Synaptic Transmission

• What is the first step in synaptic transmission?

  information is passed down the axon to the terminal buttons as action potential (electrical impulse)
• How is action potential able to be passed to another neuron?

  Neurotransmitters crossing the synaptic cleft
• Where are the neurotransmitters stored?

  in vesicles in the terminal buttons
• How do neurotransmitters get released?

  vesicles containing neurotransmitters fuse with the membrane of terminal buttons and spill their contents into the synaptic cleft
• How do neurotransmitters move across the synaptic cleft?

  by diffusion from high concentration (presynaptic neuron) to low concentration (post synaptic neuron)
• What receptors are on the ends on dendrites (post synaptic neuron)?

  ion channel receptors
• What do neurotransmitters bind to after crossing the synaptic cleft?

  ion channel receptors on the end of dendrites (post synaptic neuron)
• What is meant by the lock and key model in synaptic transmission?

  neurotransmitters are specific to the ion channel receptors they try to bind to
• What model is used to describe the binding process of neurotransmitters to receptor cells?

  Lock and key model
• What is meant by the synaptic cleft?

  The small gap between neurons
• What happens at the end of synaptic transmission?

  either makes or prevents a postsynaptic neuron from firing an action potential
• What are excitatory neurotransmitters?

  make the postsynaptic neuron more likely to fire
• What are inhibitory neurotransmitters?

  make the postsynaptic neuron less likely to fire
• What happens if an excitatory neurotransmitter binds to a postsynaptic receptor?

  cause an electrical charge which results in excitatory postsynaptic potential (EPSP) -> makes it more likely to fire
• What happens if an inhibitory neurotransmitter binds to a postsynaptic receptor?

  cause an electrical charge which results in inhibitory postsynaptic potential (IPSP) -> makes it less likely to fire
• What is the name of the process where the axon hillock determines whether an action potential is fired or not?

  summation
• Describe the process of summation in synaptic transmission?

  the postsynaptic neuron receives multiple messages (IPSP & EPSP) from multiple synapses and the axon hillock compares the proportion between IPSP's and EPSP's and either makes or prevents the action potential firing
• What happens if there is a higher proportion of EPSP's during summation?

  action potential is fired
• What happens if there is a higher proportion of IPSP's during summation?

  action potential is not fired