Action Potential Conduction

Question 1

Do AP’s decrease in amplitude as they are conducted?

Answer 1

No → they don’t decrease in amplitude as it moves down an axon bc you have the same ion concentrations along the length of the axon

Question 2

Where is decision of whether or not to generate an AP made?

Answer 2

axon hillock → it must be depolarized to the threshold to generate an AP

Question 3

Propagation of AP

Answer 3

• AP goes only in one direction bc of refractory period
• Na channels inactivated → sodium flows in a diffuses → rising phase moves down axon → falling phase (= when Na channels are inactivated = refractory period)

Question 4

Increase Membrane resistance

Answer 4

• Larger diameter
• High resistance
• Myelination
  
  • oligodendrocytes
  • schwann cells

Question 5

Myelination

Answer 5

• myelin sheath = extremely high resistance
• Saltatory conduction
  
  • doesn’t have to regenerate AP as much, only at nodes of Ranvier
• V-gated Na channels only in nodes of Ranvier in myelinated axons→
  
  • positive charges flow thru until they get to node→
  • less frequency of regeneration