Synapses

• What is a synapse?

  Connection between two neurons
• What are the components at either end of a synapse?

  Axon terminal and dendrites
• What is the role of synapses in the brain?

  They allow signals to pass between neurons
• What type of synapses are we focusing on?

  Chemical synapses
• What chemical is used to pass signals in chemical synapses?

  Neurotransmitter
• What is an example of a neurotransmitter?

  Acetylcholine
• What triggers the release of neurotransmitters from vesicles?

  Action potential opens voltage-gated calcium channels
• What happens when calcium ions enter the pre-synaptic neuron?

  They enable vesicles to attach to the pre-synaptic cleft
• What occurs after neurotransmitters are released into the synaptic cleft?

  They dock with receptors on the post-synaptic neuron
• What ions rush into the post-synaptic neuron when receptors open?

  Sodium ions
• What does the influx of sodium ions create in the post-synaptic neuron?

  Action potential
• How does repeated firing of a synapse affect its strength?

  It strengthens the synapse by increasing receptors
• How many neurons does the human brain have?

  About 100 billion neurons
• How many synapses does each neuron have?

  About 1,000 to 10,000 synapses
• What can happen to synapses over time?

  They can strengthen or weaken
• How wide is the synaptic cleft?

  Less than five millionths of a centimeter
• How do many drugs affect neurotransmitters?

  They interfere with neurotransmitter function
• What can happen if neurotransmitters do not function properly?

  Several diseases can occur
• What is the biological reason for revising?

  To strengthen neural pathways
• What is the sequence of events in neurotransmitter release across a synapse?

  1. Action potential arrives at axon terminal
  2. Voltage-gated calcium channels open
  3. Calcium ions enter pre-synaptic neuron
  4. Vesicles attach to pre-synaptic cleft
  5. Neurotransmitters are released into synaptic cleft
  6. Neurotransmitters bind to receptors on post-synaptic neuron
  7. Sodium ions rush in, creating action potential
• What are the key terms related to synapses that should be known?

  • Synapse: link between two neurons
  • Pre-synaptic neuron: before the synapse
  • Post-synaptic neuron: after the synapse
  • Synaptic cleft: gap between neurons
  • Vesicles: carry neurotransmitters
  • Acetylcholine: important neurotransmitter
  • Docking proteins: assist vesicle attachment
  • Receptors: bind neurotransmitters on post-synaptic neuron