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The Brain: Right down the Middle |
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![]() | Although some people may think that the brain is like a bowl of jell-O, the brain is NOT a bowl of jell-O. Unlike a bowl of jell-O, the brain is not a uniform material. Rather, the brain is made up of many different areas, each having a particular structure and function. To separate the brain into right and left hemispheres, you need to cut the brain in the "midsagittal plane". |
Midsaggital Plane![]() Only some of the structures that are visible on a real brain have been labeled.
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Brain Structures | |
| Cerebral Cortex Functions:
|
The word "cortex" comes from the
Latin word for "bark" (of a tree). This is because the cortex is a sheet
of tissue that makes up the outer layer of the brain. The thickness of
the cerebral cortex varies from 2 to 6 mm. The right and left sides of
the cerebral cortex are connected by a thick band of nerve fibers called
the "corpus
callosum". In higher mammals like humans, the cerebral cortex looks
like it has many bumps and grooves. A bump or bulge on the cortex is
called a gyrus (the plural of the word gyrus is
"gyri") and a groove is called a sulcus (the
plural of the word sulcus is "sulci"). Lower mammals like rats and mice
have very few gyri and sulci. |
| Cerebellum
Functions:
|
The word "cerebellum" comes
from the Latin word for "little brain".
The cerebellum is located behind the brain stem. In some ways, the
cerebellum is a bit like the cerebral cortex: the
cerebellum is divided into hemispheres and has a cortex that surrounds
these hemispheres.
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| Brain stem Functions:
| The brain stem is a
general term for the area of the brain between the thalamus and spinal
cord. Structures within the brain stem include the medulla, pons, tectum,
reticular formation and tegmentum. Some of these areas are responsible
for the most basic functions of life such as breathing, heart rate and
blood pressure. |
| Hypothalamus
Functions:
|
The hypothalamus is composed
of several different areas and is located at the base of the brain. It is
only the size of a pea (about 1/300 of the total brain weight), but it is
responsible for some very important behaviors. One important function of
the hypothalamus is the control of body temperature. The hypothalamus
acts as like a "thermostat" by sensing changes in body temperature and
then sending out signals to adjust the temperature. For example, if you
are too hot, the hypothalamus detects this and then sends out a signal to
expand the capillaries in your skin. This causes blood to be cooled
faster. The hypothalamus also controls the pituitary. |
| Thalamus
Functions:
|
The thalamus receives
sensory information and relays this information
to the cerebral cortex. The cerebral cortex also sends information to the
thalamus which then transmits this information to other areas of the brain
and spinal cord. |
![]() Hear IT! |
Cerebellum | Corpus Callosum | Cortex | Hypothalamus | Thalamus |
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Check out the glossary for definitions of other brain areas.
| BACK TO: | Exploring the Nervous System | Table of Contents |
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