The Nervous System

Central Nervous System - Consists of:
1. Brain
2. Spinal Cord
PNS - Consists of:
1. Everything leading to and from the CNS
  1. 12 Cranial Nerve
  2. 31 Pairs of Spinal Nerves
2. Somatic
  1. Skeletal Muscle
  2. Convey from mainly external receptors
3. Autonomic
  1. Convey from mainly internal receptors
  2. Sympathetic/Parasympathetic
    1. fight or flight
    2. Digestion, Urination
Integrating System
Neurons
1. Functional unit of the nervous system
  1. Synapses
    1. Axon meets the dendrite of another
      1. Synaptic buton
        Voltage gated Calcium channels
        Ca++ enters cell and released neurotransmitter
    2. Synaptic cleft
    3. Post synaptic recptors are ligand gated
      1. Sodium Channel
        Produce a positive voltage
        Stimulation - something happen, continue delpolarisation
      2. Chlorine
        Produce a negative voltage
    4. Several presynaptic, synapse on same post synaptic - info is lost. (convergence)
    5. Presynaptic head meets sevel post synaptic - Info spread (diviergence)
  2. Neurotransmitters
    1. Acetylcholine
2. Axon
3. Cell body
4. Dendrite
  1. Recieve incoming info
5. Unipolar/Bipolar/Multipolar
resting - Pump sodium out of the cel, creating a - charge inside the cell compared to the outside
1. Sodium channels are closed - no way to reenter
  1. However when a neuron is stimulated, these channels open
    1. This creates a positve charge inside as the sodium moves in.
      1. Ion channels are voltage gated.
2. ALL OR NONE!
Myelination
1. CNS = Oligodendycites
2. PNS= Schwann Cells
Saltortary Conduction
Glial Cells
1. CNS
  1. ASTROCYTES = Nutrition
  2. Microglia = Removal of debris
Neuronal cell body collections
1. Ganglia = PNS
2. Nuclei =CNS

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