Question

Why is the flow of signals in a synapse from the axonal end of one neuron to dendritic end of another neuron but not the reverse?

Answer 1

The flow of signals through neurons takes place in the form of specialised chemicals called neurotransmitters. The neurotransmitters can only enter a neuron through dedicated receptor channels. Such receptor channels are only present at the dendritic end but not at the axonal end. Hence the flow of signals in a synapse happens from the axonal end of one neuron to the dendritic end of another neuron but not in the reverse direction.