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The Nervous System
Ch 33 AND Ch 34
Electron Micrograph of Neurons
Main Divisions
of the Nervous System
Central Nervous System
• All nerves in the brain & spinal cord
(runs from brain to tailbone).
Peripheral Nervous System
• The PNS, consists of the nerves and
neurons that reside or extend outside the
central nervous system
• It is divided into two further divisions:
– somatic nervous system
– autonomic nervous system
Organization of the
Nervous System
Parts of a Neuron
Neuron Anatomy
• 1. Dendrites:
• 2. Cell Body: 3.
• Axon:
• 4. Axon Terminals:
• 5. Myelin Sheath:
• 6. Synapse:
The Physiology
of the Nervous System
•Resting Potential
•Action Potential
•Synapses
Resting Potential
Moving the ImpulseThe Action Potential
Channel Gating during an
action potential
• http://www.blackwellpublishing.com/matthe
ws/channel.html
Action Potential- all or none
• Step 1
• Step 2 (Depolarization)
• Step 3 (Repolarization)
•
Fig 33.7
Recharging the membrane
Propagation of the action
potential.
• http://www.blackwellpublishing.com/matthe
ws/actionp.html
Synapses
What happens at the axon
terminals?