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Neurons and Synaptic Transmission, Psychoactive Drugs, Increased…

- - - - Nucleus (contains genetic material of cell)
    - - Carry nerve impulses from neighbouring neurons towards cell body
    - - Carries impulses away from cell body down length of neuron
    - - Covers axon and protects it to speed up electrical transmission of impulse
    - - Speed up transmission of impulse by forcing it to 'jump' across gaps along axon
    - - Communicate with next neuron in chain across synapse
  - - - Creates an electrical impulse that travels down the axon towards end of neuron
- - - - Once neurotransmitter crosses gap it's taken up by postsynaptic receptor site on dendrites of next neuron
        
        Here chemical is converted back to electrical impulse and process begins again
    - - Each neurotransmitter has its own specific molecular structure that fits perfectly into postsynaptic receptor site. They have specialist functions.
        
        E.g. acetylcholine (ACh) is found at each point where motor neuron meets muscle, upon release, causes muscles to contract.
  - - - Adrenaline
        
        Causes excitation of postsynaptic neuron by increasing its positive charge and making it more likely to fire
    - - Serotonin
        
        Causes inhibition in receiving neuron resulting in becoming negatively charged and less likely to fire
  - - - Excitatory and inhibitory influences are summed
        
        If net effect is inhibitory then postsynaptic neuron is less likely to fire. If net effect is excitatory then more likely to fire
        
        action potential of postsynaptic neuron is only triggered if sum of excitatory and inhibitory signals at any one time reaches the threshold