Synaptic Transmission

• what is synaptic transmission?

  the process by which a nerve impulse is transmitted from the pre-synaptic to post-synaptic cell membrane
• how long does synaptic transmission take?

  a fraction of a second
• what is the space between the pre-synaptic and post-synaptic neuron called?

  the synaptic gap
• what are neurotransmitters?

  chemical messengers that transmits signals across a synapse from one neuron to another
• what is an example of a neurotransmitter?

  dopamine
• what are synaptic vesticles?

  sacs that contain the chemical messengers (neurotransmitters) that assist in the transfer of the impulse
• where are the synaptic vesticles located?

  at the end of the axon of the nerve cell
• what is the role of the pre-synaptic nerve ending?

  it releases neurotransmitters into the synaptic cleft, facilitating communication with the post-synaptic neuron
• what happens to the synaptic vesticle when the action potential reaches them?

  it releases the neurotransmitters and it diffuses across the synaptic gap, where it binds onto specialised receptors on the surface of the cell
• what is the post-synaptic nerve?

  the neuron that receives signals from the pre-synaptic neuron at a synapse
• what happens when neurotransmitters are activated?

  the receptor molecules produce either excitatory or inhibitory effects on the post-synaptic neuron
• what does the term excitatory mean in relation to neurotransmitters?

  the cell is more likely to fire because it has a positive charge
• what are examples of excitatory neurotransmitters?

  acetylcholine and noradrenaline
• what happens when an excitatory neurotransmitter binds with a postsynaptic receptor?

  it causes an electrical change in the membrane of the cell which results in an excitatory postsynaptic potential (EPSP)
• how can EPSP's be strengthened?

  by spatial and temporal summation
• what is spatial summation?

  when a large amount of EPSP's are generated at many different synapses on the same postsynaptic neuron at the same time
• what is temporal summation?

  when a large number of EPSP's are generated at the same synapse by a series of high-frequency action potentials on the presynaptic neuron
• what does the term inhibitory mean in relation to neurotransmitters?

  they decrease the likelihood of a cell firing as the cell has a negative charge
• what is the role of the inhibitory neurotransmitter?

  it calms the mind, induces sleep, and filters out unnecessary excitatory signals
• what are examples of inhibitory neurotransmitters?

  GABA, serotonin
• what happens when an inhibitory neurotransmitter binds with a postsynaptic receptor?

  it causes an electrical change in the membrane of the cell which results in an inhibitory postsynaptic potential (IPSP)