           Nerve cell (neuron)       Open pop-up dialog box          Close    Nerve cell (neuron)   Nerve cell (neuron) The basic unit of communication in the nervous system is the nerve cell (neuron). Each nerve cell consists of the cell body, which includes the nucleus, a major branching fiber (axon) and numerous smaller branching fibers (dendrites). The myelin sheath is fatty material that covers, insulates and protects nerves of the brain and spinal cord.               Nerve cell (neuron)       Open pop-up dialog box           Nerve cell (neuron)       Open pop-up dialog box  Open pop-up dialog box       Close    Nerve cell (neuron)   Nerve cell (neuron) The basic unit of communication in the nervous system is the nerve cell (neuron). Each nerve cell consists of the cell body, which includes the nucleus, a major branching fiber (axon) and numerous smaller branching fibers (dendrites). The myelin sheath is fatty material that covers, insulates and protects nerves of the brain and spinal cord.          Close    Nerve cell (neuron)   Nerve cell (neuron) The basic unit of communication in the nervous system is the nerve cell (neuron). Each nerve cell consists of the cell body, which includes the nucleus, a major branching fiber (axon) and numerous smaller branching fibers (dendrites). The myelin sheath is fatty material that covers, insulates and protects nerves of the brain and spinal cord.        Close    Nerve cell (neuron)   Nerve cell (neuron) The basic unit of communication in the nervous system is the nerve cell (neuron). Each nerve cell consists of the cell body, which includes the nucleus, a major branching fiber (axon) and numerous smaller branching fibers (dendrites). The myelin sheath is fatty material that covers, insulates and protects nerves of the brain and spinal cord.     Close    Close  Close Nerve cell (neuron)   Nerve cell (neuron) The basic unit of communication in the nervous system is the nerve cell (neuron). Each nerve cell consists of the cell body, which includes the nucleus, a major branching fiber (axon) and numerous smaller branching fibers (dendrites). The myelin sheath is fatty material that covers, insulates and protects nerves of the brain and spinal cord.  Nerve cell (neuron) The basic unit of communication in the nervous system is the nerve cell (neuron). Each nerve cell consists of the cell body, which includes the nucleus, a major branching fiber (axon) and numerous smaller branching fibers (dendrites). The myelin sheath is fatty material that covers, insulates and protects nerves of the brain and spinal cord. The basic unit of communication in the nervous system is the nerve cell (neuron). Each nerve cell consists of the cell body, which includes the nucleus, a major branching fiber (axon) and numerous smaller branching fibers (dendrites). The myelin sheath is fatty material that covers, insulates and protects nerves of the brain and spinal cord. Most people infected with the virus that causes polio, called poliovirus, don't get symptoms. Abortive polio About 5% of people with the poliovirus get a mild version of the disease called abortive poliomyelitis. This leads to flu-like symptoms that last 2 to 3 days. These include:  Fever Headache Muscle aches Sore throat Stomachache Loss of appetite Nausea Vomiting  Nonparalytic polio A more severe form of the disease, called nonparalytic polio, affects about 1% of those infected. While the illness lasts longer than a few days, it doesn't cause paralysis. Besides having more-severe flu-like symptoms, nonparalytic polio symptoms may include:  Neck pain or stiffness Aches or stiffness in the arms or legs Severe headache  A second phase of symptoms may follow, or a person may seem to be getting better for a few days before a second phase starts. These symptoms include:  Stiffness of the spine and neck Decreased reflexes Muscle weakness  Paralytic polio This most serious form of the disease is rare. The disease begins much like nonparalytic polio. But it progresses to more-severe signs and symptoms, including:  Intense pain Extreme sensitivity to touch Tingling or pricking sensations Muscles spasms or twitching Muscles weakness progressing to a limp paralysis  Any combination of limbs may experience paralysis. But paralysis of one leg is most common, followed by paralysis of one arm. Depending on the severity of disease, other signs or symptoms may include:  Paralysis of muscles involved in breathing Difficulty swallowing  Post-polio syndrome Post-polio syndrome is the appearance of new signs or symptoms or the progression of problems. This usually happens decades after having polio. Common signs and symptoms include:  Progressive muscle or joint weakness and pain Fatigue Muscle wasting Breathing or swallowing problems Sleep-related breathing disorders, such as sleep apnea Lowered tolerance of cold temperatures 
