Heroin was first developed in __________

At approximately _____ pounds, the fetus may now be viable if born early

A) 2 B) 3 C) 4 D) 5

According to the all-or-none law, ____

a. all neurons produce an action potential at the same time or none at all b. all of the extracellular sodium enters the axon, or none at all c. once an axon reaches threshold, the amplitude and velocity of an action potential are nearly equal each time d. neurons are either active all the time or not at all