Question

Give reasons:-
1. Nerve Impulses are unidirectional
2.Neurons have branched structures called dendrites.
3. Certain actions are very quick,without involving brain

Answer 1

1 So that the impulse reaches the central nervous system quickly and do not return back.
2 To collect nerve impulses coming from various directions.
3 Certain stimulus requires quick action or our body may be harmed. These are called reflex action. These actions get interpretated in the spinal cord instead of brain.

Answer 2

1. Nerve impulses are unidirectional due to there only destination to brain.They do not have to go anywhere else, hence they move only in one direction and that is to brain.

2. Neurons have branched structures called dendrites to receive the nerve impulses from the other neuron and to pass it to axon to pass the nerve impulse to the further neurons.

3. Some actions are very quick, not fully they do not involve brain. These type of actions are known as reflex actions which need a much faster response then any other type of stimulus