It is the respiratory system
that enables our bodies to breathe in oxygen and breathe out carbon
dioxide. Without oxygen, we cannot live for more than a few
minutes. All the cells in the body use oxygen to aid in the process of
converting food into energy.
The process by which we breathe is as
follows. Oxygen is taken in through the nose (nasal cavity).
Oxygen is a component of air. From the nose the air enters the pharynx
(the throat cavity behind the mouth). From there the air passes through
the voice box or larynx and then into the windpipe or trachea which is
supported by stiff cartilage rings that one can feel at the throat. The
trachea becomes divided at the lower end into two tubes, called bronchi
(bronchus - singular). Within these pathways, air is warmed, filtered,
moistened, and delivered to and from the lungs. Each bronchus enters a lung (left and
right) and divide up into narrower tubes called the bronchioles. At the
end of these tiny tubes are hundreds of tiny air sacs called alveoli
(alveolus-singular). These tiny air sacs in the lungs hold the air for a
few seconds until
the oxygen is diffused into the blood through capillaries. Blood
returning from the heart carries carbon dioxide which leaves the blood stream
by diffusing into the air sacs which is then exhaled out by the lungs.
- Provide students with copy of worksheets.
- Go over each of the words on their worksheet.
- Repeat the section above on how we take in air through our
lungs. Have the students label the parts of the respiratory system
as you talk. Give them clues on where each part belongs.