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Finally, let's talk about the final learning
objective. How does the cardiovascular system
work? Well here we see a diagram that shows
you in picture form all the functions of a
cardiovascular system. We have already mentioned
them as we have gone along here. Of course
essential to the entire system is the heart
pumping the blood. The arteries, seen on the
left with a red line in the channel, transport
the red blood which is full of oxygen away
from the heart. As we have said, the arteries
divide eventually arriving in the arterioles,
the resistance factor in the cardiovascular
system and from there into the capillaries.
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Notice how thin walled they are. So that only
one red blood cell at a time can get through.
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This small size allows the red blood cells
to release their oxygen, to pick up carbon
dioxide, waste product from the cells, and
then to pass into the little tiny veins, the venules
and then into larger veins, you can see on
the right hand side of the diagram, the blue arrow,
showing the veins carrying the blood back
to the right side of the heart, where it will
be transported into the lungs to give off
carbon dioxide, take on oxygen, and then
eventually make their way back to the left side
of the heart as red blood to be pumped out
to the body again in a never ending circle.