Nerve fibres conduct impulses in

Assertion : Transmission of nerve impulse across a synapse is accomplished by neurotransmitters.
Reason : Transmission across a synapse usually requires neurotransmitters because there is a small space,i.e.,synaptic cleft,that separates one neuron from another.

The functional junction between the axon of one neuron and the dendrite of the next is called

Which one of the following statements regarding nerve activity is true?

Assertion $(A) :-$ Impulse transmission across an electrical synapse is always faster than that across a chemical synapse.
Reason $(R) :-$ Electrical current can flow directly from one neuron into the other across electrical synapses.

Alzheimer's disease in humans is associated with the deficiency of