in the lungs, reduces\u00a0blood\u00a0flow to the skeletal muscles, and stimulates the\u00a0digestive system\u00a0to start working again. The parasympathetic division also maintains internal\u00a0homeostasis\u00a0of the body at other times.<\/li>\n
- The\u00a0enteric division<\/strong> is made up of nerve fibres that supply the organs of the digestive system. This division allows for the local control of many digestive functions.<\/li>\n<\/ul>\n
Figure 8.6.6 This diagram summarizes the structures and functions controlled by the parasympathetic and sympathetic divisions of the autonomic nervous system.<\/em><\/figcaption><\/figure>\nDisorders of the Peripheral Nervous System<\/span><\/p>\nUnlike the CNS \u2014 which is protected by\u00a0bone<\/a>s, meninges<\/a>, and cerebrospinal fluid<\/a> \u2014 the PNS has no such protections. The PNS also has no blood-brain barrier to protect it from toxins and pathogens in the\u00a0blood. Therefore, the PNS is more subject to injury and disease than is the CNS. Causes of nerve injury include\u00a0diabetes<\/a>,\u00a0infectious diseases\u00a0(such as shingles<\/a>), and poisoning by toxins (such as heavy metals). PNS disorders often have symptoms\u00a0like\u00a0loss of feeling, tingling, burning sensations, or muscle weakness. If a traumatic injury results in a nerve being transected (cut all the way through), it may regenerate, but this is a very slow process and may take many months.<\/p>\nTwo other diseases of the PNS are Guillain-Barre syndrome and Charcot-Marie-Tooth disease.<\/p>\n
\n- Guillain-Barre syndrome<\/a> is a rare disease in which the immune system attacks nerves of the PNS, leading to muscle weakness and even paralysis. The exact cause of Guillain-Barre syndrome is unknown, but it often occurs after a viral or bacterial infection. There is no known cure for the syndrome, but most people eventually make a full recovery. Recovery can be slow, however, lasting anywhere from several weeks to several years.<\/li>\n
- Charcot-Marie-Tooth disease<\/a> is a hereditary disorder of the nerves, and one of the most common inherited neurological disorders. It affects predominantly the nerves in the feet and legs,\u00a0and often\u00a0in the hands and arms, as well. The disease is characterized by loss of muscle tissue and sense of touch. It is presently incurable.<\/li>\n<\/ul>\n\n
Feature: My\u00a0Human Body<\/h1>\n<\/div>\n
The autonomic nervous system is considered to be involuntary because it doesn’t require conscious input. However, it\u00a0is<\/em>\u00a0possible to exert some voluntary control over it. People who practice yoga or other so-called mind-body techniques, for example,\u00a0can\u00a0reduce their heart rate and certain other autonomic functions. Slowing down these otherwise involuntary responses is a good way to relieve stress and reduce the wear-and-tear that stress can place on the body. Such techniques may also be useful for controlling post-traumatic stress disorder and chronic pain. Three types of integrative practices for these purposes\u00a0are\u00a0breathing exercises, body-based tension modulation exercises, and mindfulness techniques.<\/p>\nBreathing exercises can help control the rapid, shallow breathing that often occurs when you are anxious or under stress. These exercises can be learned quickly, and they provide immediate feelings of relief. Specific breathing exercises include paced breath, diaphragmatic breathing, and Breathe2Relax or Chill Zone on MindShift\u2122 CBT, which are downloadable breathing practice mobile applications, or “Apps”. Try syncing your breathing with Eric Klassen’s “Triangle breathing, 1 minute” video:<\/p>\n
https:\/\/www.youtube.com\/watch?v=u9Q8D6n-3qw<\/p>\n
Triangle breathing, 1 minute, Erin Klassen, 2015.<\/p>\n
Body-based tension modulation exercises include yoga postures (also known as \u201casanas\u201d) and tension manipulation exercises. The latter include the Trauma\/Tension Release\u00a0Exercise\u00a0(TRE) and the Trauma Resiliency Model (TRM). Watch this video for a brief \u2014 but informative \u2014 introduction to the TRE program:<\/p>\n
https:\/\/www.youtube.com\/watch?v=67R974D8swM&feature=youtu.be<\/p>\n
TRE\u00ae : Tension and Trauma Releasing Exercises, an Introduction with Jessica Schaffer, Jessica Schaffer Nervous System RESET, 2015.<\/p>\n
Mindfulness techniques have been shown to reduce symptoms of depression, as well as those of anxiety and stress. They have also been shown to be useful for pain management and performance enhancement. Specific mindfulness programs include Mindfulness Based Stress Reduction (MBSR) and Mindfulness Mind-Fitness Training (MMFT). You can learn more about MBSR by watching the video below.<\/p>\n
Figure 8.6.3 In this diagram, each nerve is depicted as a single neuron for simplicity. This afferent neuron sends nerve impulses from sensory receptors in the skin to the CNS. The efferent neuron is a motor neuron that sends nerve impulses from the CNS to a muscle. The cell body of the afferent neuron is located in a ganglion (not pictured), while the cell body of the motor neuron is located in the spinal cord.<\/em>[\/caption]\r\n\r\n<\/div>\r\nDivisions of the Peripheral Nervous System<\/h1>\r\n<\/div>\r\nThe PNS is divided into two major systems, called the [pb_glossary id=\"5899\"]autonomic nervous system[\/pb_glossary] and the [pb_glossary id=\"3014\"]somatic nervous system[\/pb_glossary]. In the diagram\u00a0below, the autonomic system is shown on the left, and the somatic system on the right. Both systems of the PNS interact with the CNS and include sensory and motor neurons, but they use different\u00a0circuits\u00a0of nerves and ganglia.\r\n\r\n[caption id=\"attachment_3114\" align=\"aligncenter\" width=\"1075\"] Figure 8.6.4 The two major divisions of the PNS are the autonomic and sensory nervous systems.<\/em>[\/caption]\r\nSomatic Nervous System<\/h2>\r\nThe\u00a0[pb_glossary id=\"3014\"]somatic nervous system[\/pb_glossary]<\/strong>\u00a0primarily\u00a0senses\u00a0the external environment and controls voluntary activities about which decisions and commands come from the cerebral cortex of the brain. When you feel too warm, for example, you decide to turn on the air conditioner. As you walk across the room to the thermostat, you are using your somatic nervous system. In general, the somatic nervous system is responsible for all of your\u00a0conscious<\/em>\u00a0perceptions of the outside world, as well as all of the voluntary motor activities you perform in response. Whether it\u2019s playing a piano, driving a car, or playing basketball, you can thank your somatic nervous system for making it possible.\r\n\r\nSomatic sensory and motor information is transmitted through\u00a012 pairs of cranial nerves and 31 pairs of spinal nerves. Cranial nerves are in the head and neck and connect directly to the brain. Sensory components of cranial nerves\u00a0transmit information about\u00a0smells, tastes, light, sounds, and body position. Motor components of cranial nerves control\u00a0skeletal muscles\u00a0of the face, tongue, eyeballs, throat, head, and shoulders. Motor components of cranial nerves also control the salivary glands and swallowing. Four of the 12 cranial nerves participate in both sensory and motor functions as mixed nerves, having both sensory and motor neurons.\r\n\r\nSpinal nerves emanate from the spinal column between vertebrae. All of the spinal nerves are mixed nerves, containing both sensory and motor neurons. The areas of skin innervated by the 31 pairs of spinal nerves are shown in the figure\u00a0below. These include sensory nerves in the skin that sense pressure,\u00a0temperature, vibrations, and pain. Other sensory nerves are in the\u00a0muscles, and they sense stretching and tension. Spinal nerves also include motor nerves that stimulate\u00a0skeletal muscles\u00a0to contract, allowing for voluntary body movements.\r\n\r\n[caption id=\"attachment_3115\" align=\"aligncenter\" width=\"550\"] Figure 8.6.5 This drawing shows the areas of the skin innervated by sensory spinal nerves of the somatic nervous system. The left half of the figure shows the nerves in the front of the body, and the right half shows the nerves in the back of the body. The area that each spinal nerve innervates is shown in a different colour.<\/em>[\/caption]\r\nAutonomic Nervous System<\/h2>\r\nThe\u00a0[pb_glossary id=\"5899\"]autonomic nervous system[\/pb_glossary]<\/strong>\u00a0primarily\u00a0senses\u00a0the internal environment and controls involuntary activities. It is responsible for monitoring conditions in the internal environment and bringing about appropriate changes in them. In general, the\u00a0autonomic\u00a0nervous system is responsible for all the activities that go on inside your body\u00a0without<\/em>\u00a0your conscious awareness or voluntary participation.\r\n\r\nStructurally, the autonomic nervous system consists of sensory and motor nerves that run between the CNS (especially the hypothalamus in the brain), internal organs (such as the\u00a0heart, lungs, and digestive organs), and glands (such as the\u00a0pancreas\u00a0and sweat glands). [pb_glossary id=\"3030\"]Sensory neurons[\/pb_glossary] in the autonomic system detect internal body conditions and send messages to the brain. Motor nerves in the autonomic system affect appropriate responses by controlling contractions of smooth or cardiac muscle, or glandular tissue. For example, when sensory nerves of the autonomic system detect a rise in body\u00a0temperature, motor nerves signal smooth muscles in\u00a0blood vessels\u00a0near the body surface to undergo vasodilation, and the sweat glands in the skin to secrete more sweat to cool the body.\r\n\r\nThe autonomic nervous system, in turn, has three subdivisions: the [pb_glossary id=\"3015\"]sympathetic division[\/pb_glossary], [pb_glossary id=\"3016\"]parasympathetic division[\/pb_glossary], and [pb_glossary id=\"5987\"]enteric division[\/pb_glossary]. The first two subdivisions of the autonomic system are summarized in the figure\u00a0below. Both affect the same organs and glands, but they generally do so in opposite ways.\r\n\r\n \t- The\u00a0sympathetic division<\/strong>\u00a0controls the fight-or-flight response. Changes occur in organs and glands throughout the body that prepare the body to fight or flee in response to a perceived danger. For example, the\u00a0heart\u00a0rate speeds up, air passages in the lungs become wider, more\u00a0blood\u00a0flows to the\u00a0skeletal muscles, and the\u00a0digestive system temporarily shuts down.<\/li>\r\n \t
- The\u00a0parasympathetic division<\/strong>\u00a0returns the body to normal after the fight-or-flight response has occurred. For example, it slows down the\u00a0heart\u00a0rate, narrows air passages in the lungs, reduces\u00a0blood\u00a0flow to the skeletal muscles, and stimulates the\u00a0digestive system\u00a0to start working again. The parasympathetic division also maintains internal\u00a0homeostasis\u00a0of the body at other times.<\/li>\r\n \t
