A. $\rightarrow(3)$ B. $\rightarrow$ (4) C. $\rightarrow$ (2) D. $\rightarrow$ (1)

	Column I		Column II
A.	Resting potential	1.	Electrical potential difference across the resting neural membrane.
B.	Nerve impulse	2.	An electrical wave like response of a neuron to a stimulation.
C.	Synaptic cleft	3.	Gap between the pre-synaptic and pos-synaptic neurons.
D.	Neurotransmitters	4.	Chemicals involved in the transmission of impulses at synapses.

The major parts of the human neural system is filled in the boxes with appropriate words

Differences between electrical transmission and chemical transmission are as given below

Electrical Transmission	Chemical Transmission
It occurs at electric synapse.	It occurs at chemical synapse.
Synaptic cleft may or may not be present.	synaptic cleft is present.
At electrical synapses, electrical current can flow directly from one neuron into the other across these synapses.	At chemical synapse, neurotransmitter from pre-synaptic neurons transfer to post-synaptic neurons leading to transmission of impulse.
Impulse transmission across an electrical transmission is always faster.	Chemical transmission is slower.

The sensory neurons present in various organs sense the environment and extend the message to the brain. So, it is equivalent to input device of computers. Brain acts as CPU, i.e., Central Processing Unit. The information gathered by sensory neurons is processed by brain and it gives command to the concerned organ to act accordingly. This message is taken or conveyed by motor neurons which act as output devices.

If a person receives a blow on the back, then it will lead in an impairment of cognitive abilities or physical functioning. It can also result in the disturbance of behavioural or emotional functioning. Cervical injuries often lead to quadriplegia (tetraplegia).