***Brain and Nervous System***
What kind of supercomputer can write
stories, do math problems, draw pictures, play games, see through eyes, hear
someone talking, talk back, and network with devices that make snacks in the
microwave oven? Your brain and nervous system can do all these things. Do you
think a computer will ever be as powerful as your brain?
You think with your brain. Your
brain also sends signals through a network called your nervous system. It tells
your legs to walk and run. It tells your hands and arms to put popcorn in the
microwave. You don’t even have to think about many of the things your brain
does. Your brain tells your heart to beat. It tells your lungs to breathe in and
out, even when you are sleeping.
Your brain also controls your
feelings. Such feelings as joy, sadness, love, anger, and fear all come from
your brain.
WHAT IS MY BRAIN MADE OF?
Your brain is made of about 100
billion nerve cells. It looks like a lump of pinkish-gray jelly. The surface of
the brain is wrinkled, and deep grooves divide it into sections. A network of
blood vessels brings oxygen and food to your brain cells and carries away
wastes. Your brain is protected by bone called your skull. Liquid and skinlike
tissues also protect your brain.
When you were born, your brain
weighed about • pounds
(about 0.35 kilograms). Your brain keeps on growing while you grow up. By the
time you reach the age of 20, your
brain will weigh about 3 pounds (1.3
kilograms).
Your brain has three main parts.
The parts are called the cerebrum, the cerebellum, and the brain stem. The
cerebrum makes up the largest part of the brain. The cerebellum is underneath
the back part of the cerebrum. The brain stem connects with the spinal cord at
the bottom of the brain.
Your cerebrum and cerebellum are
divided into two parts. These parts are called the right brain and the left
brain. The right side of your brain controls the left side of your body. The
left side of your brain controls the right side of your body. Nerves from the
right and left side of your body cross over when they enter your brain.
WHAT DOES THE CEREBRUM DO?
Your cerebrum makes up most of
your brain. Your cerebrum solves problems and makes wishes. All of your thinking
goes on in your cerebrum. Speech, language, and emotions come from your
cerebrum, especially your cerebral cortex. The cerebral cortex is the outer part
of the cerebrum.
Your cerebrum also gets signals
from your senses. Nerves carry the signals. Nerves from your eyes and ears go to
parts of the cerebrum that let you see and hear. Nerves carry signals to your
cerebrum that let you feel, smell, and taste.
Your cerebrum sends messages out
along nerves. The messages tell your legs to walk or run. They tell your arm and
hand to wave when you see a friend across the street.
WHAT DOES THE CEREBELLUM DO?
Your cerebellum coordinates and
fine-tunes your body movements. Your cerebrum might tell your hands and arms to
hit a baseball. Your cerebellum controls how you swing the bat and make contact
with the ball.
Your cerebellum helps your fingers
play the piano, guitar, or violin. It helps you keep your balance when you run,
jump rope, or walk along a curb.
WHAT DOES THE BRAIN STEM DO?
Your brain stem takes care of all
the things that you do but don’t need to think about doing. It keeps your heart
pumping blood. It keeps your lungs breathing air. It makes your eyes blink. It
pulls your hand back really fast if you touch a hot pot on the stove.
WHAT IS THE NERVOUS SYSTEM?
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| Nervous System |
Your nervous system consists of
the brain, spinal cord, and nerves that run throughout your body. The nervous
system carries messages to your muscles and organs. These messages tell your
body what to do.
Your spinal cord is made of
bundles of nerves. It starts in your neck and goes down your back. Nerves go out
from the spinal cord to other parts of your body. Nerves from the spinal cord
extend to the tips of your fingers and toes. Your spine, or backbone, protects
your spinal cord.
Neuron
The nervous system is made of bundles
of cells called neurons. Neurons are found throughout your body. They send
electrical signals that direct all of your body’s activities, including
thinking, breathing, and moving. These signals travel along the length of one
neuron and jump to another neuron over a gap called a synapse.
