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?
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.
