Answer to Question 1
ANS: D
Drugs that interfere with termination of transmitter action do so by blocking transmitter reuptake or inhibiting transmitter degradation, resulting in increased receptor activation, because more of the transmitter remains available. Diffusion of the transmitter occurs naturally, but it is a slow process with little clinical significance. Drugs that alter this process cause a decrease in reuptake, not an increase. The effect of drugs that interfere with termination of transmitter action is increased activation.
Answer to Question 2
ANS: A
Local anesthetics are the only drugs shown to work by altering axonal conduction. Any drug affecting axonal conduction would be nonselective, because axonal conduction of impulses is essentially the same in all neurons. In contrast, drugs that affect synaptic transmission can be highly selective, because each transmitter has different effects on receptor sites. Most PNS drugs work on synaptic transmission processes. Through their effects on transmitters, they influence receptor activity.
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