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Human body

Brain

The cerebrum, seen from above.The cerebrum, seen from above. Protected and supported within the skull, the brain is a soft, wrinkled organ, pinkish-grey in colour. As the control centre of the nervous system, it controls everything we do and every thought we have. The brain works all the time, even when we are asleep. It receives vast amounts of information from outside and inside the body, processes and analyses it, then makes decisions and sends out instructions. In this way, the brain automatically monitors and controls your heart and breathing rates. It co-ordinates your movements, gives you your personality and enables you to think, feel, remember and have feelings. 

Parts of the brain

The brain has four main parts: the brain stem, diencephalon, cerebellum and cerebrum. The brain stem links, and relays signals between the brain and spinal cord. It automatically controls many activities, including breathing and heart rates, eye movements and sleep. The diencephalon consists of the thalamus and hypothalamus. The thalamus sorts incoming sensory signals, passing them to the cerebrum. The tiny hypothalamus monitors and regulates many body activities, including temperature, thirst, hunger and sleep patterns, as well as controlling much of the hormone system.A cross-section through the brainA cross-section through the brainThe third part, the cerebellum, is responsible for co-ordinating the skeletal muscles to ensure that that body movements are smooth, controlled and not jerky. The cerebrum, the fourth part, makes up about 85% of the brain’s mass. It is the seat of thought, intelligence, feeling, memory, and movement. Like the cerebellum, the cerebrum has two hemispheres, left and right, linked by masses of nerve cells.


The folding of the cerebral cortex triples the surface area of the brain to about 2200 sq cm (340 sq inches). Two-thirds of that area is "hidden" within the folds.

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