- The\u00a0enteric division<\/strong> is made up of nerve fibres that supply the organs of the digestive system. This division allows for the local control of many digestive functions.<\/li>\r\n<\/ul>\r\n[caption id=\"attachment_3116\" align=\"aligncenter\" width=\"597\"] Figure 8.6.6 This diagram summarizes the structures and functions controlled by the parasympathetic and sympathetic divisions of the autonomic nervous system.<\/em>[\/caption]\r\n\r\nDisorders of the Peripheral Nervous System<\/span>\r\n\r\nUnlike the CNS \u2014 which is protected by\u00a0[pb_glossary id=\"5913\"]bone[\/pb_glossary]s, [pb_glossary id=\"2929\"]meninges[\/pb_glossary], and [pb_glossary id=\"5939\"]cerebrospinal fluid[\/pb_glossary] \u2014 the PNS has no such protections. The PNS also has no blood-brain barrier to protect it from toxins and pathogens in the\u00a0blood. Therefore, the PNS is more subject to injury and disease than is the CNS. Causes of nerve injury include\u00a0diabetes<\/a>,\u00a0infectious diseases\u00a0(such as shingles<\/a>), and poisoning by toxins (such as heavy metals). PNS disorders often have symptoms\u00a0like\u00a0loss of feeling, tingling, burning sensations, or muscle weakness. If a traumatic injury results in a nerve being transected (cut all the way through), it may regenerate, but this is a very slow process and may take many months.\r\n\r\nTwo other diseases of the PNS are Guillain-Barre syndrome and Charcot-Marie-Tooth disease.\r\n
\r\n \t- Guillain-Barre syndrome<\/a> is a rare disease in which the immune system attacks nerves of the PNS, leading to muscle weakness and even paralysis. The exact cause of Guillain-Barre syndrome is unknown, but it often occurs after a viral or bacterial infection. There is no known cure for the syndrome, but most people eventually make a full recovery. Recovery can be slow, however, lasting anywhere from several weeks to several years.<\/li>\r\n \t
- Charcot-Marie-Tooth disease<\/a> is a hereditary disorder of the nerves, and one of the most common inherited neurological disorders. It affects predominantly the nerves in the feet and legs,\u00a0and often\u00a0in the hands and arms, as well. The disease is characterized by loss of muscle tissue and sense of touch. It is presently incurable.<\/li>\r\n<\/ul>\r\n\r\n
Feature: My\u00a0Human Body<\/h1>\r\n<\/div>\r\nThe autonomic nervous system is considered to be involuntary because it doesn't require conscious input. However, it\u00a0is<\/em>\u00a0possible to exert some voluntary control over it. People who practice yoga or other so-called mind-body techniques, for example,\u00a0can\u00a0reduce their heart rate and certain other autonomic functions. Slowing down these otherwise involuntary responses is a good way to relieve stress and reduce the wear-and-tear that stress can place on the body. Such techniques may also be useful for controlling post-traumatic stress disorder and chronic pain. Three types of integrative practices for these purposes\u00a0are\u00a0breathing exercises, body-based tension modulation exercises, and mindfulness techniques.\r\n\r\nBreathing exercises can help control the rapid, shallow breathing that often occurs when you are anxious or under stress. These exercises can be learned quickly, and they provide immediate feelings of relief. Specific breathing exercises include paced breath, diaphragmatic breathing, and Breathe2Relax or Chill Zone on MindShift\u2122 CBT, which are downloadable breathing practice mobile applications, or \"Apps\". Try syncing your breathing with Eric Klassen's \"Triangle breathing, 1 minute\" video:\r\n\r\nhttps:\/\/www.youtube.com\/watch?v=u9Q8D6n-3qw\r\nTriangle breathing, 1 minute, Erin Klassen, 2015.<\/p>\r\nBody-based tension modulation exercises include yoga postures (also known as \u201casanas\u201d) and tension manipulation exercises. The latter include the Trauma\/Tension Release\u00a0Exercise\u00a0(TRE) and the Trauma Resiliency Model (TRM). Watch this video for a brief \u2014 but informative \u2014 introduction to the TRE program:\r\n\r\nhttps:\/\/www.youtube.com\/watch?v=67R974D8swM&feature=youtu.be\r\n
TRE\u00ae : Tension and Trauma Releasing Exercises, an Introduction with Jessica Schaffer, Jessica Schaffer Nervous System RESET, 2015.<\/p>\r\nMindfulness techniques have been shown to reduce symptoms of depression, as well as those of anxiety and stress. They have also been shown to be useful for pain management and performance enhancement. Specific mindfulness programs include Mindfulness Based Stress Reduction (MBSR) and Mindfulness Mind-Fitness Training (MMFT). You can learn more about MBSR by watching the video below.\r\n\r\nhttps:\/\/www.youtube.com\/watch?v=0TA7P-iCCcY&feature=youtu.be\r\n
Mindfulness-Based Stress Reduction (UMass Medical School, Center for Mindfulness), Palouse Mindfulness, 2017.<\/p>\r\n\r\n
\r\n8.6 Summary<\/span><\/h1>\r\n<\/header>\r\n\r\n\r\n \t- The [pb_glossary id=\"3009\"]peripheral nervous system[\/pb_glossary] (PNS) consists of all the nervous tissue that lies outside the\u00a0[pb_glossary id=\"5933\"]central nervous system[\/pb_glossary] (CNS). Its main function is to connect the CNS to the rest of the organism.<\/li>\r\n \t
- The PNS is made up of [pb_glossary id=\"3011\"]nerves[\/pb_glossary] and [pb_glossary id=\"6027\"]ganglia[\/pb_glossary]. Nerves are bundles of [pb_glossary id=\"5901\"]axons[\/pb_glossary], and ganglia are groups of [pb_glossary id=\"5931\"]cell bodies[\/pb_glossary]. Nerves are classified as sensory, motor, or a mix of the two.<\/li>\r\n \t
- The PNS is divided into the [pb_glossary id=\"3014\"]somatic[\/pb_glossary] and [pb_glossary id=\"5899\"]autonomic nervous systems[\/pb_glossary]. The somatic system controls [pb_glossary id=\"3004\"]voluntary[\/pb_glossary] activities, whereas the autonomic system controls [pb_glossary id=\"3005\"]involuntary[\/pb_glossary] activities.<\/li>\r\n \t
- The autonomic nervous system is further divided into [pb_glossary id=\"3015\"]sympathetic[\/pb_glossary], [pb_glossary id=\"3016\"]parasympathetic[\/pb_glossary], and [pb_glossary id=\"5987\"]enteric divisions[\/pb_glossary]. The sympathetic division controls [pb_glossary id=\"6013\"]fight-or-flight responses[\/pb_glossary]\u00a0during emergencies, the parasympathetic system controls routine body functions the rest of the time, and the enteric division provides local control over the [pb_glossary id=\"5969\"]digestive system[\/pb_glossary].<\/li>\r\n \t
- The PNS is not as well protected physically or chemically as the CNS, so it is more prone to injury and disease. PNS problems include injury from\u00a0diabetes, shingles, and heavy metal poisoning. Two disorders of the PNS are Guillain-Barre syndrome and Charcot-Marie-Tooth disease.<\/li>\r\n<\/ul>\r\n<\/div>\r\n<\/div>\r\n
\r\n8.6 Review Questions<\/span><\/h1>\r\n<\/header>\r\n\r\n\r\n \t- Describe the general structure of the peripheral nervous system. State its primary function.<\/li>\r\n \t
- What are ganglia?<\/li>\r\n \t
- Identify three types of nerves based on the direction in which they carry\u00a0nerve impulses.<\/li>\r\n \t
- Outline all of the divisions of the peripheral nervous system.<\/li>\r\n \t
- Compare and contrast the somatic and autonomic nervous systems.<\/li>\r\n \t
- When and how does the sympathetic division of the autonomic nervous system affect the body?<\/li>\r\n \t
- What is the function of the parasympathetic division of the autonomic nervous system?\u00a0Specifically, how does it affect the body?<\/li>\r\n \t
- Name and describe two peripheral nervous system disorders.<\/li>\r\n \t
- Give one example of how the CNS interacts with the PNS to control a function in the body.<\/li>\r\n \t
- For each of the following types of information, identify whether the neuron carrying it is sensory or motor, and whether it is most likely in the somatic or autonomic nervous system:\r\n
\r\n \t- Visual information<\/li>\r\n \t
- Blood pressure information<\/li>\r\n \t
- Information that causes muscle contraction in digestive organs after eating<\/li>\r\n \t
- Information that causes muscle contraction in skeletal muscles based on the person\u2019s decision to make a movement<\/li>\r\n<\/ol>\r\n<\/li>\r\n \t
- [h5p id=\"564\"]<\/li>\r\n<\/ol>\r\n<\/div>\r\n<\/div>\r\n
\r\n8.6 Explore More<\/span><\/h1>\r\n<\/header>\r\n\r\n\r\nhttps:\/\/www.youtube.com\/watch?v=ySIDMU2cy0Y&feature=emb_logo\r\nPhantom Limbs Explained, Plethrons, 2015.<\/p>\r\nhttps:\/\/www.youtube.com\/watch?time_continue=1&v=73yo5nJne6c&feature=emb_logo\r\n
Why Do Hot Peppers Cause Pain? Reactions, 2015.<\/p>\r\n\r\n<\/div>\r\n<\/div>\r\n
Attributions<\/h2>\r\nFigure 8.6.1<\/strong>\r\n\r\nKid\u2019s piant duet<\/a> by\u00a0PJMixer<\/a> on Flickr<\/a> is used under a CC BY-NC-ND 2.0<\/a>\u00a0(https:\/\/creativecommons.org\/licenses\/by-nc-nd\/2.0\/) license.\r\n\r\nFigure 8.6.2<\/strong>\r\n\r\nNervous_system_diagram<\/a> by \u00a4~Persian Poet Gal<\/span><\/span><\/a>\u00a0 on Wikimedia Commons is released into the public domain<\/a> (https:\/\/en.wikipedia.org\/wiki\/Public_domain).\r\n\r\n\r\nFigure 8.6.3<\/strong>\r\n\r\nAfferent_and_efferent_neurons_en.svg<\/a> by Helixitta<\/a> on Wikimedia Commons is used under a CC BY-SA 4.0 <\/a>\u00a0 (https:\/\/creativecommons.org\/licenses\/by-sa\/4.0) license.\r\n\r\nFigure 8.6.4<\/strong>\r\n\r\nAutonomic and Somatic Nervous System<\/a> by Christinelmiller<\/a> on Wikimedia Commons is used under a CC BY-SA 4.0<\/a> (https:\/\/creativecommons.org\/licenses\/by-sa\/4.0) license.\r\n\r\nFigure 8.6.5<\/strong>\r\n\r\nDermatoms.svg<\/a> by Ralf Stephan (mailto:ralf@ark.in-berlin.de) on Wikimedia Commons is released into the public domain<\/a> (https:\/\/en.wikipedia.org\/wiki\/Public_domain).\r\n\r\nFigure 8.6.6<\/strong>\r\n\r\nThe_Autonomic_Nervous_System<\/a> by Geo-Science-International<\/a> on Wikimedia Commons is used and adapted by Christine Miller under a\u00a0CC0 1.0<\/a> Universal\r\nPublic Domain Dedication license (https:\/\/creativecommons.org\/publicdomain\/zero\/1.0\/).\r\nReferences<\/h2>\r\n
Erin Klassen. (2015, December 15). Triangle breathing, 1 minute. YouTube. https:\/\/www.youtube.com\/watch?v=u9Q8D6n-3qw&feature=youtu.be<\/p>\r\n
Jessica Schaffer Nervous System RESET. (2015, January 15). TRE\u00ae : Tension and trauma releasing exercises, an Introduction with Jessica Schaffer. YouTube. https:\/\/www.youtube.com\/watch?v=67R974D8swM&feature=youtu.be<\/p>\r\n
Mayo Clinic Staff. (n.d.). Charcot-Marie-Tooth disease [online article]. MayoClinic.org. https:\/\/www.mayoclinic.org\/diseases-conditions\/charcot-marie-tooth-disease\/symptoms-causes\/syc-20350517<\/p>\r\n
Mayo Clinic Staff. (n.d.). Diabetes [online article]. MayoClinic.org. https:\/\/www.mayoclinic.org\/diseases-conditions\/diabetes\/symptoms-causes\/syc-20371444<\/p>\r\n
Mayo Clinic Staff. (n.d.). Guillain-Barre syndrome [online article]. MayoClinic.org. https:\/\/www.mayoclinic.org\/diseases-conditions\/guillain-barre-syndrome\/symptoms-causes\/syc-20362793<\/p>\r\n
