While observing a synaptic end bulb, the investigator sees a decrease in the amount of neurotransmitter in the end bulb when the cell is stimulated, but then shortly thereafter, discovers that the amount of neurotransmitter in the cell seems to be increasing. One could hypothesize that the neurotransmitter is removed from this synapse by
A) diffusion
B) enzymatic degradation
C) reuptake by the neuron
D) uptake by glial cells

Question

Quizplus · Accepted Answer

The observation that the amount of neurotransmitter in the end bulb is decreasing upon stimulation suggests that the neurotransmitter is being released into the synaptic cleft. The subsequent increase in the amount of neurotransmitter suggests that it is being removed from the cleft and taken back up into the presynaptic neuron via reuptake. Diffusion is an unlikely mechanism for removing neurotransmitter from the synapse because it would not account for the observed increase in neurotransmitter levels. Enzymatic degradation and uptake by glial cells are also unlikely, as they would not result in an immediate increase in neurotransmitter levels following the initial decrease.

While Observing a Synaptic End Bulb, the Investigator Sees a Decrease