| |
How the lungs work
The human body has two lungs, one on the left side of the chest
and one on the right. Each lung is divided into sections called
lobes. The right lung has three lobes. The left lung, smaller because
it shares cavity space with the heart, has only two lobes.
The body’s cells and organs require oxygen to function and
sustain life. With every intake of breath, fresh air brings in new
oxygen and with every exhale, “used” or waste breath
is sent out of the body in the form of carbon dioxide.
The respiratory system is made up of a complex network of larger-to-smaller
airways. Breath coming in through the mouth and nose proceeds down
the largest airway (trachea). The trachea splits into two smaller
“pipes” called the bronchi. These proceed to the right
and left lungs by means of much smaller tubes called bronchioles,
which in turn branch out to clusters of millions of tiny air sacs.
These air sacs (alveoli), shaped like folded balloons, have thin,
delicate walls that contain tiny blood vessels called capillaries.
Capillaries allow oxygen to pass directly through them and into
the bloodstream as the air sacs expand and contract. Capillaries
also release carbon dioxide, a by-product of bodily processes, into
the lungs to be exhaled.
The heart and lungs work together in moving oxygen to all the cells
of the body. Blood that has been oxygenated in the lungs moves through
the pulmonary vein in the lungs through the left side of the heart
where it is pumped to the rest of the body. Similarly, blood that
has little oxygen left and is rich in carbon dioxide goes back to
the right side of the heart through two large veins where is it
pumped back to the lungs. There it is replenished with oxygen and
carbon dioxide is released.
There are dozens of different types of cells at work in the lungs,
each playing its own non-stop role as a person breathes in and out
during the course of a lifetime. In the constant exchange of oxygen
and carbon dioxide, between six and ten liters of inhaled air every
sixty seconds are transferred into the lungs. Oxygen travels from
the air sacs to the blood at the rate of a third of a liter per
minute.
|
|
|