           nerve cell (neuron)       open pop-up dialog box          close    nerve cell (neuron)   nerve cell (neuron) basic unit communication nervous system nerve cell (neuron)  nerve cell consists cell body  includes nucleus  major branching fiber (axon) numerous smaller branching fibers (dendrites)  myelin sheath fatty material covers  insulates protects nerves brain spinal cord                nerve cell (neuron)       open pop-up dialog box           nerve cell (neuron)       open pop-up dialog box  open pop-up dialog box       close    nerve cell (neuron)   nerve cell (neuron) basic unit communication nervous system nerve cell (neuron)  nerve cell consists cell body  includes nucleus  major branching fiber (axon) numerous smaller branching fibers (dendrites)  myelin sheath fatty material covers  insulates protects nerves brain spinal cord           close    nerve cell (neuron)   nerve cell (neuron) basic unit communication nervous system nerve cell (neuron)  nerve cell consists cell body  includes nucleus  major branching fiber (axon) numerous smaller branching fibers (dendrites)  myelin sheath fatty material covers  insulates protects nerves brain spinal cord         close    nerve cell (neuron)   nerve cell (neuron) basic unit communication nervous system nerve cell (neuron)  nerve cell consists cell body  includes nucleus  major branching fiber (axon) numerous smaller branching fibers (dendrites)  myelin sheath fatty material covers  insulates protects nerves brain spinal cord      close    close  close nerve cell (neuron)   nerve cell (neuron) basic unit communication nervous system nerve cell (neuron)  nerve cell consists cell body  includes nucleus  major branching fiber (axon) numerous smaller branching fibers (dendrites)  myelin sheath fatty material covers  insulates protects nerves brain spinal cord   nerve cell (neuron) basic unit communication nervous system nerve cell (neuron)  nerve cell consists cell body  includes nucleus  major branching fiber (axon) numerous smaller branching fibers (dendrites)  myelin sheath fatty material covers  insulates protects nerves brain spinal cord  basic unit communication nervous system nerve cell (neuron)  nerve cell consists cell body  includes nucleus  major branching fiber (axon) numerous smaller branching fibers (dendrites)  myelin sheath fatty material covers  insulates protects nerves brain spinal cord  people infected virus causes polio  called poliovirus  don't symptoms  abortive polio 5% people poliovirus mild version disease called abortive poliomyelitis  leads flu-like symptoms last 2 3 days  include:  fever headache muscle aches sore throat stomachache loss appetite nausea vomiting  nonparalytic polio severe form disease  called nonparalytic polio  affects 1% infected  illness lasts longer days  doesn't cause paralysis  more-severe flu-like symptoms  nonparalytic polio symptoms may include:  neck pain stiffness aches stiffness arms legs severe headache  second phase symptoms may follow  person may days second phase starts  symptoms include:  stiffness spine neck decreased reflexes muscle weakness  paralytic polio form disease rare  disease begins like nonparalytic polio  progresses more-severe signs symptoms  including:  intense pain extreme sensitivity touch tingling pricking sensations muscles spasms twitching muscles weakness progressing limp paralysis  combination limbs may experience paralysis  paralysis leg common  followed paralysis arm  depending severity disease  signs symptoms may include:  paralysis muscles involved breathing difficulty swallowing  post-polio syndrome post-polio syndrome appearance new signs symptoms progression problems  happens decades polio  common signs symptoms include:  progressive muscle joint weakness pain fatigue muscle wasting breathing swallowing problems sleep-related breathing disorders  sleep apnea lowered tolerance cold temperatures 
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