Sending Signals Notes

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Sending Signals Notes
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Structure of Single Neuron
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Neurons

• http//facweb.gsw.edu/gfisk/anim/neuronparts.swf

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3 types of Neurons Sensory Neurons neurons
that carry incoming information from the sense to
the CNS Interneurons CNS neurons that
internally communicate and intervene between the
sensory inputs and motor outputs Motor Neurons
Carry outgoing information from the CNS to muscle
and glands
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Sensor Receptor
Sensory Input
Integration
Effector
Motor Output
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Neuron SignalsACTION POTENTIAL
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• The point of contact at which impulses are passed
  from one cell to another are known as THE
  SYNAPTIC CLEFT OR SYNAPSE.
• Neurons that transmit impulses to other neurons
  DO NOT actually touch one another.  The Small Gap
  or Space between the axon of one neuron and the
  dendrites of the next neuron is called the
  Synapse. 
• One importance of the presence of Synapses is
  that they ensure one-way transmission of impulses
  in a living person. 
• The Axon Terminals at a Synapse contain tiny
  vesicles, or sacs. These are known as
  NEUROTRANSMITTERS.

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• NEUROTRANSMITTER is a chemical substance that is
  used by one neuron to signal another.  The
  impulse is changed from an Electrical Impulse to
  a Chemical Impulse (Electrochemical Impulses).

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Other facts

• After the neurotransmitter relays it message it
  is rapidly REMOVED or DESTROYED, thus halting its
  effect.
• Neurotransmitters may be broken down by ENZYMES,
  taken up again by the axon terminal and recycled,
  or they may simply diffuse away.
• NERVE GAS prevents enzymes from breaking down
  neurotransmitters, as a result muscles in the
  respiratory and nervous system becomes paralyzed.
  

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The End

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• When an impulse reaches the Axon Terminal, dozen
  of vesicles fuse with the cell membrane and
  discharge the Neurotransmitter into the Synaptic
  Cleft (GAP).
• The molecules of the neurotransmitter diffuse
  across the gap and attach themselves to SPECIAL
  RECEPTORS on the membrane of the neuron receiving
  the impulse.
• When the neurotransmitter becomes attached to the
  cell membrane of the adjacent nerve cell, it
  changes the permeability of that membrane.
• As a result, Na ions diffuse through the
  membrane into the cell.
• If enough neurotransmitter is released by the
  axon terminal, so many Na ions diffuse into the
  neuron that the neuron becomes DEPOLARIZED.

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• DEPOLARIZED Inside the membrane becomes more
  positive than outside.
• This causes a THRESHOLD to be REACHED and an
  impulse (ACTION POTENTIAL) begins in the second
  cell.
• After the neurotransmitter relays it message it
  is rapidly REMOVED or DESTROYED, thus halting its
  effect.
• The molecules of the neurotransmitter may be
  broken down by ENZYMES, taken up again by the
  axon terminal and recycled, or they may simply
  diffuse away.
• NERVE GAS prevents enzymes from breaking down
  neurotransmitters, as a result muscles in the
  respiratory and nervous system becomes paralyzed.

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Action Potentials

• http//facweb.gsw.edu/gfisk/anim/actionpotential.
  swf