Download The Heart - 3F-Int1

Heart & Blood
By Loren
The Heart
• An adult heart is about
the size of a small fist
and has a mass of 200400 grams. It sits almost
in the centre of the
chest, between the two
lungs and is tipped
slightly to the left. It is
well-protected by the
bones of the ribcage,
breastbone and the
spine.
Inside the heart
• Inside the heart there are
four spaces called cambers.
A thick wall, separates the
two sides of the heart. Each
side has a upper chamber
and a lower chamber. Blood
flows into the heart through
the atria and leaves through
the ventricles. The walls of
the ventricles are thinner
because they have to work
harder to pump blood out of
the heart and into the
arteries.
Heartbeat
• Cardiac muscle is able
to beat all the time,
whether you are awake
or asleep. It is called an
involuntary muscle it
beats without you ever
to think about it. An
adults heart will beat
approximately 70 times
every minute.
Blood vessels
• Arteries carry blood away
from the heart to the rest of
the body. They have a very
strong muscular wall to
withstand the high pressure
of the blood as it is pumped
out of the heart. Veins carry
blood back to the heart.
They have thinner walls
than arteries because they
carry blood at a lower
pressure.
Capillaries
• Capillaries are very fine,
narrow vessels, and they
occur in branching
networks throughout
body tissues. Capillary
walls are made of just a
single layer of cells.
Healthy Heart
• The heart affects every
aspect of our lives. It
must work efficiently if
we are to stay fit and
healthy. Exercise is very
important, the heart is a
muscle and like any
other muscle the more it
is used the stronger it
becomes.
Heart Attack
• The heart muscle needs
a constant supply of
blood to enable it to
function and stay
healthy. The most
common cause of a
heart attack is blockage
of the coronary arteries
by a build up of fatty
deposits or by a blood
clot.
Avoiding heart attacks
• After suffering a heart
attack, many patients
are advised to alter their
lifestyle. Heart attacks
are more common in
people who:
• Eat a lot of fatty foods
• Are overweight
• Take little exercise
• Suffer a lot of stress
Blood
• Blood is a liquid
containing millions of
red blood cells that
make it look red. It also
contains millions of
white blood cells. Blood
has three main
functions-Transport,
regulation and
protection.
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