The BrainInside the body thereís an organ that one uses to think, talk, listen look, hear, smell, taste, dream, feel, decide and remember. This sounds like a computer, a telephone, a camera, a television, and a scrapbook all wrapped up in one. Itís the brain that connects with the nerves to do all these things.
The brain is in charge of everything one does. Its sort of like the president of the body. It keeps the heart beating. It makes sense of the information coming to it from the sensory organs- the eyes, ears, nose, tongue, and skin. It sends orders all over the body. It stores information in memory. It reminds you what you did last week or so.
The human brain is pinkish- gray, wrinkled spongy organ. An adults brain weighs about three pounds. The brain is divided into three main parts - the cerebrum, the cerebellum, and the medulla.
The cerebrum is by far the biggest section, about nine tenths of your brain. Most brain activity takes place in the outer layer of the cerebrum, called the cerebral cortex. Its full of deep, wiggly grooves. Different parts of the cerebrum do different things. Some parts understand speech, other parts store memories, others control appetite, others control eye movement and so on.
Deep in the back of the brain lies the cerebellum. It coordinates the bodyís balance and movements.
Example: When you first ride a bicycle you have to concentrate really hard. Soon you learn to balance and move your body easily, without even thinking about what you are doing. When that happens your cerebellum is in control.
The medulla or brain stem, lies even deeper that the cerebellum. It controls involuntary body functions. These are the functions that go on without ones choosing to do them, such as the heartbeat, breathing and digestion.
The Nervous SystemYouíve probably seen telephone wires running from pole to pole, carrying messages back and forth from homes and businesses all over. It you imagine your brain as your central communication headquarters then you can think of your nerves as the wires running throughout your body.
The medulla connects the brain to a thick bundle of nerve fibers called the spinal cord. The spinal cord runs through the backbone, through a hole in each vertebra. The spinal cord connects to many nerves that stretch through the body, branching out to the legs, arms, toes and fingers.
The nerves carry messages back and forth to and from the brain. For example, when you lean down towards a rose, first your eyes send signals along special nerves to the brain. Your brain recognizes the image of a flower, then compares the image with others in your memory and recalls that this kind of flower often has a pleasant smell. Your brain send signals through your spinal cord and nerves to many muscles, giving the orders that make you bend towards the flower. Your brain then sends the message to breathe deeply. The scent of the rose comes into your nose, then signals of that scent travel through nerves to your brain.
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