Our Lungs and How They Work
Aside from the obvious, that we need lungs to breathe, most people know very little about these
organs that are vital to our well being and survival.
Our lungs are located in our thorax and are so large they occupy the entire space of our chest. They are located
and protected by our ribs, which are connected to our spine. Our rib muscles move upwards and outwards to give our
lungs more space as we inhale and they expand.
We have two lungs, although they are not the same size. Our left lung is slightly smaller that our right one and
this size difference provides more space for our heart.
They are made from an elastic and spongy tissue that contracts and expands in accordance to our breathing. As it
expands the air pressure within the lungs is lower than the external air pressure and this allows air to enter
through the air passages, inflating the lungs.
As you exhale, the diaphragm and intercostal muscles relax and the chest cavity is reduced. The reduction in the
volume of the cavity makes the air pressure within the chest cavity to be higher than the external air pressure.
The result is that the air in the lungs (high pressure) flow out of the air passages to the outside air (whose
pressure is lower). This cycle is repeated every time we breathe. In with the good air, out with the bad air.
What Happens As We Inhale:
As you inhale air through the mouth or nose (inhale), the air passes through the windpipe and inwards. Along the
way we have small hairs called cilia that move gently to keep mucus and dirt out of the lungs. One of the effects
of smoking is damage to these very fine hairs.
We have two tubes called bronchi that come out of our trachea, one for each lung, and these in turn branch out
into smaller tubes called bronchiole. We have approximately 30,000 bronchiole in each lung. Each bronchiole is as
thin as a hair. At the end of each bronchiole is a special area that leads to a mass of tiny sacs called alveoli.
There are approximately 600 million alveoli in the lungs. The alveoli are covered by thin capillaries. These
capillaries are so small that blood cells have to form in single file to pass through them.
The alveoli allow oxygen to pass from air to blood. All body cells need oxygen continuously. Oxygen passes
through the walls of each alveolus into the tiny capillaries that surround them. Oxygen enters the blood in the
capillaries, traveling on red blood cells, through layers of blood vessels to the heart. The heart sends the
oxygenated blood (filled with oxygen) to all body cells.
What Happens When We Exhale
As you breathe out, everything happens in reverse order: The diaphragm relaxes and moves upward, pushing the air
out of the lungs. The rib muscles relax and the ribs move in again, creating a small space in the chest.
It here that our cells have taken the oxygen they need and so our blood carries back carbon dioxide and other
waste that must be removed from the body. (Again, in with the good air and out with the bad air).
The lungs are covered by two special layers called pleural membranes. These membranes are separated by a fluid
that allows them to easily slide around as you inhale and exhale.
Whenever we are breathing, talking, singing or crying, it s our lungs that are working. We cannot survive more
than a few minutes without breathing as our oxygen starved cells begin to die. Our lungs and brain work together to
help you inhale and exhale. This means we do not have to make a conscious decision to breathe and our air
requirements, for example as we exercise or sleep, are coordinated automatically.
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