WORKING OF THE
HUMAN BRAIN
BIOLOGY
HOW DOES THE BRAIN WORK?
• The Brain works like a big computer. It processes information that it receives
from the senses and body, and sends messages back to the body. But the
brain can do much more than a machine can: We think and experience
emotions with our brain, and it is the root of human intelligence.
• The root of human intelligen human brain is roughly the size of two clenched
fists and weighs about 1.5 kilograms. From the outside it looks a bit like a
large walnut, with folds and crevices. Brain tissue is made up of about 100
billion nerve cells (neurons) and one trillion supporting cells that stabilize
the tissue.
THE BRAIN IS MADE UP OF VARIOUS PARTS, EACH WITH ITS OWN FUNCTIONS:
•
• The cerebrum the diencephalon – including the thalamus,
hypothalamus and pituitary gland the brain stem – including
the midbrain, pons and medulla
• The cerebellum
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•
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VARIOUS PARTS OF THE
BRAIN
THE FUNCTIONS OF THE BRAIN
• The cerebrum has a right half and a left half, known as the right and left hemispheres.
The two hemispheres are connected via a thick bundle of nervefibers called the
corpus callosum. Each hemisphere is made up of six areas (lobes) that have
different functions. The cerebrum controls movement and processes sensory
information. Conscious and unconscious actions and feelings are produced here. It
is also responsible for speech, hearing, intelligence and memory.
•
• The functions of the two hemispheres are mostly different:
While the left hemisphere is responsible for speech and
abstract thinking in most people, the right hemisphere is
usually responsible for spatial thinking or visualization. The
right side of the brain controls the left side of the body, and
the left side of the brain controls the right side of the body.
This means that damage to the left hemisphere due to a
stroke, for example, can lead to paralysis on the right side
of the body.
• The left cerebral cortex is responsible for speech and
language. The right cerebral cortex supplies spatial
information, such as where your foot is at the moment.
The thalamus gives the cerebrum sensory information
from the skin, eyes and ears, as well as other information.
The hypothalamus regulates things like hunger, thirst and
sleep. Together with the pituitary gland, it also regulates
the balance of hormones in your body.
• The brain stem relays information between the brain, the
cerebellum and the spinal cord, as well as controlling eye
movements and facial expressions. It also regulates vital
functions like breathing, blood pressure and heartbeat.
• The cerebellum coordinates movements and is responsible
HOW IS THE BRAIN SUPPLIED
WITH BLOOD?
The brain needs a steady flow of enough oxygen, glucose, and other nutrients. For that reason,
it has a particularly good blood supply. Each side of the brain receives blood through three
arteries:
• In the front, the anterior cerebral artery supplies the tissue behind the forehead and under
the crown (the top of the head).
• The middle cerebral artery is important for the sides and areas
that are further inside the brain. The anterior and middle
cerebral artery split off from the internal carotid artery (a major
blood vessel in the neck).
• The posterior cerebral artery supplies the back of the head, the lower part of the brain,
and the cerebellum. It is supplied with blood from the vertebral arteries, which are
also major blood vessels in the
• Before the three arteries reach “their” brain region, where
they split into smaller branches, they are close together
below the brain. In this area, they are connected to each
other by smaller blood vessels – forming a structure similar
to a traffic circle. There are connections between the
arteries in other areas of the brain too. The advantage of
these connections is that they can partly make up for blood
supply problems in the brain: For example, if a branch of an
artery gradually becomes narrower, blood can still flow to
the part of the brain it supplies through these alternative
routes (collateral blood flow).
• The smallest branches (capillaries) of the arteries in
the brain supply the brain cells with oxygen and
nutrients from the blood – but they do not let other
substances pass as easily as similar capillaries in the
rest of the body do. The medical term for this
phenomenon is the “blood-brain barrier.” It can
protect
• After thepassed
oxygen has sensitive brain
into the cells, from toxic
the oxygen-poor substances
blood flows away throughinthe
veins of the brain (cerebral veins). The veins carry the blood to larger blood vessels
the blood, for instance.
known as sinuses. The sinus walls are strengthened by a tough membrane (dura
mater), which helps them keep their shape too. This keeps them permanently open
and makes it easy for the blood to flow into the veins in the neck.
• PPT made by:
• Name: Arpita Rajendra Shivtare
• Class: 10th Div: A(Louis Pasture)
• Roll no. 4
THANK YOU