Mayo Clinic Staff. (n.d.). Shingles [online article]. MayoClinic.org. https:\/\/www.mayoclinic.org\/diseases-conditions\/shingles\/symptoms-causes\/syc-20353054<\/p>\r\n
Mayo Clinic Staff. (n.d.). Stroke [online article]. MayoClinic.org. https:\/\/www.mayoclinic.org\/diseases-conditions\/stroke\/symptoms-causes\/syc-20350113<\/p>\r\n
Palouse Mindfulness. (2017, March 25).\u00a0 Mindfulness-based stress reduction (UMass Medical School, Center for Mindfulness), YouTube. https:\/\/www.youtube.com\/watch?v=0TA7P-iCCcY&feature=youtu.be<\/p>\r\n
Plethrons, (2015, March 23). Phantom limbs explained. YouTube. https:\/\/www.youtube.com\/watch?v=ySIDMU2cy0Y&feature=youtu.be<\/p>\r\n
Reactions. (2015, December 1). Why do hot peppers cause pain? YouTube. https:\/\/www.youtube.com\/watch?v=73yo5nJne6c&feature=youtu.be<\/p>\r\n \r\n\r\n \r\n\r\n ","rendered":"
<\/p>\nFigure 8.6.1 A duet with the peripheral nervous system.\u00a0<\/em><\/figcaption><\/figure>\nOne Piano, Four Hands<\/h1>\n
Did you ever see two people play the same piano? How do they coordinate all the movements of their own fingers \u2014 let alone synchronize them with those of their partner? The peripheral nervous system plays an important part in this challenge.<\/p>\n
\nWhat Is the Peripheral Nervous System?<\/h1>\n<\/div>\n
The\u00a0peripheral nervous system<\/a> (PNS)<\/strong>\u00a0consists of all the nervous tissue that lies outside of the\u00a0central nervous system<\/a>\u00a0(CNS). The main function of the PNS is to connect the CNS to the rest of the organism. It serves as a\u00a0communication\u00a0relay, going back and forth between the CNS and\u00a0muscles, organs, and glands throughout the body.<\/p>\nFigure 8.6.2 The nerves of the peripheral nervous system are shown in blue in this diagram.<\/em><\/figcaption><\/figure>\n<\/div>\n\nTissues of the Peripheral Nervous System<\/h1>\n<\/div>\n
The PNS is mostly made up of cable-like bundles of axons called\u00a0nerves<\/a><\/strong>,\u00a0as well as\u00a0clusters of neuronal cell bodies called\u00a0ganglia<\/a><\/strong>\u00a0(singular,\u00a0ganglion<\/a><\/strong>). Nerves are generally classified\u00a0as sensory, motor, or mixed nerves\u00a0based on\u00a0the direction in which they carry\u00a0nerve impulses.<\/p>\n\n- Sensory nerves<\/strong>\u00a0transmit information from sensory receptors in the body to the CNS. Sensory nerves are also called afferent nerves. You can see an example in the figure\u00a0below.<\/li>\n
- Motor nerves<\/a><\/strong>\u00a0transmit information from the CNS to\u00a0muscles, organs, and glands. Motor nerves are also called efferent nerves. You can see one in the figure\u00a0below.<\/li>\n
- Mixed nerves<\/a><\/strong>\u00a0contain both sensory and motor neurons, so they can transmit information in both directions. They have both afferent and efferent functions.<\/li>\n<\/ul>\n
<\/p>\n
\nFigure 8.6.3 In this diagram, each nerve is depicted as a single neuron for simplicity. This afferent neuron sends nerve impulses from sensory receptors in the skin to the CNS. The efferent neuron is a motor neuron that sends nerve impulses from the CNS to a muscle. The cell body of the afferent neuron is located in a ganglion (not pictured), while the cell body of the motor neuron is located in the spinal cord.<\/em><\/figcaption><\/figure>\n<\/div>\n\nDivisions of the Peripheral Nervous System<\/h1>\n<\/div>\n
The PNS is divided into two major systems, called the autonomic nervous system<\/a> and the somatic nervous system<\/a>. In the diagram\u00a0below, the autonomic system is shown on the left, and the somatic system on the right. Both systems of the PNS interact with the CNS and include sensory and motor neurons, but they use different\u00a0circuits\u00a0of nerves and ganglia.<\/p>\nFigure 8.6.4 The two major divisions of the PNS are the autonomic and sensory nervous systems.<\/em><\/figcaption><\/figure>\nSomatic Nervous System<\/h2>\n
The\u00a0somatic nervous system<\/a><\/strong>\u00a0primarily\u00a0senses\u00a0the external environment and controls voluntary activities about which decisions and commands come from the cerebral cortex of the brain. When you feel too warm, for example, you decide to turn on the air conditioner. As you walk across the room to the thermostat, you are using your somatic nervous system. In general, the somatic nervous system is responsible for all of your\u00a0conscious<\/em>\u00a0perceptions of the outside world, as well as all of the voluntary motor activities you perform in response. Whether it\u2019s playing a piano, driving a car, or playing basketball, you can thank your somatic nervous system for making it possible.<\/p>\nSomatic sensory and motor information is transmitted through\u00a012 pairs of cranial nerves and 31 pairs of spinal nerves. Cranial nerves are in the head and neck and connect directly to the brain. Sensory components of cranial nerves\u00a0transmit information about\u00a0smells, tastes, light, sounds, and body position. Motor components of cranial nerves control\u00a0skeletal muscles\u00a0of the face, tongue, eyeballs, throat, head, and shoulders. Motor components of cranial nerves also control the salivary glands and swallowing. Four of the 12 cranial nerves participate in both sensory and motor functions as mixed nerves, having both sensory and motor neurons.<\/p>\n
Spinal nerves emanate from the spinal column between vertebrae. All of the spinal nerves are mixed nerves, containing both sensory and motor neurons. The areas of skin innervated by the 31 pairs of spinal nerves are shown in the figure\u00a0below. These include sensory nerves in the skin that sense pressure,\u00a0temperature, vibrations, and pain. Other sensory nerves are in the\u00a0muscles, and they sense stretching and tension. Spinal nerves also include motor nerves that stimulate\u00a0skeletal muscles\u00a0to contract, allowing for voluntary body movements.<\/p>\nFigure 8.6.5 This drawing shows the areas of the skin innervated by sensory spinal nerves of the somatic nervous system. The left half of the figure shows the nerves in the front of the body, and the right half shows the nerves in the back of the body. The area that each spinal nerve innervates is shown in a different colour.<\/em><\/figcaption><\/figure>\nAutonomic Nervous System<\/h2>\n
The\u00a0autonomic nervous system<\/a><\/strong>\u00a0primarily\u00a0senses\u00a0the internal environment and controls involuntary activities. It is responsible for monitoring conditions in the internal environment and bringing about appropriate changes in them. In general, the\u00a0autonomic\u00a0nervous system is responsible for all the activities that go on inside your body\u00a0without<\/em>\u00a0your conscious awareness or voluntary participation.<\/p>\nStructurally, the autonomic nervous system consists of sensory and motor nerves that run between the CNS (especially the hypothalamus in the brain), internal organs (such as the\u00a0heart, lungs, and digestive organs), and glands (such as the\u00a0pancreas\u00a0and sweat glands). Sensory neurons<\/a> in the autonomic system detect internal body conditions and send messages to the brain. Motor nerves in the autonomic system affect appropriate responses by controlling contractions of smooth or cardiac muscle, or glandular tissue. For example, when sensory nerves of the autonomic system detect a rise in body\u00a0temperature, motor nerves signal smooth muscles in\u00a0blood vessels\u00a0near the body surface to undergo vasodilation, and the sweat glands in the skin to secrete more sweat to cool the body.<\/p>\nThe autonomic nervous system, in turn, has three subdivisions: the sympathetic division<\/a>, parasympathetic division<\/a>, and enteric division<\/a>. The first two subdivisions of the autonomic system are summarized in the figure\u00a0below. Both affect the same organs and glands, but they generally do so in opposite ways.<\/p>\n\n- The\u00a0sympathetic division<\/strong>\u00a0controls the fight-or-flight response. Changes occur in organs and glands throughout the body that prepare the body to fight or flee in response to a perceived danger. For example, the\u00a0heart\u00a0rate speeds up, air passages in the lungs become wider, more\u00a0blood\u00a0flows to the\u00a0skeletal muscles, and the\u00a0digestive system temporarily shuts down.<\/li>\n
- The\u00a0parasympathetic division<\/strong>\u00a0returns the body to normal after the fight-or-flight response has occurred. For example, it slows down the\u00a0heart\u00a0rate, narrows air passages in the lungs, reduces\u00a0blood\u00a0flow to the skeletal muscles, and stimulates the\u00a0digestive system\u00a0to start working again. The parasympathetic division also maintains internal\u00a0homeostasis\u00a0of the body at other times.<\/li>\n
- The\u00a0enteric division<\/strong> is made up of nerve fibres that supply the organs of the digestive system. This division allows for the local control of many digestive functions.<\/li>\n<\/ul>\n
Figure 8.6.6 This diagram summarizes the structures and functions controlled by the parasympathetic and sympathetic divisions of the autonomic nervous system.<\/em><\/figcaption><\/figure>\nDisorders of the Peripheral Nervous System<\/span><\/p>\nUnlike the CNS \u2014 which is protected by\u00a0bone<\/a>s, meninges<\/a>, and cerebrospinal fluid<\/a> \u2014 the PNS has no such protections. The PNS also has no blood-brain barrier to protect it from toxins and pathogens in the\u00a0blood. Therefore, the PNS is more subject to injury and disease than is the CNS. Causes of nerve injury include\u00a0diabetes<\/a>,\u00a0infectious diseases\u00a0(such as shingles<\/a>), and poisoning by toxins (such as heavy metals). PNS disorders often have symptoms\u00a0like\u00a0loss of feeling, tingling, burning sensations, or muscle weakness. If a traumatic injury results in a nerve being transected (cut all the way through), it may regenerate, but this is a very slow process and may take many months.<\/p>\nTwo other diseases of the PNS are Guillain-Barre syndrome and Charcot-Marie-Tooth disease.<\/p>\n
\n- Guillain-Barre syndrome<\/a> is a rare disease in which the immune system attacks nerves of the PNS, leading to muscle weakness and even paralysis. The exact cause of Guillain-Barre syndrome is unknown, but it often occurs after a viral or bacterial infection. There is no known cure for the syndrome, but most people eventually make a full recovery. Recovery can be slow, however, lasting anywhere from several weeks to several years.<\/li>\n
- Charcot-Marie-Tooth disease<\/a> is a hereditary disorder of the nerves, and one of the most common inherited neurological disorders. It affects predominantly the nerves in the feet and legs,\u00a0and often\u00a0in the hands and arms, as well. The disease is characterized by loss of muscle tissue and sense of touch. It is presently incurable.<\/li>\n<\/ul>\n\n
Feature: My\u00a0Human Body<\/h1>\n<\/div>\n
