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CENTRAL NERVOUS SYSTEM

Q1. What does the Central Nervous System comprise of?
The brain and the spinal chord, along with nerves constitute the Central Nervous System. BRAIN: is located in side the skull (Brain case). SPINAL CHORD: is located in the verteral column - on the back of our body - from neck to anus.
Q2. What is the weight of the brain and how much of the body weight it constitute of?
The brain weighs about 1.4 kg for men and 1.3 kg for women, which accounts for 3% of average body weight of a person.
Q3. What are the other physical features of the Brain?

(1) It contains about 10,000 neurons - microscopic nerve cells.
(2) It has about 100 billion of neurons.
(3) It contains 75-80% of liquid (water).
(4) Dies after 3 minutes of a person's death as the blood circulation stops.
(5) Consumes about 20% of the oxygen inhaled, 20% of calories a person consumes and uses about 15% of body's blood.
Q4. What are the various segments of the CNS?
It consists of:
CEREBRUM: The largest part of the brain, consisting of two hemispehres separated by CORPUS CALLOSUM - a deep median furrow. It controls voluntary actions and is the seat of intelligence, memory association, imagination and will.
CEREBELLUM: The large mass having ridges and furrows, situated above and behind the mediulla and attached to cerebrum. It regulates muscular movement of locomotion.
MEDULLA OBLONGATA: It is the lower most part of the brain which continues as the spinal chord in the vertebral column. It controls involuntary action.
SPINAL CHORD: Is the elongated, nearly cylindrical constitution of the medulla. It is enclosed in the vertebrae and runs down the back. The length of the spinal chord is an average man is about one metre - 3.3 feet.
NERVES: Are whitish cords consisting of large numbers of exceedingly fine filaments (nerve fibres) of variable diameter, bound together in bundles of fibrous tissues.
Q5. What are the functions of the nerves?
They transmit messages (nerve impulses) from and to the central nervous system to the various parts of the body. The nerve fibres which carry the impulses and pass them to the muscles to make them contract are called MOTOR NERVE FIBRES. Those nerves which carry information from the skin and tissues evokes a sensation within the nervous system and thus called SENSORY NERVOUS FIBRES.
Q6. What is the general classification of nerves?
They are classified into two groups:
(1) CRANIAL NERVES: Attached to the brain and emerge from the skull.
(2) SPINAL NERVES: Attached to the spinal chord, enclosed in the vertebrae. There are 31 pairs of them named after the vertebrae groups between which they emerge: Cervical Nerves - 8; Thoracic - 12; Lumbar - 5; Sacral - 5; and Coccygeal -1.
Q7. What controls the functioning of the body at sleep?
Automatic nervous system.
Q8. What is responsible for the transmission of messages in the body?
ACETYL CHOLAINE a chemical produced in the neurons (nerve cells).
Q9. What are the names for the sensory nerves and the motor nerves?
Sensory - Afferent; Motor - Efferent.
Q10. How many pairs of spinal nerves are there?
31 pairs.
Q11. How many cranial nerves are there in the human body?
12 pairs.
Q12. What is brain size of average modern man?
1600 cc.
Q13. Which membrane connects the brain and the spinal chord?
Meninges.
Q14. Which part of brain controls body temperature?
Hypothalamus.
Q15. How many neurons are there in the brain?
1400 crores.
Q16. The venom of which animal acts on CNS?
Cobra.
Q17. The long nerve cell that carries away the impulses from the body?
Axons.
Q18. Which part of the brain is endocrine in nature?
Hypothalamus - (Endocrine means - any gland producing one or more internal secretions).
Q19. Which side of the brain controls the right side of the body?
Left.
Q20. Which part of the brain is known as "Little Brain"?
Cerebellum.
Q21. What is the longest and largest nerve in the human body?
Sciatic.
Q22. How the fore brain is called ?
Cerebrum.