Grey matter is a major component of CNS consisting of neuronal cell bodies, dendrite, unmyelinatedaxous, glial cells and capillaries. White matter is also a component of CNS and consists mostly of glial cell and myelinated axons.

Hypothalamus contains many centres which control urge for eating and drinking.

The symptoms of dizziness and vomiting, faced by a person travelling at higher altitude is because of the following resaons

(i) The function of Eustachian tube is to equalise the pressure on either sides of the ear drum; sudden elevation in height causes disturbance in maintaining pressure by this area of ear.

(ii) The semicircular ducts, the anterior, posterior and lateral semicircular ducts, are enlarged at one end to give rise to ampulla. Each ampulla contains sensory path of hairs, the cristae, which is concerned with the balancing of the body, Change in altitude brings changes in the reorientation and adjustments in these structures of internal ear causing the above said symptoms.

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