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Unit 19: Biology Part 2 Page 59 of 137
Figure 39 – Air breathed in
eventually leads to the alveoli Figure 40 – In each alveolus
in the lungs. (that’s the singular form of
alveoli) oxygen flows into the
Alveoli are small sacs at the end of blood while carbon dioxide
bronchioles that look sort of like a flows out.
bunch of grapes. These sacs are
the places where gas exchange How We Breathe
takes place.
We usually breathe without
Gas exchange means that, in the thinking about it, which is a good
alveoli, oxygen moves into the thing. Imagine if you had to stop
blood so it can be taken all over and think about it each time you
the body, and carbon dioxide had to breathe. You wouldn’t be
crosses from the blood back to the able to do anything else! If you’ve
alveoli so it can be breathed out. ever gone swimming, done yoga,
or sung, however, you know that it
is possible to control when you
breathe.
Earlier, we talked about how the
diaphragm is important for
breathing in and out, but how does
it work exactly? To understand
this, you have to understand
something about pressure.
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