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

The flow of signals in a synapse from axonal end of one neuron to dendritic end of another neuron takes place by the means of specialized chemicals called neurotransmitters. When an electrical signal reaches the axonal end of a neuron, it releases a chemical substance. This chemical diffuses towards the dendrite end of next neuron where it generates an electrical impulse or signal. Hence, the electrical signal is converted into a chemical signal at the axonal end. Hence, the flow of signals in a synapse happens from axonal end of one neuron to dendritic end of another neuron but not in the reverse direction.