The autonomic nervous system is considered to be involuntary because it doesn’t require conscious input. However, it\u00a0is<\/em>\u00a0possible to exert some voluntary control over it. People who practice yoga or other so-called mind-body techniques, for example,\u00a0can\u00a0reduce their heart rate and certain other autonomic functions. Slowing down these otherwise involuntary responses is a good way to relieve stress and reduce the wear-and-tear that stress can place on the body. Such techniques may also be useful for controlling post-traumatic stress disorder and chronic pain. Three types of integrative practices for these purposes\u00a0are\u00a0breathing exercises, body-based tension modulation exercises, and mindfulness techniques.<\/p>\nBreathing exercises can help control the rapid, shallow breathing that often occurs when you are anxious or under stress. These exercises can be learned quickly, and they provide immediate feelings of relief. Specific breathing exercises include paced breath, diaphragmatic breathing, and Breathe2Relax or Chill Zone on MindShift\u2122 CBT, which are downloadable breathing practice mobile applications, or “Apps”. Try syncing your breathing with Eric Klassen’s “Triangle breathing, 1 minute” video:<\/p>\n
https:\/\/www.youtube.com\/watch?v=u9Q8D6n-3qw<\/p>\n
Triangle breathing, 1 minute, Erin Klassen, 2015.<\/p>\n
Body-based tension modulation exercises include yoga postures (also known as \u201casanas\u201d) and tension manipulation exercises. The latter include the Trauma\/Tension Release\u00a0Exercise\u00a0(TRE) and the Trauma Resiliency Model (TRM). Watch this video for a brief \u2014 but informative \u2014 introduction to the TRE program:<\/p>\n
https:\/\/www.youtube.com\/watch?v=67R974D8swM&feature=youtu.be<\/p>\n
TRE\u00ae : Tension and Trauma Releasing Exercises, an Introduction with Jessica Schaffer, Jessica Schaffer Nervous System RESET, 2015.<\/p>\n
Mindfulness techniques have been shown to reduce symptoms of depression, as well as those of anxiety and stress. They have also been shown to be useful for pain management and performance enhancement. Specific mindfulness programs include Mindfulness Based Stress Reduction (MBSR) and Mindfulness Mind-Fitness Training (MMFT). You can learn more about MBSR by watching the video below.<\/p>\n
Figure 8.6.5 This drawing shows the areas of the skin innervated by sensory spinal nerves of the somatic nervous system. The left half of the figure shows the nerves in the front of the body, and the right half shows the nerves in the back of the body. The area that each spinal nerve innervates is shown in a different colour.<\/em>[\/caption]\r\nAutonomic Nervous System<\/h2>\r\nThe\u00a0[pb_glossary id=\"5899\"]autonomic nervous system[\/pb_glossary]<\/strong>\u00a0primarily\u00a0senses\u00a0the internal environment and controls involuntary activities. It is responsible for monitoring conditions in the internal environment and bringing about appropriate changes in them. In general, the\u00a0autonomic\u00a0nervous system is responsible for all the activities that go on inside your body\u00a0without<\/em>\u00a0your conscious awareness or voluntary participation.\r\n\r\nStructurally, the autonomic nervous system consists of sensory and motor nerves that run between the CNS (especially the hypothalamus in the brain), internal organs (such as the\u00a0heart, lungs, and digestive organs), and glands (such as the\u00a0pancreas\u00a0and sweat glands). [pb_glossary id=\"3030\"]Sensory neurons[\/pb_glossary] in the autonomic system detect internal body conditions and send messages to the brain. Motor nerves in the autonomic system affect appropriate responses by controlling contractions of smooth or cardiac muscle, or glandular tissue. For example, when sensory nerves of the autonomic system detect a rise in body\u00a0temperature, motor nerves signal smooth muscles in\u00a0blood vessels\u00a0near the body surface to undergo vasodilation, and the sweat glands in the skin to secrete more sweat to cool the body.\r\n\r\nThe autonomic nervous system, in turn, has three subdivisions: the [pb_glossary id=\"3015\"]sympathetic division[\/pb_glossary], [pb_glossary id=\"3016\"]parasympathetic division[\/pb_glossary], and [pb_glossary id=\"5987\"]enteric division[\/pb_glossary]. The first two subdivisions of the autonomic system are summarized in the figure\u00a0below. Both affect the same organs and glands, but they generally do so in opposite ways.\r\n\r\n \t- The\u00a0sympathetic division<\/strong>\u00a0controls the fight-or-flight response. Changes occur in organs and glands throughout the body that prepare the body to fight or flee in response to a perceived danger. For example, the\u00a0heart\u00a0rate speeds up, air passages in the lungs become wider, more\u00a0blood\u00a0flows to the\u00a0skeletal muscles, and the\u00a0digestive system temporarily shuts down.<\/li>\r\n \t
- The\u00a0parasympathetic division<\/strong>\u00a0returns the body to normal after the fight-or-flight response has occurred. For example, it slows down the\u00a0heart\u00a0rate, narrows air passages in the lungs, reduces\u00a0blood\u00a0flow to the skeletal muscles, and stimulates the\u00a0digestive system\u00a0to start working again. The parasympathetic division also maintains internal\u00a0homeostasis\u00a0of the body at other times.<\/li>\r\n \t
- The\u00a0enteric division<\/strong> is made up of nerve fibres that supply the organs of the digestive system. This division allows for the local control of many digestive functions.<\/li>\r\n<\/ul>\r\n[caption id=\"attachment_3116\" align=\"aligncenter\" width=\"597\"] Figure 8.6.6 This diagram summarizes the structures and functions controlled by the parasympathetic and sympathetic divisions of the autonomic nervous system.<\/em>[\/caption]\r\n\r\nDisorders of the Peripheral Nervous System<\/span>\r\n\r\nUnlike the CNS \u2014 which is protected by\u00a0[pb_glossary id=\"5913\"]bone[\/pb_glossary]s, [pb_glossary id=\"2929\"]meninges[\/pb_glossary], and [pb_glossary id=\"5939\"]cerebrospinal fluid[\/pb_glossary] \u2014 the PNS has no such protections. The PNS also has no blood-brain barrier to protect it from toxins and pathogens in the\u00a0blood. Therefore, the PNS is more subject to injury and disease than is the CNS. Causes of nerve injury include\u00a0diabetes<\/a>,\u00a0infectious diseases\u00a0(such as shingles<\/a>), and poisoning by toxins (such as heavy metals). PNS disorders often have symptoms\u00a0like\u00a0loss of feeling, tingling, burning sensations, or muscle weakness. If a traumatic injury results in a nerve being transected (cut all the way through), it may regenerate, but this is a very slow process and may take many months.\r\n\r\nTwo other diseases of the PNS are Guillain-Barre syndrome and Charcot-Marie-Tooth disease.\r\n
\r\n \t- Guillain-Barre syndrome<\/a> is a rare disease in which the immune system attacks nerves of the PNS, leading to muscle weakness and even paralysis. The exact cause of Guillain-Barre syndrome is unknown, but it often occurs after a viral or bacterial infection. There is no known cure for the syndrome, but most people eventually make a full recovery. Recovery can be slow, however, lasting anywhere from several weeks to several years.<\/li>\r\n \t
- Charcot-Marie-Tooth disease<\/a> is a hereditary disorder of the nerves, and one of the most common inherited neurological disorders. It affects predominantly the nerves in the feet and legs,\u00a0and often\u00a0in the hands and arms, as well. The disease is characterized by loss of muscle tissue and sense of touch. It is presently incurable.<\/li>\r\n<\/ul>\r\n\r\n
Feature: My\u00a0Human Body<\/h1>\r\n<\/div>\r\nThe autonomic nervous system is considered to be involuntary because it doesn't require conscious input. However, it\u00a0is<\/em>\u00a0possible to exert some voluntary control over it. People who practice yoga or other so-called mind-body techniques, for example,\u00a0can\u00a0reduce their heart rate and certain other autonomic functions. Slowing down these otherwise involuntary responses is a good way to relieve stress and reduce the wear-and-tear that stress can place on the body. Such techniques may also be useful for controlling post-traumatic stress disorder and chronic pain. Three types of integrative practices for these purposes\u00a0are\u00a0breathing exercises, body-based tension modulation exercises, and mindfulness techniques.\r\n\r\nBreathing exercises can help control the rapid, shallow breathing that often occurs when you are anxious or under stress. These exercises can be learned quickly, and they provide immediate feelings of relief. Specific breathing exercises include paced breath, diaphragmatic breathing, and Breathe2Relax or Chill Zone on MindShift\u2122 CBT, which are downloadable breathing practice mobile applications, or \"Apps\". Try syncing your breathing with Eric Klassen's \"Triangle breathing, 1 minute\" video:\r\n\r\nhttps:\/\/www.youtube.com\/watch?v=u9Q8D6n-3qw\r\nTriangle breathing, 1 minute, Erin Klassen, 2015.<\/p>\r\nBody-based tension modulation exercises include yoga postures (also known as \u201casanas\u201d) and tension manipulation exercises. The latter include the Trauma\/Tension Release\u00a0Exercise\u00a0(TRE) and the Trauma Resiliency Model (TRM). Watch this video for a brief \u2014 but informative \u2014 introduction to the TRE program:\r\n\r\nhttps:\/\/www.youtube.com\/watch?v=67R974D8swM&feature=youtu.be\r\n
TRE\u00ae : Tension and Trauma Releasing Exercises, an Introduction with Jessica Schaffer, Jessica Schaffer Nervous System RESET, 2015.<\/p>\r\nMindfulness techniques have been shown to reduce symptoms of depression, as well as those of anxiety and stress. They have also been shown to be useful for pain management and performance enhancement. Specific mindfulness programs include Mindfulness Based Stress Reduction (MBSR) and Mindfulness Mind-Fitness Training (MMFT). You can learn more about MBSR by watching the video below.\r\n\r\nhttps:\/\/www.youtube.com\/watch?v=0TA7P-iCCcY&feature=youtu.be\r\n
Mindfulness-Based Stress Reduction (UMass Medical School, Center for Mindfulness), Palouse Mindfulness, 2017.<\/p>\r\n\r\n
\r\n8.6 Summary<\/span><\/h1>\r\n<\/header>\r\n\r\n\r\n \t- The [pb_glossary id=\"3009\"]peripheral nervous system[\/pb_glossary] (PNS) consists of all the nervous tissue that lies outside the\u00a0[pb_glossary id=\"5933\"]central nervous system[\/pb_glossary] (CNS). Its main function is to connect the CNS to the rest of the organism.<\/li>\r\n \t
- The PNS is made up of [pb_glossary id=\"3011\"]nerves[\/pb_glossary] and [pb_glossary id=\"6027\"]ganglia[\/pb_glossary]. Nerves are bundles of [pb_glossary id=\"5901\"]axons[\/pb_glossary], and ganglia are groups of [pb_glossary id=\"5931\"]cell bodies[\/pb_glossary]. Nerves are classified as sensory, motor, or a mix of the two.<\/li>\r\n \t
- The PNS is divided into the [pb_glossary id=\"3014\"]somatic[\/pb_glossary] and [pb_glossary id=\"5899\"]autonomic nervous systems[\/pb_glossary]. The somatic system controls [pb_glossary id=\"3004\"]voluntary[\/pb_glossary] activities, whereas the autonomic system controls [pb_glossary id=\"3005\"]involuntary[\/pb_glossary] activities.<\/li>\r\n \t
