This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nervous system, Subject name: Physiology
Uni directional flow of a nerve impulse is at 
Select and explain. 
A. Synapse, B. Axon, C. Dendrites, D. Node of Ranvier
A: Synapse
Answer: A: Synapse 
Explanation: In the nervous system, a synapse is a structure that permits a neuron (or nerve cell) to pass an electrical or chemical signal to another neuron or to the target effector cell. Ref: guyton and hall textbook of medical physiology 12 edition page number: 675,676,677