Question

In the lab, two axons are tested for propagation velocities. One carries action potentials at 10 meters per second, the other at 1 meter per second.  

a.      Which axon is mylelinated? Explain why.

b.      What cell(s) could be added to the unmyelinated axon in order to increase the propagation velocity?  

c.      What would the addition of the snake venom Curare to the myelinated axon cause to the propagation

Answer 1

1. The axon with propagation velocity of 10m/s is myeinated. Myelinated axons transmit action potential at a faster rate than unmyelinated axons because of the presence myelin which acts as insulating source for faster conduction of signals.

2. Schwann cell could be added to the unmyelinated axon in order to increase the propagation velocity because as they can envelop unmyelinated axon with multiple layers of myelin.

3. Snake venom curare is snake neurotoxin. Addition of this neurotoxin to myelinated axons leads to degradation of myelin sheath due to the presence of very high percentage of phospholipase A_2.