- The autonomic nervous system is further divided into [pb_glossary id=\"3015\"]sympathetic[\/pb_glossary], [pb_glossary id=\"3016\"]parasympathetic[\/pb_glossary], and [pb_glossary id=\"5987\"]enteric divisions[\/pb_glossary]. The sympathetic division controls [pb_glossary id=\"6013\"]fight-or-flight responses[\/pb_glossary]\u00a0during emergencies, the parasympathetic system controls routine body functions the rest of the time, and the enteric division provides local control over the [pb_glossary id=\"5969\"]digestive system[\/pb_glossary].<\/li>\r\n \t
- The PNS is not as well protected physically or chemically as the CNS, so it is more prone to injury and disease. PNS problems include injury from\u00a0diabetes, shingles, and heavy metal poisoning. Two disorders of the PNS are Guillain-Barre syndrome and Charcot-Marie-Tooth disease.<\/li>\r\n<\/ul>\r\n<\/div>\r\n<\/div>\r\n
\r\n8.6 Review Questions<\/span><\/h1>\r\n<\/header>\r\n\r\n\r\n \t- Describe the general structure of the peripheral nervous system. State its primary function.<\/li>\r\n \t
- What are ganglia?<\/li>\r\n \t
- Identify three types of nerves based on the direction in which they carry\u00a0nerve impulses.<\/li>\r\n \t
- Outline all of the divisions of the peripheral nervous system.<\/li>\r\n \t
- Compare and contrast the somatic and autonomic nervous systems.<\/li>\r\n \t
- When and how does the sympathetic division of the autonomic nervous system affect the body?<\/li>\r\n \t
- What is the function of the parasympathetic division of the autonomic nervous system?\u00a0Specifically, how does it affect the body?<\/li>\r\n \t
- Name and describe two peripheral nervous system disorders.<\/li>\r\n \t
- Give one example of how the CNS interacts with the PNS to control a function in the body.<\/li>\r\n \t
- For each of the following types of information, identify whether the neuron carrying it is sensory or motor, and whether it is most likely in the somatic or autonomic nervous system:\r\n
\r\n \t- Visual information<\/li>\r\n \t
- Blood pressure information<\/li>\r\n \t
- Information that causes muscle contraction in digestive organs after eating<\/li>\r\n \t
- Information that causes muscle contraction in skeletal muscles based on the person\u2019s decision to make a movement<\/li>\r\n<\/ol>\r\n<\/li>\r\n \t
- [h5p id=\"564\"]<\/li>\r\n<\/ol>\r\n<\/div>\r\n<\/div>\r\n
\r\n8.6 Explore More<\/span><\/h1>\r\n<\/header>\r\n\r\n\r\nhttps:\/\/www.youtube.com\/watch?v=ySIDMU2cy0Y&feature=emb_logo\r\nPhantom Limbs Explained, Plethrons, 2015.<\/p>\r\nhttps:\/\/www.youtube.com\/watch?time_continue=1&v=73yo5nJne6c&feature=emb_logo\r\n
Why Do Hot Peppers Cause Pain? Reactions, 2015.<\/p>\r\n\r\n<\/div>\r\n<\/div>\r\n
Attributions<\/h2>\r\nFigure 8.6.1<\/strong>\r\n\r\nKid\u2019s piant duet<\/a> by\u00a0PJMixer<\/a> on Flickr<\/a> is used under a CC BY-NC-ND 2.0<\/a>\u00a0(https:\/\/creativecommons.org\/licenses\/by-nc-nd\/2.0\/) license.\r\n\r\nFigure 8.6.2<\/strong>\r\n\r\nNervous_system_diagram<\/a> by \u00a4~Persian Poet Gal<\/span><\/span><\/a>\u00a0 on Wikimedia Commons is released into the public domain<\/a> (https:\/\/en.wikipedia.org\/wiki\/Public_domain).\r\n\r\n\r\nFigure 8.6.3<\/strong>\r\n\r\nAfferent_and_efferent_neurons_en.svg<\/a> by Helixitta<\/a> on Wikimedia Commons is used under a CC BY-SA 4.0 <\/a>\u00a0 (https:\/\/creativecommons.org\/licenses\/by-sa\/4.0) license.\r\n\r\nFigure 8.6.4<\/strong>\r\n\r\nAutonomic and Somatic Nervous System<\/a> by Christinelmiller<\/a> on Wikimedia Commons is used under a CC BY-SA 4.0<\/a> (https:\/\/creativecommons.org\/licenses\/by-sa\/4.0) license.\r\n\r\nFigure 8.6.5<\/strong>\r\n\r\nDermatoms.svg<\/a> by Ralf Stephan (mailto:ralf@ark.in-berlin.de) on Wikimedia Commons is released into the public domain<\/a> (https:\/\/en.wikipedia.org\/wiki\/Public_domain).\r\n\r\nFigure 8.6.6<\/strong>\r\n\r\nThe_Autonomic_Nervous_System<\/a> by Geo-Science-International<\/a> on Wikimedia Commons is used and adapted by Christine Miller under a\u00a0CC0 1.0<\/a> Universal\r\nPublic Domain Dedication license (https:\/\/creativecommons.org\/publicdomain\/zero\/1.0\/).\r\nReferences<\/h2>\r\n
Erin Klassen. (2015, December 15). Triangle breathing, 1 minute. YouTube. https:\/\/www.youtube.com\/watch?v=u9Q8D6n-3qw&feature=youtu.be<\/p>\r\n
Jessica Schaffer Nervous System RESET. (2015, January 15). TRE\u00ae : Tension and trauma releasing exercises, an Introduction with Jessica Schaffer. YouTube. https:\/\/www.youtube.com\/watch?v=67R974D8swM&feature=youtu.be<\/p>\r\n
Mayo Clinic Staff. (n.d.). Charcot-Marie-Tooth disease [online article]. MayoClinic.org. https:\/\/www.mayoclinic.org\/diseases-conditions\/charcot-marie-tooth-disease\/symptoms-causes\/syc-20350517<\/p>\r\n
Mayo Clinic Staff. (n.d.). Diabetes [online article]. MayoClinic.org. https:\/\/www.mayoclinic.org\/diseases-conditions\/diabetes\/symptoms-causes\/syc-20371444<\/p>\r\n
Mayo Clinic Staff. (n.d.). Guillain-Barre syndrome [online article]. MayoClinic.org. https:\/\/www.mayoclinic.org\/diseases-conditions\/guillain-barre-syndrome\/symptoms-causes\/syc-20362793<\/p>\r\n
Mayo Clinic Staff. (n.d.). Shingles [online article]. MayoClinic.org. https:\/\/www.mayoclinic.org\/diseases-conditions\/shingles\/symptoms-causes\/syc-20353054<\/p>\r\n
Mayo Clinic Staff. (n.d.). Stroke [online article]. MayoClinic.org. https:\/\/www.mayoclinic.org\/diseases-conditions\/stroke\/symptoms-causes\/syc-20350113<\/p>\r\n
Palouse Mindfulness. (2017, March 25).\u00a0 Mindfulness-based stress reduction (UMass Medical School, Center for Mindfulness), YouTube. https:\/\/www.youtube.com\/watch?v=0TA7P-iCCcY&feature=youtu.be<\/p>\r\n
Plethrons, (2015, March 23). Phantom limbs explained. YouTube. https:\/\/www.youtube.com\/watch?v=ySIDMU2cy0Y&feature=youtu.be<\/p>\r\n
Reactions. (2015, December 1). Why do hot peppers cause pain? YouTube. https:\/\/www.youtube.com\/watch?v=73yo5nJne6c&feature=youtu.be<\/p>\r\n \r\n\r\n \r\n\r\n ","rendered":"
<\/p>\nFigure 8.6.1 A duet with the peripheral nervous system.\u00a0<\/em><\/figcaption><\/figure>\nOne Piano, Four Hands<\/h1>\n
Did you ever see two people play the same piano? How do they coordinate all the movements of their own fingers \u2014 let alone synchronize them with those of their partner? The peripheral nervous system plays an important part in this challenge.<\/p>\n
\nWhat Is the Peripheral Nervous System?<\/h1>\n<\/div>\n
The\u00a0peripheral nervous system<\/a> (PNS)<\/strong>\u00a0consists of all the nervous tissue that lies outside of the\u00a0central nervous system<\/a>\u00a0(CNS). The main function of the PNS is to connect the CNS to the rest of the organism. It serves as a\u00a0communication\u00a0relay, going back and forth between the CNS and\u00a0muscles, organs, and glands throughout the body.<\/p>\nFigure 8.6.2 The nerves of the peripheral nervous system are shown in blue in this diagram.<\/em><\/figcaption><\/figure>\n<\/div>\n\nTissues of the Peripheral Nervous System<\/h1>\n<\/div>\n
The PNS is mostly made up of cable-like bundles of axons called\u00a0nerves<\/a><\/strong>,\u00a0as well as\u00a0clusters of neuronal cell bodies called\u00a0ganglia<\/a><\/strong>\u00a0(singular,\u00a0ganglion<\/a><\/strong>). Nerves are generally classified\u00a0as sensory, motor, or mixed nerves\u00a0based on\u00a0the direction in which they carry\u00a0nerve impulses.<\/p>\n\n- Sensory nerves<\/strong>\u00a0transmit information from sensory receptors in the body to the CNS. Sensory nerves are also called afferent nerves. You can see an example in the figure\u00a0below.<\/li>\n
- Motor nerves<\/a><\/strong>\u00a0transmit information from the CNS to\u00a0muscles, organs, and glands. Motor nerves are also called efferent nerves. You can see one in the figure\u00a0below.<\/li>\n
- Mixed nerves<\/a><\/strong>\u00a0contain both sensory and motor neurons, so they can transmit information in both directions. They have both afferent and efferent functions.<\/li>\n<\/ul>\n
<\/p>\n
\nFigure 8.6.3 In this diagram, each nerve is depicted as a single neuron for simplicity. This afferent neuron sends nerve impulses from sensory receptors in the skin to the CNS. The efferent neuron is a motor neuron that sends nerve impulses from the CNS to a muscle. The cell body of the afferent neuron is located in a ganglion (not pictured), while the cell body of the motor neuron is located in the spinal cord.<\/em><\/figcaption><\/figure>\n<\/div>\n\nDivisions of the Peripheral Nervous System<\/h1>\n<\/div>\n
The PNS is divided into two major systems, called the autonomic nervous system<\/a> and the somatic nervous system<\/a>. In the diagram\u00a0below, the autonomic system is shown on the left, and the somatic system on the right. Both systems of the PNS interact with the CNS and include sensory and motor neurons, but they use different\u00a0circuits\u00a0of nerves and ganglia.<\/p>\nFigure 8.6.4 The two major divisions of the PNS are the autonomic and sensory nervous systems.<\/em><\/figcaption><\/figure>\nSomatic Nervous System<\/h2>\n
The\u00a0somatic nervous system<\/a><\/strong>\u00a0primarily\u00a0senses\u00a0the external environment and controls voluntary activities about which decisions and commands come from the cerebral cortex of the brain. When you feel too warm, for example, you decide to turn on the air conditioner. As you walk across the room to the thermostat, you are using your somatic nervous system. In general, the somatic nervous system is responsible for all of your\u00a0conscious<\/em>\u00a0perceptions of the outside world, as well as all of the voluntary motor activities you perform in response. Whether it\u2019s playing a piano, driving a car, or playing basketball, you can thank your somatic nervous system for making it possible.<\/p>\nSomatic sensory and motor information is transmitted through\u00a012 pairs of cranial nerves and 31 pairs of spinal nerves. Cranial nerves are in the head and neck and connect directly to the brain. Sensory components of cranial nerves\u00a0transmit information about\u00a0smells, tastes, light, sounds, and body position. Motor components of cranial nerves control\u00a0skeletal muscles\u00a0of the face, tongue, eyeballs, throat, head, and shoulders. Motor components of cranial nerves also control the salivary glands and swallowing. Four of the 12 cranial nerves participate in both sensory and motor functions as mixed nerves, having both sensory and motor neurons.<\/p>\n
Spinal nerves emanate from the spinal column between vertebrae. All of the spinal nerves are mixed nerves, containing both sensory and motor neurons. The areas of skin innervated by the 31 pairs of spinal nerves are shown in the figure\u00a0below. These include sensory nerves in the skin that sense pressure,\u00a0temperature, vibrations, and pain. Other sensory nerves are in the\u00a0muscles, and they sense stretching and tension. Spinal nerves also include motor nerves that stimulate\u00a0skeletal muscles\u00a0to contract, allowing for voluntary body movements.<\/p>\nFigure 8.6.5 This drawing shows the areas of the skin innervated by sensory spinal nerves of the somatic nervous system. The left half of the figure shows the nerves in the front of the body, and the right half shows the nerves in the back of the body. The area that each spinal nerve innervates is shown in a different colour.<\/em><\/figcaption><\/figure>\nAutonomic Nervous System<\/h2>\n
