The Brain
The brain is a soft, spongy mass of
tissue. It is protected by the bones of
the skull and three thin membranes
called meninges. Watery fluid called
cerebrospinal fluid
cushions the brain. This fluid flows through spaces between the meninges and
through spaces within the brain called ventricles.
The brain and nearby structures
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A network of nerves
carries messages back and forth between the brain and the rest of the
body. Some nerves go directly from the brain to the eyes, ears, and
other parts of the head. Other nerves run through the spinal cord to
connect the brain with the other parts of the body. Within the brain
and spinal cord, glial cells
surround nerve cells and
hold them in place.
The brain directs the
things we choose to do (like walking and talking) and the things our body does
without thinking (like breathing). The
brain is also in charge of our senses (sight, hearing, touch, taste, and smell),
memory, emotions, and personality.
The three major parts of the brain control different activities:
Cerebrum—The cerebrum
is the largest part of the brain. It is at the top of the brain. It uses
information from our senses to tell us what is going on around us and tells
our body how to respond. It controls reading, thinking, learning,
speech, and emotions.
The cerebrum is divided into the left and right
cerebral hemispheres,
which control separate activities. The right hemisphere controls the muscles
on the left side of the body. The left hemisphere controls the muscles on
the right side of the body.
Cerebellum—The
cerebellum is under the cerebrum at the back of the
brain. The cerebellum controls balance
and complex actions like walking and talking.
Brain Stem—The brain
stem connects the brain with the spinal cord. It controls hunger and
thirst. It also controls breathing, body temperature, blood pressure, and
other basic body functions.
Major parts of the brain
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