The following structures are involved in the protection of brain in animals

(i) Cranium There are 8 cranial bones which form the hard protective outer covering cranium for the brain.

(ii) Meninges The brain is covered with three membranes called meninges.

(a) Piamater Inner most membrane very thin, delicate and vascular and invests the brain closely.

(b) Arachnoid membrane It is like spider we in structure from which its gets its name.

(c) Duramater It is outer most, thick, tough fibrous membrane adhering closely to the inside of the skull.

(iii) Cerebrospinal fluid The cerebrospinal is present in the spaces between the meninges, i.e., arachnoid and duramater, which functions as a pad, absorbing shocks.

The inner part of cerebral hemispheres and a group of associated deep structures called limbic lobe or limbic system along with hypothalamus are involved in the above said functions, i.e., aggressive behaviour, use or abusive words, restlessness, etc.

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.