The\u00a0autonomic nervous system<\/a><\/strong>\u00a0primarily\u00a0senses\u00a0the internal environment and controls involuntary activities. It is responsible for monitoring conditions in the internal environment and bringing about appropriate changes in them. In general, the\u00a0autonomic\u00a0nervous system is responsible for all the activities that go on inside your body\u00a0without<\/em>\u00a0your conscious awareness or voluntary participation.<\/p>\nStructurally, the autonomic nervous system consists of sensory and motor nerves that run between the CNS (especially the hypothalamus in the brain), internal organs (such as the\u00a0heart, lungs, and digestive organs), and glands (such as the\u00a0pancreas\u00a0and sweat glands). Sensory neurons<\/a> in the autonomic system detect internal body conditions and send messages to the brain. Motor nerves in the autonomic system affect appropriate responses by controlling contractions of smooth or cardiac muscle, or glandular tissue. For example, when sensory nerves of the autonomic system detect a rise in body\u00a0temperature, motor nerves signal smooth muscles in\u00a0blood vessels\u00a0near the body surface to undergo vasodilation, and the sweat glands in the skin to secrete more sweat to cool the body.<\/p>\nThe autonomic nervous system, in turn, has three subdivisions: the sympathetic division<\/a>, parasympathetic division<\/a>, and enteric division<\/a>. The first two subdivisions of the autonomic system are summarized in the figure\u00a0below. Both affect the same organs and glands, but they generally do so in opposite ways.<\/p>\n\n- The\u00a0sympathetic division<\/strong>\u00a0controls the fight-or-flight response. Changes occur in organs and glands throughout the body that prepare the body to fight or flee in response to a perceived danger. For example, the\u00a0heart\u00a0rate speeds up, air passages in the lungs become wider, more\u00a0blood\u00a0flows to the\u00a0skeletal muscles, and the\u00a0digestive system temporarily shuts down.<\/li>\n
- The\u00a0parasympathetic division<\/strong>\u00a0returns the body to normal after the fight-or-flight response has occurred. For example, it slows down the\u00a0heart\u00a0rate, narrows air passages in the lungs, reduces\u00a0blood\u00a0flow to the skeletal muscles, and stimulates the\u00a0digestive system\u00a0to start working again. The parasympathetic division also maintains internal\u00a0homeostasis\u00a0of the body at other times.<\/li>\n
- The\u00a0enteric division<\/strong> is made up of nerve fibres that supply the organs of the digestive system. This division allows for the local control of many digestive functions.<\/li>\n<\/ul>\n
Figure 8.6.6 This diagram summarizes the structures and functions controlled by the parasympathetic and sympathetic divisions of the autonomic nervous system.<\/em><\/figcaption><\/figure>\nDisorders of the Peripheral Nervous System<\/span><\/p>\nUnlike the CNS \u2014 which is protected by\u00a0bone<\/a>s, meninges<\/a>, and cerebrospinal fluid<\/a> \u2014 the PNS has no such protections. The PNS also has no blood-brain barrier to protect it from toxins and pathogens in the\u00a0blood. Therefore, the PNS is more subject to injury and disease than is the CNS. Causes of nerve injury include\u00a0diabetes<\/a>,\u00a0infectious diseases\u00a0(such as shingles<\/a>), and poisoning by toxins (such as heavy metals). PNS disorders often have symptoms\u00a0like\u00a0loss of feeling, tingling, burning sensations, or muscle weakness. If a traumatic injury results in a nerve being transected (cut all the way through), it may regenerate, but this is a very slow process and may take many months.<\/p>\nTwo other diseases of the PNS are Guillain-Barre syndrome and Charcot-Marie-Tooth disease.<\/p>\n
\n- Guillain-Barre syndrome<\/a> is a rare disease in which the immune system attacks nerves of the PNS, leading to muscle weakness and even paralysis. The exact cause of Guillain-Barre syndrome is unknown, but it often occurs after a viral or bacterial infection. There is no known cure for the syndrome, but most people eventually make a full recovery. Recovery can be slow, however, lasting anywhere from several weeks to several years.<\/li>\n
- Charcot-Marie-Tooth disease<\/a> is a hereditary disorder of the nerves, and one of the most common inherited neurological disorders. It affects predominantly the nerves in the feet and legs,\u00a0and often\u00a0in the hands and arms, as well. The disease is characterized by loss of muscle tissue and sense of touch. It is presently incurable.<\/li>\n<\/ul>\n\n
Feature: My\u00a0Human Body<\/h1>\n<\/div>\n
The autonomic nervous system is considered to be involuntary because it doesn’t require conscious input. However, it\u00a0is<\/em>\u00a0possible to exert some voluntary control over it. People who practice yoga or other so-called mind-body techniques, for example,\u00a0can\u00a0reduce their heart rate and certain other autonomic functions. Slowing down these otherwise involuntary responses is a good way to relieve stress and reduce the wear-and-tear that stress can place on the body. Such techniques may also be useful for controlling post-traumatic stress disorder and chronic pain. Three types of integrative practices for these purposes\u00a0are\u00a0breathing exercises, body-based tension modulation exercises, and mindfulness techniques.<\/p>\nBreathing exercises can help control the rapid, shallow breathing that often occurs when you are anxious or under stress. These exercises can be learned quickly, and they provide immediate feelings of relief. Specific breathing exercises include paced breath, diaphragmatic breathing, and Breathe2Relax or Chill Zone on MindShift\u2122 CBT, which are downloadable breathing practice mobile applications, or “Apps”. Try syncing your breathing with Eric Klassen’s “Triangle breathing, 1 minute” video:<\/p>\n
https:\/\/www.youtube.com\/watch?v=u9Q8D6n-3qw<\/p>\n
Triangle breathing, 1 minute, Erin Klassen, 2015.<\/p>\n
Body-based tension modulation exercises include yoga postures (also known as \u201casanas\u201d) and tension manipulation exercises. The latter include the Trauma\/Tension Release\u00a0Exercise\u00a0(TRE) and the Trauma Resiliency Model (TRM). Watch this video for a brief \u2014 but informative \u2014 introduction to the TRE program:<\/p>\n
https:\/\/www.youtube.com\/watch?v=67R974D8swM&feature=youtu.be<\/p>\n
TRE\u00ae : Tension and Trauma Releasing Exercises, an Introduction with Jessica Schaffer, Jessica Schaffer Nervous System RESET, 2015.<\/p>\n
Mindfulness techniques have been shown to reduce symptoms of depression, as well as those of anxiety and stress. They have also been shown to be useful for pain management and performance enhancement. Specific mindfulness programs include Mindfulness Based Stress Reduction (MBSR) and Mindfulness Mind-Fitness Training (MMFT). You can learn more about MBSR by watching the video below.<\/p>\n
Figure 8.6.6 This diagram summarizes the structures and functions controlled by the parasympathetic and sympathetic divisions of the autonomic nervous system.<\/em>[\/caption]\r\n\r\nDisorders of the Peripheral Nervous System<\/span>\r\n\r\nUnlike the CNS \u2014 which is protected by\u00a0[pb_glossary id=\"5913\"]bone[\/pb_glossary]s, [pb_glossary id=\"2929\"]meninges[\/pb_glossary], and [pb_glossary id=\"5939\"]cerebrospinal fluid[\/pb_glossary] \u2014 the PNS has no such protections. The PNS also has no blood-brain barrier to protect it from toxins and pathogens in the\u00a0blood. Therefore, the PNS is more subject to injury and disease than is the CNS. Causes of nerve injury include\u00a0diabetes<\/a>,\u00a0infectious diseases\u00a0(such as shingles<\/a>), and poisoning by toxins (such as heavy metals). PNS disorders often have symptoms\u00a0like\u00a0loss of feeling, tingling, burning sensations, or muscle weakness. If a traumatic injury results in a nerve being transected (cut all the way through), it may regenerate, but this is a very slow process and may take many months.\r\n\r\nTwo other diseases of the PNS are Guillain-Barre syndrome and Charcot-Marie-Tooth disease.\r\n- \r\n \t
- Guillain-Barre syndrome<\/a> is a rare disease in which the immune system attacks nerves of the PNS, leading to muscle weakness and even paralysis. The exact cause of Guillain-Barre syndrome is unknown, but it often occurs after a viral or bacterial infection. There is no known cure for the syndrome, but most people eventually make a full recovery. Recovery can be slow, however, lasting anywhere from several weeks to several years.<\/li>\r\n \t
- Charcot-Marie-Tooth disease<\/a> is a hereditary disorder of the nerves, and one of the most common inherited neurological disorders. It affects predominantly the nerves in the feet and legs,\u00a0and often\u00a0in the hands and arms, as well. The disease is characterized by loss of muscle tissue and sense of touch. It is presently incurable.<\/li>\r\n<\/ul>\r\n
\r\nFeature: My\u00a0Human Body<\/h1>\r\n<\/div>\r\nThe autonomic nervous system is considered to be involuntary because it doesn't require conscious input. However, it\u00a0is<\/em>\u00a0possible to exert some voluntary control over it. People who practice yoga or other so-called mind-body techniques, for example,\u00a0can\u00a0reduce their heart rate and certain other autonomic functions. Slowing down these otherwise involuntary responses is a good way to relieve stress and reduce the wear-and-tear that stress can place on the body. Such techniques may also be useful for controlling post-traumatic stress disorder and chronic pain. Three types of integrative practices for these purposes\u00a0are\u00a0breathing exercises, body-based tension modulation exercises, and mindfulness techniques.\r\n\r\nBreathing exercises can help control the rapid, shallow breathing that often occurs when you are anxious or under stress. These exercises can be learned quickly, and they provide immediate feelings of relief. Specific breathing exercises include paced breath, diaphragmatic breathing, and Breathe2Relax or Chill Zone on MindShift\u2122 CBT, which are downloadable breathing practice mobile applications, or \"Apps\". Try syncing your breathing with Eric Klassen's \"Triangle breathing, 1 minute\" video:\r\n\r\nhttps:\/\/www.youtube.com\/watch?v=u9Q8D6n-3qw\r\n
Triangle breathing, 1 minute, Erin Klassen, 2015.<\/p>\r\nBody-based tension modulation exercises include yoga postures (also known as \u201casanas\u201d) and tension manipulation exercises. The latter include the Trauma\/Tension Release\u00a0Exercise\u00a0(TRE) and the Trauma Resiliency Model (TRM). Watch this video for a brief \u2014 but informative \u2014 introduction to the TRE program:\r\n\r\nhttps:\/\/www.youtube.com\/watch?v=67R974D8swM&feature=youtu.be\r\n
