neurons & synaptic transmission

• How many neurons are in the human nervous system?

  100 billion
• Where are 80% of neurons located?

  In the brain
• How do neurons transmit signals?

  Electrically and chemically
• What happens when a neuron is activated by a stimulus?

  The inside becomes positively charged
• What is an action potential?

  An electrical impulse traveling down the axon
• What is synaptic transmission?

  • Electrical message from presynaptic neuron
  • Chemical message at the synapse
  • Received by postsynaptic neuron
• What is excitation in neuronal communication?

  Neuron is more likely to fire a message
• What is inhibition in neuronal communication?

  Neuron is less likely to fire a message
• What is summation in neuronal communication?

  Net effect of the neurotransmitter
• Why can neurons only transmit information in one direction at a synapse?

  Receptor sites are only on postsynaptic neuron
• What is the main component of the cell body?

  Nucleus
• What is the function of the nucleus in a cell?

  It contains the genetic material of the cell
• What do dendrites do?


  Carry nerve impulses towards the cell body
• How do dendrites interact with neighboring neurons?

  They receive nerve impulses from neighboring neurons
• What is the role of the axon?


  It carries impulses away from the cell body
• What does the myelin sheath do?


  It protects the axon and speeds up transmission
• What is the myelin sheath made of?


  A fatty layer
• What are the nodes of Ranvier?


  Gaps within the myelin sheath
• How do nodes of Ranvier affect impulse transmission?


  They speed up transmission by forcing impulses to jump
• Where are terminal buttons located?


  At the end of the axon
• What is the function of terminal buttons?

  They communicate with the next neuron across the synapse
• What are the main structures of a neuron and their functions?

  • Cell Body: Contains the nucleus
  • Nucleus: Contains genetic material
  • Dendrites: Carry impulses towards the cell body
  • Axon: Carries impulses away from the cell body
  • Myelin Sheath: Protects axon and speeds up transmission
  • Nodes of Ranvier: Gaps that speed up impulse transmission
  • Terminal Buttons: Communicate with next neuron across synapse