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Neurons Part I

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					Neurons Part I
       Getting on your nerves
 Neurons of the nervous system function like a
  telephone network of interconnecting “wires”
  passing messages to and relying instructions
  from the CNS at speeds of up to 120 meters per
  second.
 Also like telephone wires these neurons are
  insulated by a myelin sheath (composed of a
  fatty substance) forming schwann cells.
 They are capable of more than 2.5 billion
  connections among themselves
                  Neurons:
 Basically they are elongated cells with two
  membrane extensions.
 Individual neurons line up end to end to form
  nerves which can receive, carry and conduct
  electrochemical impulses resulting from the
  movement of charged ions across the neuron
  membrane
 Communication between adjacent neurons is
  propagated by the action of chemical
  substances called neurotransmitters that
  conduct messages from one neuron to the next
  along a nerve fiber.
 Just like blood flow through the circulatory
  system nerve impulses are unidirectional!
        Label the Diagram:
               Dendrite

       Axon terminals
                                     Cell Body

       Schwann’s cell


         Node of Ranvier



Axon

       Myelin Sheath
                           Nucleus
     Three types of Neurons:
1. Sensory Neurons: receive stimuli and
  conduct impulses to the CNS
   AKA Afferent Neurons
   Have longer dendrites that are connected to
    specialized receptors depending on the type
    of information they are gathering
      Temperature
      Pressure
      Pain
      Chemical
      light
         Three types of Neurons:
2. Interneuron: nerve cell
  of the brain and spinal
  cord
    They have huge cell
     bodies as they must
     process the information
     coming in and produce
     the appropriate response
     instruction for messages
     going out of the CNS
     Three types of Neurons:
3) Motor Neurons: Conduct instructions from
  the CNS to muscle fibers
   They have long (myelinated) axons
              Reflex Arc:
 Some reflexive actions do not require the
  conduction of messages to the brain, but
  rather a short circuit at the spinal cord
  occurs
 These reflex arcs create an automatic,
  lightning fast motor response to stimuli
                  Reflex Arc:
 Sensory neurons
  conduct information
  to the spinal cord
  interneurons
 The interneurons
  immediately
  generate and
  conduct a response
  to the corresponding
  motor neuron for an
  immediate muscle
  contraction
Reflex Arc

				
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posted:4/9/2010
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