TRE\u00ae : Tension and Trauma Releasing Exercises, an Introduction with Jessica Schaffer, Jessica Schaffer Nervous System RESET, 2015.<\/p>\r\nMindfulness techniques have been shown to reduce symptoms of depression, as well as those of anxiety and stress. They have also been shown to be useful for pain management and performance enhancement. Specific mindfulness programs include Mindfulness Based Stress Reduction (MBSR) and Mindfulness Mind-Fitness Training (MMFT). You can learn more about MBSR by watching the video below.\r\n\r\nhttps:\/\/www.youtube.com\/watch?v=0TA7P-iCCcY&feature=youtu.be\r\n
Mindfulness-Based Stress Reduction (UMass Medical School, Center for Mindfulness), Palouse Mindfulness, 2017.<\/p>\r\n\r\n
\r\n 8.6 Summary<\/span><\/h1>\r\n<\/header>\r\n
\r\n- \r\n \t
- The [pb_glossary id=\"3009\"]peripheral nervous system[\/pb_glossary] (PNS) consists of all the nervous tissue that lies outside the\u00a0[pb_glossary id=\"5933\"]central nervous system[\/pb_glossary] (CNS). Its main function is to connect the CNS to the rest of the organism.<\/li>\r\n \t
- The PNS is made up of [pb_glossary id=\"3011\"]nerves[\/pb_glossary] and [pb_glossary id=\"6027\"]ganglia[\/pb_glossary]. Nerves are bundles of [pb_glossary id=\"5901\"]axons[\/pb_glossary], and ganglia are groups of [pb_glossary id=\"5931\"]cell bodies[\/pb_glossary]. Nerves are classified as sensory, motor, or a mix of the two.<\/li>\r\n \t
- The PNS is divided into the [pb_glossary id=\"3014\"]somatic[\/pb_glossary] and [pb_glossary id=\"5899\"]autonomic nervous systems[\/pb_glossary]. The somatic system controls [pb_glossary id=\"3004\"]voluntary[\/pb_glossary] activities, whereas the autonomic system controls [pb_glossary id=\"3005\"]involuntary[\/pb_glossary] activities.<\/li>\r\n \t
- The autonomic nervous system is further divided into [pb_glossary id=\"3015\"]sympathetic[\/pb_glossary], [pb_glossary id=\"3016\"]parasympathetic[\/pb_glossary], and [pb_glossary id=\"5987\"]enteric divisions[\/pb_glossary]. The sympathetic division controls [pb_glossary id=\"6013\"]fight-or-flight responses[\/pb_glossary]\u00a0during emergencies, the parasympathetic system controls routine body functions the rest of the time, and the enteric division provides local control over the [pb_glossary id=\"5969\"]digestive system[\/pb_glossary].<\/li>\r\n \t
- The PNS is not as well protected physically or chemically as the CNS, so it is more prone to injury and disease. PNS problems include injury from\u00a0diabetes, shingles, and heavy metal poisoning. Two disorders of the PNS are Guillain-Barre syndrome and Charcot-Marie-Tooth disease.<\/li>\r\n<\/ul>\r\n<\/div>\r\n<\/div>\r\n
\r\n 8.6 Review Questions<\/span><\/h1>\r\n<\/header>\r\n
\r\n- \r\n \t
- Describe the general structure of the peripheral nervous system. State its primary function.<\/li>\r\n \t
- What are ganglia?<\/li>\r\n \t
- Identify three types of nerves based on the direction in which they carry\u00a0nerve impulses.<\/li>\r\n \t
- Outline all of the divisions of the peripheral nervous system.<\/li>\r\n \t
- Compare and contrast the somatic and autonomic nervous systems.<\/li>\r\n \t
- When and how does the sympathetic division of the autonomic nervous system affect the body?<\/li>\r\n \t
- What is the function of the parasympathetic division of the autonomic nervous system?\u00a0Specifically, how does it affect the body?<\/li>\r\n \t
- Name and describe two peripheral nervous system disorders.<\/li>\r\n \t
- Give one example of how the CNS interacts with the PNS to control a function in the body.<\/li>\r\n \t
- For each of the following types of information, identify whether the neuron carrying it is sensory or motor, and whether it is most likely in the somatic or autonomic nervous system:\r\n
- \r\n \t
- Visual information<\/li>\r\n \t
- Blood pressure information<\/li>\r\n \t
- Information that causes muscle contraction in digestive organs after eating<\/li>\r\n \t
- Information that causes muscle contraction in skeletal muscles based on the person\u2019s decision to make a movement<\/li>\r\n<\/ol>\r\n<\/li>\r\n \t
- [h5p id=\"564\"]<\/li>\r\n<\/ol>\r\n<\/div>\r\n<\/div>\r\n
\r\n 8.6 Explore More<\/span><\/h1>\r\n<\/header>\r\n
\r\n\r\nhttps:\/\/www.youtube.com\/watch?v=ySIDMU2cy0Y&feature=emb_logo\r\nPhantom Limbs Explained, Plethrons, 2015.<\/p>\r\nhttps:\/\/www.youtube.com\/watch?time_continue=1&v=73yo5nJne6c&feature=emb_logo\r\n
Why Do Hot Peppers Cause Pain? Reactions, 2015.<\/p>\r\n\r\n<\/div>\r\n<\/div>\r\n
Attributions<\/h2>\r\nFigure 8.6.1<\/strong>\r\n\r\nKid\u2019s piant duet<\/a> by\u00a0PJMixer<\/a> on Flickr<\/a> is used under a CC BY-NC-ND 2.0<\/a>\u00a0(https:\/\/creativecommons.org\/licenses\/by-nc-nd\/2.0\/) license.\r\n\r\nFigure 8.6.2<\/strong>\r\n\r\nNervous_system_diagram<\/a> by \u00a4~Persian Poet Gal<\/span><\/span><\/a>\u00a0 on Wikimedia Commons is released into the public domain<\/a> (https:\/\/en.wikipedia.org\/wiki\/Public_domain).\r\n\r\n\r\nFigure 8.6.3<\/strong>\r\n\r\nAfferent_and_efferent_neurons_en.svg<\/a> by Helixitta<\/a> on Wikimedia Commons is used under a CC BY-SA 4.0 <\/a>\u00a0 (https:\/\/creativecommons.org\/licenses\/by-sa\/4.0) license.\r\n\r\nFigure 8.6.4<\/strong>\r\n\r\nAutonomic and Somatic Nervous System<\/a> by Christinelmiller<\/a> on Wikimedia Commons is used under a CC BY-SA 4.0<\/a> (https:\/\/creativecommons.org\/licenses\/by-sa\/4.0) license.\r\n\r\nFigure 8.6.5<\/strong>\r\n\r\nDermatoms.svg<\/a> by Ralf Stephan (mailto:ralf@ark.in-berlin.de) on Wikimedia Commons is released into the public domain<\/a> (https:\/\/en.wikipedia.org\/wiki\/Public_domain).\r\n\r\nFigure 8.6.6<\/strong>\r\n\r\nThe_Autonomic_Nervous_System<\/a> by Geo-Science-International<\/a> on Wikimedia Commons is used and adapted by Christine Miller under a\u00a0CC0 1.0<\/a> Universal\r\nPublic Domain Dedication license (https:\/\/creativecommons.org\/publicdomain\/zero\/1.0\/).\r\n
References<\/h2>\r\n
Erin Klassen. (2015, December 15). Triangle breathing, 1 minute. YouTube. https:\/\/www.youtube.com\/watch?v=u9Q8D6n-3qw&feature=youtu.be<\/p>\r\n
Jessica Schaffer Nervous System RESET. (2015, January 15). TRE\u00ae : Tension and trauma releasing exercises, an Introduction with Jessica Schaffer. YouTube. https:\/\/www.youtube.com\/watch?v=67R974D8swM&feature=youtu.be<\/p>\r\n
Mayo Clinic Staff. (n.d.). Charcot-Marie-Tooth disease [online article]. MayoClinic.org. https:\/\/www.mayoclinic.org\/diseases-conditions\/charcot-marie-tooth-disease\/symptoms-causes\/syc-20350517<\/p>\r\n
Mayo Clinic Staff. (n.d.). Diabetes [online article]. MayoClinic.org. https:\/\/www.mayoclinic.org\/diseases-conditions\/diabetes\/symptoms-causes\/syc-20371444<\/p>\r\n
Mayo Clinic Staff. (n.d.). Guillain-Barre syndrome [online article]. MayoClinic.org. https:\/\/www.mayoclinic.org\/diseases-conditions\/guillain-barre-syndrome\/symptoms-causes\/syc-20362793<\/p>\r\n
Mayo Clinic Staff. (n.d.). Shingles [online article]. MayoClinic.org. https:\/\/www.mayoclinic.org\/diseases-conditions\/shingles\/symptoms-causes\/syc-20353054<\/p>\r\n
Mayo Clinic Staff. (n.d.). Stroke [online article]. MayoClinic.org. https:\/\/www.mayoclinic.org\/diseases-conditions\/stroke\/symptoms-causes\/syc-20350113<\/p>\r\n
Palouse Mindfulness. (2017, March 25).\u00a0 Mindfulness-based stress reduction (UMass Medical School, Center for Mindfulness), YouTube. https:\/\/www.youtube.com\/watch?v=0TA7P-iCCcY&feature=youtu.be<\/p>\r\n
Plethrons, (2015, March 23). Phantom limbs explained. YouTube. https:\/\/www.youtube.com\/watch?v=ySIDMU2cy0Y&feature=youtu.be<\/p>\r\n
Reactions. (2015, December 1). Why do hot peppers cause pain? YouTube. https:\/\/www.youtube.com\/watch?v=73yo5nJne6c&feature=youtu.be<\/p>\r\n \r\n\r\n \r\n\r\n ","rendered":"
<\/p>\n
Figure 8.6.1 A duet with the peripheral nervous system.\u00a0<\/em><\/figcaption><\/figure>\n One Piano, Four Hands<\/h1>\n
Did you ever see two people play the same piano? How do they coordinate all the movements of their own fingers \u2014 let alone synchronize them with those of their partner? The peripheral nervous system plays an important part in this challenge.<\/p>\n
\nWhat Is the Peripheral Nervous System?<\/h1>\n<\/div>\n
The\u00a0peripheral nervous system<\/a> (PNS)<\/strong>\u00a0consists of all the nervous tissue that lies outside of the\u00a0central nervous system<\/a>\u00a0(CNS). The main function of the PNS is to connect the CNS to the rest of the organism. It serves as a\u00a0communication\u00a0relay, going back and forth between the CNS and\u00a0muscles, organs, and glands throughout the body.<\/p>\n
Figure 8.6.2 The nerves of the peripheral nervous system are shown in blue in this diagram.<\/em><\/figcaption><\/figure>\n <\/div>\n\nTissues of the Peripheral Nervous System<\/h1>\n<\/div>\n
The PNS is mostly made up of cable-like bundles of axons called\u00a0nerves<\/a><\/strong>,\u00a0as well as\u00a0clusters of neuronal cell bodies called\u00a0ganglia<\/a><\/strong>\u00a0(singular,\u00a0ganglion<\/a><\/strong>). Nerves are generally classified\u00a0as sensory, motor, or mixed nerves\u00a0based on\u00a0the direction in which they carry\u00a0nerve impulses.<\/p>\n
- \n
- Sensory nerves<\/strong>\u00a0transmit information from sensory receptors in the body to the CNS. Sensory nerves are also called afferent nerves. You can see an example in the figure\u00a0below.<\/li>\n
- Motor nerves<\/a><\/strong>\u00a0transmit information from the CNS to\u00a0muscles, organs, and glands. Motor nerves are also called efferent nerves. You can see one in the figure\u00a0below.<\/li>\n
- Mixed nerves<\/a><\/strong>\u00a0contain both sensory and motor neurons, so they can transmit information in both directions. They have both afferent and efferent functions.<\/li>\n<\/ul>\n
<\/p>\n
\nFigure 8.6.3 In this diagram, each nerve is depicted as a single neuron for simplicity. This afferent neuron sends nerve impulses from sensory receptors in the skin to the CNS. The efferent neuron is a motor neuron that sends nerve impulses from the CNS to a muscle. The cell body of the afferent neuron is located in a ganglion (not pictured), while the cell body of the motor neuron is located in the spinal cord.<\/em><\/figcaption><\/figure>\n<\/div>\n \nDivisions of the Peripheral Nervous System<\/h1>\n<\/div>\n
The PNS is divided into two major systems, called the autonomic nervous system<\/a> and the somatic nervous system<\/a>. In the diagram\u00a0below, the autonomic system is shown on the left, and the somatic system on the right. Both systems of the PNS interact with the CNS and include sensory and motor neurons, but they use different\u00a0circuits\u00a0of nerves and ganglia.<\/p>\n
Figure 8.6.4 The two major divisions of the PNS are the autonomic and sensory nervous systems.<\/em><\/figcaption><\/figure>\n Somatic Nervous System<\/h2>\n
