August 9, 2014

HUMAN BRAIN - Structure, Functions & Diseases Explained

The human brain consists of two parts, namely, the brain lodged in the brain case (skull) and the spinal cord lodged in the vertebral column.

General Facts about Human Brain
  • The human brain has two sides. The right side and the left side. The right side controls the left half of the body and the left side controls the right half of the body.
  • The Skull protects the brain its is composed of 22 Bones.
  • The weight of the average human brain triples between birth and adulthood. The final weight of the brain in an adult male is about 1.4 kg and 1.3 kg in the case of a woman, which averages about 3 per cent of body weight of a normal person.
  • The brain uses about 20 per cent of the oxygen a man breathes, 20 per cent of calories a man takes in and about 15 per cent of body blood.
  • The average brain contains about 100 billion neurons—microscopic nerves cells.
  • The human brain is the largest and most powerful sex organ.
  • Our brain is 80% water.
  • Our brain is move active and thinks more at night than during the day.
  • The Brain cells will never be replaced.

Central nervous system :
The brain and the spinal cord, along with nerves, constitute the nervous system. The brain consists of
(i)         Cerebrum: The largest part of the brain, consists of two hemispheres separated by corpus callosum, a deep median furrow. It controls voluntary actions and is the seat of intelligence, memory association, imagination and will.
(ii)        Cerebellum: Attached to cerebrum and situated next to the medulla, this is a large mass having ridges and furrows. It regulates muscular movement of locomotion.

(iii)       Medulla oblongata: It is the lowermost part of the brain, which continues as the spinol chord in the vertebral column. It controls involuntary action.
(iv)       Spinal cord: It is the elongated, nearly cylindrical continuation of the medulla. It is enclosed in vertebrae and runs down the back. The length of the spinal cord in on average man is about 1 metre (3.3 ft).
(v)        Nerves: Whitish cords consisting of large numbers of exceedingly fine filaments (nerve fibres) of variable diameter, nerves ore bound together in bundles by fibrous tissues.

Function of nerves:
Nerve fibres transmit messages (nerve impulses) (both to and fro) from the central nervous system to various ports of the body. The fibres that carry impulses from the central nervous system are called efferent. Many of these pass to the muscles to make them contract and are, therefore, called motor nerve fibres. Those carrying impulses to the central nervous system are called afferent fibres. The information they transmit from the skin and deeper tissues often evokes subjective sensation within the nervous system, hence, they are called sensory nerve fibres.

Classification of nerves:
(i) Cranial nerves are attached to the brain and emerge from the skull (cranium).
(ii) Spinal nerves are attached to the spinal cord, which is enclosed in the vertebral column.

Brain Imaging Tools:
Computed tomography (CT) scan—to take images of your brain.
Magnetic resonance imaging (MRI)
Positron emission tomography (PET).

Diseases & Disorders of Brain:
  • Alzheimer’s disease, may manifest as you age and slowly impair your memory and thought processes.This progressive disease damages nerve cells in parts of the brain involved in memory, learning, language, and reasoning. In early stages, short-term memory begins to fail.
  • Tay-Sachs disease, begin at an early age. Tay-Sachs disease affects a child’s mental and physical capabilities. 
  • Tumors can develop in the brain’s tissue and cause many problems, including preventing blood circulation in the brain. These growths may be cancerous or benign.
  • Parkinson’s disease
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