Much of the brain's physiological task involves receiving information from
the rest of the body, interpreting that information, and then guiding the
body's response to it. Types of input the brain interprets include odors,
light, sounds, and pain. The brain also helps perform vital operations such as
breathing, maintaining blood pressure, and releasing hormones (chemical signals
that control certain cells and organs).
The brain is divided into sections. These sections include the cerebrum, the cerebellum, the diencephalon, and the brainstem.
Each of these parts is responsible for certain portions of the brain's overall
job. The larger parts are, in turn, divided into smaller areas that handle
smaller portions of the work. Different areas often share responsibility for
the same task.
The cerebrum is the largest part of the brain. It is
responsible for memory, speech, the senses, emotional response, and more. It is
divided into several sections called lobes. These lobes are referred to as the
frontal, temporal, parietal, and occipital; each handles a specific segment of
the cerebrum's jobs.
The cerebellum is below and behind the cerebrum and is
attached to the brain stem. It controls motor function, the body's ability to
balance, and its ability to interpret information sent to the brain by the
eyes, ears, and other sensory organs.
The functions the brain stem governs include respiration, blood pressure,
some reflexes, and the changes that happen in the body during what is called
the “fight or flight” response. The brain stem is also divided into several
distinct sections: the midbrain, pons,
and medulla oblongata.
The diencephalon is inside the cerebrum above the brain
stem. Its tasks include sensory function, food intake control, and the body's
sleep cycle. As with the other parts of the brain, it is divided into sections.
These include the thalamus, hypothalamus, and epithalamus.
The brain is protected from damage by several layers of defenses. Outermost
are the bones of the skull. Beneath the skull are the meninges, a series of
sturdy membranes that surround the brain and spinal cord. Inside the meninges,
the brain is cushioned by fluid.
Still, the brain can suffer damage, become diseased,
or malfunction. These problems may include cancer, physical injuries such as
skull fractures, and ruptures of blood vessels that supply the brain.