The Nervous System

The Nervous System

1. Central Nervous System - Consists of:

   • Brain
   • Spinal Cord

2. PNS - Consists of:

   • Everything leading to and from the CNS
     • 12 Cranial Nerve
     • 31 Pairs of Spinal Nerves
   • Somatic
     • Skeletal Muscle
     • Convey from mainly external receptors
   • Autonomic
     • Convey from mainly internal receptors
     • Sympathetic/Parasympathetic
       • fight or flight
       • Digestion, Urination

3. Integrating System

4. Neurons

   • Functional unit of the nervous system
     • Synapses
       • Axon meets the dendrite of another
         • Synaptic buton
           • Voltage gated Calcium channels
             • Ca++ enters cell and released neurotransmitter
       • Synaptic cleft
       • Post synaptic recptors are ligand gated
         • Sodium Channel
           • Produce a positive voltage
             • Stimulation - something happen, continue delpolarisation
         • Chlorine
           • Produce a negative voltage
       • Several presynaptic, synapse on same post synaptic - info is lost. (convergence)
       • Presynaptic head meets sevel post synaptic - Info spread (diviergence)
     • Neurotransmitters
       • Acetylcholine
   • Axon
   • Cell body
   • Dendrite
     • Recieve incoming info
   • Unipolar/Bipolar/Multipolar

5. resting - Pump sodium out of the cel, creating a - charge inside the cell compared to the outside

   • Sodium channels are closed - no way to reenter
     • However when a neuron is stimulated, these channels open
       • This creates a positve charge inside as the sodium moves in.
         • Ion channels are voltage gated.
   • ALL OR NONE!

6. Myelination

   • CNS = Oligodendycites
   • PNS= Schwann Cells

7. Saltortary Conduction

8. Glial Cells

   • CNS
     • ASTROCYTES = Nutrition
     • Microglia = Removal of debris

9. Neuronal cell body collections

   • Ganglia = PNS
   • Nuclei =CNS