Electrical stimulation of a dorsal root fiber that synaptically connects with a motoneuron is observed to cause an electrotonic depolarization of the postsynaptic motoneuron. Which of the following changes in ion channels is the most likely cause for this depolarizing potential?
A)Closing of ligand-gated cation channel
B)Closing of voltage-gated anion channel
C)Opening of ligand-gated cation channel
D)Opening of voltage-gated anion channel

Question

Quizplus · Accepted Answer

If an electrical stimulation causes a depolarization of a postsynaptic motoneuron, it means that there is an influx of positive charge. The only option that would cause this is the opening of a ligand-gated cation channel, which allows positive ions such as Na+ or Ca2+ to enter the cell. Closing of a ligand-gated cation channel or opening of a voltage-gated anion channel would cause a hyperpolarization, while closing of a voltage-gated anion channel would have no effect on the membrane potential.

Electrical Stimulation of a Dorsal Root Fiber That Synaptically Connects