Page 63 - Science Class 07
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conscious of your breathing. When you
exercise, you need to move more air. To do this,
you can take bigger breaths or breathe more
Your le and right lungs aren’t exactly the
quickly – usually both.
same. The lung on the le side of your body
is divided into two lobes. The lung on your Although breathing is usually automa c, you
right side is divided into three. The le lung can control it if you want to when you talk
is also slightly smaller, allowing room for or sing.
your heart. RESPIRATION
How Do you Breathe? Respira on is a chemical process in which food
Healthy lung ssue is springy or elas c so your breaks down into simpler substances and
muscles need to work to expand your chest releases energy essen al for life. Respira on
and draw air into your lungs. takes place inside the cells of the body. Most
organisms require a constant supply of oxygen
Signals from the respiratory centre in your
to respire. When this oxygen reaches the cells it
brain travel down nerves to your diaphragm
combines with glucose, sugar into which food
and other muscles. The diaphragm is pulled has been converted, energy is released
flat, pushing out the lower ribcage and
together with the waste products of carbon
abdomen. At the same me, the muscles
dioxide and water.
between your ribs pull your rib cage up and
out. This expands the chest and draws air into C H O + 6O 6H O + 6CO + Energy
2
2
2
6
6
12
the lungs. (glucose) (oxygen) (water) (carbon dioxide)
Air is pulled into your nose or mouth and into TYPES OF RESPIRATION
your windpipe. This divides into airways You already know that all the living oganisms
supplying the le and right lungs. respire to survive. They need air for respira on.
The air passes down the airways, which divide But there are certain ny organisms that do not
another 15 to 25 mes and finally into need air to release energy.
thousands of smaller airways un l the air On this basis, we can categorise respira on into
reaches the air sacs. two types:
When you Breathe Out? v Aerobic Respira on
At rest, breathing out is mostly a passive v Anaerobic Respira on
process. The muscles you use to breathe in Aerobic Respira on
now relax and your elas c lungs push the air
The respira on that takes place in the presence
out. When you exercise and your body needs
of oxygen is called aerobic respira on because
to move air more quickly, your abdominal
it uses ‘air’ which contains oxygen. The aerobic
muscles provide the main drive for exhaling.
respira on involves u lisa on of oxygen for the
Intercostal muscles also help.
breakdown of chemical bonds in glucose to
The system works so that you breathe in and release energy in high amounts. It is the chief
out comfortably at rest where the least effort is source of energy for plants and animals.
required to move air – and you’re probably not Animals and plants that use oxygen for
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