MDS entrance preparations | Unidirectional flow of a nerve impulse

Unidirectional flow of a nerve impulse is at:

A. Synapse 
B. Axon 
C. Dendrites 
D. All of the above

Ans. A 

Synapses generally permit conduction of impulses in one direction only, from presynaptic to post-synaptic neurons.

Any impulse conducted antidromically up the axons dies out because, post synaptical part of neurons lack chemical synaptic vesicles that are needed for synaptic transmission. Therefore an impulse arriving at the post synaptic membrane cannot release synaptic mediator. 

Axons can prevent impulses in both directions.

Dendrites are found on the axon’s endings and so behave in the same way as the axons i.e. bi-directional.