The Human Brain
<b>INTRODUCTION</b><br><br>The human body is divided into many different parts called organs. All of the parts are controlled by an organ called the brain, which is located in the head. The brain weighs about 2.75 pounds, and has a whitish-pink appearance. The brain is made up of many cells, and is the control centre of the body. The brain flashes messages out to all the other parts of the body. The messages travel in very fine threads called nerves. The nerves and the brain make up a system somewhat like telephone poles carrying wires across the city. This is called the nervous system.<br><br>The nerves in the body don't just send messages from the brain to the organs, but also send messages from the eyes, ears, skin and other organs back to your brain. Some nerves are linked directly to the brain. Others have to reach the brain through a sort of power line down the back, called the spinal cord. The brain and spinal cord make up the central nervous system.<br><br>The brain doesn't just control your organs, but also can think and remember. That part of the brain is called the mind.<br><br><b>PROTECTING THE BRAIN</b><br>Twenty-eight bones make up the skull. Eight of these bones are interlocking plates. These plates form the cranium. The cranium provides maximum protection with minimum weight, the ideal combination. The other twenty bones make up the face, jaw and other parts of the skull.<br><br>Another way the brain keeps it self safe is by keeping itself in liquid. Nearly one fifth of the blood pumped by the heart is sent to the brain. The brain then sends the blood through an intricate network of blood vessels to where the blood is needed. Specialized blood vessels called choroid plexuses produce a protective cerebrospinal fluid. This fluid is what the brain literally floats in.<br><br>A third protective measure taken by the brain is called the blood brain barrier. This barrier consists of a network of unique capillaries. These capillaries are filters for harmful