Transmission non-myelinated free science lessons

• What should you be able to describe by the end of the video on action potentials?


  How an action potential is transmitted along a non-myelinated axon and the importance of the refractory period
• What is the resting state of a non-myelinated axon characterized by?


  A higher concentration of sodium ions outside and potassium ions inside the membrane
• What charge does the inside of the axon membrane have during the resting state?


  Negative charge relative to the outside
• What happens when a stimulus causes the membrane to depolarize?


  Voltage gated sodium ion channels open and sodium ions diffuse into the axon
• What is a localized electrical circuit in the context of action potential transmission?


  It refers to sodium ions moving sideways from one region to another, causing depolarization
• What occurs in region B after sodium ions diffuse into the axon?


  Region B depolarizes as sodium ions enter
• What happens to voltage gated sodium ion channels in region A after depolarization?


  They close and voltage gated potassium ion channels open
• What is the effect of potassium ions diffusing out of the axon in region A?


  Region A begins to repolarize
• How does the sodium-potassium pump contribute to the action potential process?


  It actively transports sodium ions out of the axon to restore resting potential
• What is the refractory period in the context of action potentials?


  It is the time during which a region of the membrane cannot transmit another action potential
• Why does the membrane need to repolarize after transmitting an action potential?


  To reestablish the electrochemical gradients for sodium and potassium ions
• What happens to voltage gated sodium ion channels after an action potential has passed?


  They cannot open again for a short period of time
• What are the three reasons the refractory period is important?


  • Ensures action potentials travel in one direction
  • Separates action potentials to prevent overlap
  • Limits the number of action potentials transmitted in a time period
• How does a stronger stimulus affect action potentials?


  A stronger stimulus generates a higher frequency of action potentials
• What is the maximum frequency of action potentials related to?


  It is limited by the refractory period
• What is the next topic to be covered in the following video?

  How an action potential is transmitted in a myelinated neuron
• What is the process called when action potentials are transmitted in myelinated neurons?


  Saltatory conduction