The following diagram represents the human brain as seen in an external view. Study the same and then answer the questions that follow :

(i) Name the part labelled A, B, C and D.
(ii) Mention the difference in the arrangement of the nerve cells in the parts marked 'A' and 'D'
(iii) What is the main function of the parts marked 'C and 'D'?
(iv) Name the sheet of nerve fibres that connect the two halves of the part labelled.
(v) Name the basic unit of brain.

Explanation

(i) A - Cerebrum, B - Cerebellum
C - Medulla oblongata, D - Spinal cord
(ii) In part A - Grey matter is found outside and white matter is inside. In part D - White matter is outside and grey matter is inside.
(iii) Part C - Medulla oblongata, controls all involuntary movements of internal organs, e.g. breathing movements of lungs, beating of heart.
Part D - Spinal cord, performs reflex action below the neck.
(iv) Corpus callosum is the sheet of nerve fibres that connect the two halves of the parts labelled A (cerebral hemispheres).
(v) The basic unit of brain is called neuron