The\u00a0somatic nervous system<\/a><\/strong>\u00a0primarily\u00a0senses\u00a0the external environment and controls voluntary activities about which decisions and commands come from the cerebral cortex of the brain. When you feel too warm, for example, you decide to turn on the air conditioner. As you walk across the room to the thermostat, you are using your somatic nervous system. In general, the somatic nervous system is responsible for all of your\u00a0conscious<\/em>\u00a0perceptions of the outside world, as well as all of the voluntary motor activities you perform in response. Whether it\u2019s playing a piano, driving a car, or playing basketball, you can thank your somatic nervous system for making it possible.<\/p>\n
Somatic sensory and motor information is transmitted through\u00a012 pairs of cranial nerves and 31 pairs of spinal nerves. Cranial nerves are in the head and neck and connect directly to the brain. Sensory components of cranial nerves\u00a0transmit information about\u00a0smells, tastes, light, sounds, and body position. Motor components of cranial nerves control\u00a0skeletal muscles\u00a0of the face, tongue, eyeballs, throat, head, and shoulders. Motor components of cranial nerves also control the salivary glands and swallowing. Four of the 12 cranial nerves participate in both sensory and motor functions as mixed nerves, having both sensory and motor neurons.<\/p>\n
Spinal nerves emanate from the spinal column between vertebrae. All of the spinal nerves are mixed nerves, containing both sensory and motor neurons. The areas of skin innervated by the 31 pairs of spinal nerves are shown in the figure\u00a0below. These include sensory nerves in the skin that sense pressure,\u00a0temperature, vibrations, and pain. Other sensory nerves are in the\u00a0muscles, and they sense stretching and tension. Spinal nerves also include motor nerves that stimulate\u00a0skeletal muscles\u00a0to contract, allowing for voluntary body movements.<\/p>\n
Figure 8.6.5 This drawing shows the areas of the skin innervated by sensory spinal nerves of the somatic nervous system. The left half of the figure shows the nerves in the front of the body, and the right half shows the nerves in the back of the body. The area that each spinal nerve innervates is shown in a different colour.<\/em><\/figcaption><\/figure>\n Autonomic Nervous System<\/h2>\n
The\u00a0autonomic nervous system<\/a><\/strong>\u00a0primarily\u00a0senses\u00a0the internal environment and controls involuntary activities. It is responsible for monitoring conditions in the internal environment and bringing about appropriate changes in them. In general, the\u00a0autonomic\u00a0nervous system is responsible for all the activities that go on inside your body\u00a0without<\/em>\u00a0your conscious awareness or voluntary participation.<\/p>\n
Structurally, the autonomic nervous system consists of sensory and motor nerves that run between the CNS (especially the hypothalamus in the brain), internal organs (such as the\u00a0heart, lungs, and digestive organs), and glands (such as the\u00a0pancreas\u00a0and sweat glands). Sensory neurons<\/a> in the autonomic system detect internal body conditions and send messages to the brain. Motor nerves in the autonomic system affect appropriate responses by controlling contractions of smooth or cardiac muscle, or glandular tissue. For example, when sensory nerves of the autonomic system detect a rise in body\u00a0temperature, motor nerves signal smooth muscles in\u00a0blood vessels\u00a0near the body surface to undergo vasodilation, and the sweat glands in the skin to secrete more sweat to cool the body.<\/p>\n
The autonomic nervous system, in turn, has three subdivisions: the sympathetic division<\/a>, parasympathetic division<\/a>, and enteric division<\/a>. The first two subdivisions of the autonomic system are summarized in the figure\u00a0below. Both affect the same organs and glands, but they generally do so in opposite ways.<\/p>\n
- \n
- The\u00a0sympathetic division<\/strong>\u00a0controls the fight-or-flight response. Changes occur in organs and glands throughout the body that prepare the body to fight or flee in response to a perceived danger. For example, the\u00a0heart\u00a0rate speeds up, air passages in the lungs become wider, more\u00a0blood\u00a0flows to the\u00a0skeletal muscles, and the\u00a0digestive system temporarily shuts down.<\/li>\n
- The\u00a0parasympathetic division<\/strong>\u00a0returns the body to normal after the fight-or-flight response has occurred. For example, it slows down the\u00a0heart\u00a0rate, narrows air passages in the lungs, reduces\u00a0blood\u00a0flow to the skeletal muscles, and stimulates the\u00a0digestive system\u00a0to start working again. The parasympathetic division also maintains internal\u00a0homeostasis\u00a0of the body at other times.<\/li>\n
- The\u00a0enteric division<\/strong> is made up of nerve fibres that supply the organs of the digestive system. This division allows for the local control of many digestive functions.<\/li>\n<\/ul>\n
Figure 8.6.6 This diagram summarizes the structures and functions controlled by the parasympathetic and sympathetic divisions of the autonomic nervous system.<\/em><\/figcaption><\/figure>\n Disorders of the Peripheral Nervous System<\/span><\/p>\n
Unlike the CNS \u2014 which is protected by\u00a0bone<\/a>s, meninges<\/a>, and cerebrospinal fluid<\/a> \u2014 the PNS has no such protections. The PNS also has no blood-brain barrier to protect it from toxins and pathogens in the\u00a0blood. Therefore, the PNS is more subject to injury and disease than is the CNS. Causes of nerve injury include\u00a0diabetes<\/a>,\u00a0infectious diseases\u00a0(such as shingles<\/a>), and poisoning by toxins (such as heavy metals). PNS disorders often have symptoms\u00a0like\u00a0loss of feeling, tingling, burning sensations, or muscle weakness. If a traumatic injury results in a nerve being transected (cut all the way through), it may regenerate, but this is a very slow process and may take many months.<\/p>\n
Two other diseases of the PNS are Guillain-Barre syndrome and Charcot-Marie-Tooth disease.<\/p>\n
- \n
- Guillain-Barre syndrome<\/a> is a rare disease in which the immune system attacks nerves of the PNS, leading to muscle weakness and even paralysis. The exact cause of Guillain-Barre syndrome is unknown, but it often occurs after a viral or bacterial infection. There is no known cure for the syndrome, but most people eventually make a full recovery. Recovery can be slow, however, lasting anywhere from several weeks to several years.<\/li>\n
- Charcot-Marie-Tooth disease<\/a> is a hereditary disorder of the nerves, and one of the most common inherited neurological disorders. It affects predominantly the nerves in the feet and legs,\u00a0and often\u00a0in the hands and arms, as well. The disease is characterized by loss of muscle tissue and sense of touch. It is presently incurable.<\/li>\n<\/ul>\n
\nFeature: My\u00a0Human Body<\/h1>\n<\/div>\n
The autonomic nervous system is considered to be involuntary because it doesn’t require conscious input. However, it\u00a0is<\/em>\u00a0possible to exert some voluntary control over it. People who practice yoga or other so-called mind-body techniques, for example,\u00a0can\u00a0reduce their heart rate and certain other autonomic functions. Slowing down these otherwise involuntary responses is a good way to relieve stress and reduce the wear-and-tear that stress can place on the body. Such techniques may also be useful for controlling post-traumatic stress disorder and chronic pain. Three types of integrative practices for these purposes\u00a0are\u00a0breathing exercises, body-based tension modulation exercises, and mindfulness techniques.<\/p>\n
Breathing exercises can help control the rapid, shallow breathing that often occurs when you are anxious or under stress. These exercises can be learned quickly, and they provide immediate feelings of relief. Specific breathing exercises include paced breath, diaphragmatic breathing, and Breathe2Relax or Chill Zone on MindShift\u2122 CBT, which are downloadable breathing practice mobile applications, or “Apps”. Try syncing your breathing with Eric Klassen’s “Triangle breathing, 1 minute” video:<\/p>\n
https:\/\/www.youtube.com\/watch?v=u9Q8D6n-3qw<\/p>\n
Triangle breathing, 1 minute, Erin Klassen, 2015.<\/p>\n
Body-based tension modulation exercises include yoga postures (also known as \u201casanas\u201d) and tension manipulation exercises. The latter include the Trauma\/Tension Release\u00a0Exercise\u00a0(TRE) and the Trauma Resiliency Model (TRM). Watch this video for a brief \u2014 but informative \u2014 introduction to the TRE program:<\/p>\n
https:\/\/www.youtube.com\/watch?v=67R974D8swM&feature=youtu.be<\/p>\n
TRE\u00ae : Tension and Trauma Releasing Exercises, an Introduction with Jessica Schaffer, Jessica Schaffer Nervous System RESET, 2015.<\/p>\n
Mindfulness techniques have been shown to reduce symptoms of depression, as well as those of anxiety and stress. They have also been shown to be useful for pain management and performance enhancement. Specific mindfulness programs include Mindfulness Based Stress Reduction (MBSR) and Mindfulness Mind-Fitness Training (MMFT). You can learn more about MBSR by watching the video below.<\/p>\n
- Charcot-Marie-Tooth disease<\/a> is a hereditary disorder of the nerves, and one of the most common inherited neurological disorders. It affects predominantly the nerves in the feet and legs,\u00a0and often\u00a0in the hands and arms, as well. The disease is characterized by loss of muscle tissue and sense of touch. It is presently incurable.<\/li>\n<\/ul>\n
- The\u00a0parasympathetic division<\/strong>\u00a0returns the body to normal after the fight-or-flight response has occurred. For example, it slows down the\u00a0heart\u00a0rate, narrows air passages in the lungs, reduces\u00a0blood\u00a0flow to the skeletal muscles, and stimulates the\u00a0digestive system\u00a0to start working again. The parasympathetic division also maintains internal\u00a0homeostasis\u00a0of the body at other times.<\/li>\n
- Motor nerves<\/a><\/strong>\u00a0transmit information from the CNS to\u00a0muscles, organs, and glands. Motor nerves are also called efferent nerves. You can see one in the figure\u00a0below.<\/li>\n
- Sensory nerves<\/strong>\u00a0transmit information from sensory receptors in the body to the CNS. Sensory nerves are also called afferent nerves. You can see an example in the figure\u00a0below.<\/li>\n
- Charcot-Marie-Tooth disease<\/a> is a hereditary disorder of the nerves, and one of the most common inherited neurological disorders. It affects predominantly the nerves in the feet and legs,\u00a0and often\u00a0in the hands and arms, as well. The disease is characterized by loss of muscle tissue and sense of touch. It is presently incurable.<\/li>\r\n<\/ul>\r\n
![Nervous_system_diagram<\/a> by](\"https:\/\/commons.wikimedia.org\/wiki\/File:Nervous_system_diagram.png\"){kind=link}
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