Human brain
![](http://upload.wikimedia.org/wikipedia/commons/thumb/5/58/Human_brain.png/100px-Human_brain.png)
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The human brain usually weighs 3lb (1.4kg) and is made up of wet tissues. The function and importance of the brain was widely unknown until recent centuries, Aristotle, thought the brain was a radiator for cooling the blood.
The human brain is made up of many parts, including: The Frontal-Polar Cortex, which is the most recently evolved part of the prefrontal cortex. This area of the brain assists in forward planning, and controlling other parts of the brain. The Frontal Lobe, which is the largest of the brains lobes, and the latest to evolve. The back of the frontal lobe mainly controls precise movements, and the front area, controls high-level planning. The Cortex is heavily folded, creating a large surface area.
![A model of a neuron](http://upload.wikimedia.org/wikipedia/commons/thumb/f/f0/Neuron_with_ALL_channels.jpg/220px-Neuron_with_ALL_channels.jpg)
On a cellular level, the human brain consists of about 86 million neurons, or brain cells. Every part of the human brain can be put into two classifications, grey matter and white matter. Grey matter consists of a neuron's dendrites, or tendrils. Grey matter is where neurons meet and interact. White matter is made out of the cell's body and is responsible for a brain signal staying intact and preserving the ionic energy that later gets transferred by grey matter.