biopsychology: neurons and synaptic transmission

basics
1. the structure and function of neurons
  1. 100 billion neurons in the human nervous system
    1. 80% are in the brain
      1. transmit signals electrically and chemically
        communicate
2. types of neuron
  1. 3 types
    1. motor neurons
    2. sensory neurons
    3. relay neurons
3. the structure of a neuron
  1. different sizes (mm - metre)
    1. structure
      1. cell body
        includes the nucleus
        contains the genetic material
      2. dendrites
        attached to the cell body
        carry nerve impulses from neighbouring neurons towards the cell
      3. axon
        carries impulse away from the cell body
        down the length of the neuron
        covered in a fatty layer (myelin sheath)
        protects it and speeds up transmission
      4. nodes of ranvier
        myelin sheath split up to make impulses quicker
        these are called nodes of ranvier
      5. terminal buttons
        end of the axon
        speed up transmission forcing it to jump across the gaps along the axon
4. electric transmission - the firing of a neuron
  1. when neuron in resting state the inside is negatively charged compared to the outside
    1. when it is activated by a stimulus the inside becomes positively charged
      1. causing an action potential
        creates electrical impulses that travel down the axon
synaptic transmission
1. chemical transmission - synapses
  1. neurons communicate within groups called neural networks
    1. each neuron separated by a gap called a synapse
      1. signals within neurons transmitted electrically
        outside chemically (along the synapse)
        when the electrical impulses reach the end of the neuron (presynaptic terminal) it triggers the release of neurotransmitters fro sacs called synaptic vesicles
2. neurotransmitter
  1. chemicals that diffuse across the synapse to the next neuron
    1. when a neurotransmitter crosses the synapse it reaches the post synaptic gap
      1. the dendrite of the next neuron
        the chemical message changes to electrical and carries on
        several types of neurotransmitters are in the brain, spinal cord and some glands
        has its own structure that fits perfectly into the post synaptic receptor site
        all have special functions
3. excitation and inhibition
  1. neurotransmitters have either an excitatory or inhibitory effect
    1. serotonin causes inhibition resulting in he neuron becoming negatively charged so less likely to fire
      1. adrenaline causes excitation makes it positively charged so more likely to fire

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biopsychology: neurons and synaptic transmission

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