When anesthesia or toxins, such as tetrodotoxin from the puffer fish, block a sodium channel, they
A)prevent an action potential from occurring.
B)cause a negative after-potential to occur.
C)decrease the amount of dopamine at the receptor sites.
D)cause an excessive release of acetylcholine into the synaptic cleft.

Question

Quizplus · Accepted Answer

When a sodium channel is blocked, it prevents the influx of sodium ions into the cell, which is necessary for depolarization and the initiation of an action potential. Therefore, the correct choice is A.

When Anesthesia or Toxins, Such as Tetrodotoxin from the Puffer