Write one word for each of the following:

(i) The structural and functional unit of nervous system _____________

 

(ii) A wave of electrical disturbance that sweeps over the nerve cell. _____________

 

(iii) Long thread-like part of the nerve cell. _____________

 

(iv) Point of contact between two nerve cells. _____________

 

(v) A bundle of axons enclosed in a tubular sheath _____________

 

(vi) The kind of nerve carrying impulses from the brain to a gland or muscle. _____________

(i) The structural and functional unit of the nervous system: Neuron.

Explanation: The nervous system in our body consists of the brain, spinal cord, sense receptors and many nerves. But all these components are made up of the nerve cells called neurons. These neurons help in the transmission of electric signals called nerve impulses. Hence, they are referred to as the structural and functional units of the nervous system.

(ii) Wave of electrical disturbance that sweeps over the nerve cell: Nerve impulse.

Explanation: A wave of irritability is known as a nerve impulse. The nerve cells transmit these electric signals called impulse.

(iii) Long thread-like part of the nerve cell: Axon

Explanation: The axon is the long process from the cell body of the nerve cell. They are thin and longer than the dendrites and help in the transmission of a signal from one nerve cell to another.

(iv) Point of contact between two nerve cells: Synapse

Explanation: Synapse is the point of contact between the terminal branches of the axon of a neuron with the dendrites of another neuron separated by a fine gap. Here, the impulse “jumps” into the next neuron with the help a chemical called acetylcholine.

(v) A bundle of axons enclosed in a tubular sheath: Nerve

Explanation: Nerves are thread-like structures that emerge from the brain and spinal cord and extend to all parts of the body. A nerve consists of many axons wrapped up within a tubular sheath.

(vi) The kind of nerve carrying impulses from the brain to a gland or muscle: Motor Nerves

Explanation: The motor nerve helps in transmission of an impulse from the brain or spinal cord, to effector organs, muscles or glands to bring them into action on receiving the electric impulse.