Protect our body: against
microorganisms by preventing
entry and removing them from
Exchange gas: oxygen enters
blood and carbon dioxide
Regulate blood pH: altered by
changing blood carbon
Speak (produce voice):
Movement of air past vocal
folds makes sound and
Smell (olfaction): it occurs
when airborne molecules
are drawn into nasal cavity.
HOW DOES IT WORK?
When we breathe, we inhale (breathe in) oxygen and exhale (breathe
out) carbon dioxide.
This exchange of gases is the respiratory system’s means of getting oxygen to
They are (adult) amphibians, birds, reptiles and mammals (including human
beings) and they breath through lungs.
As you move from amphibians to mammals the surface area of the lungs
increases, that is, they are bigger and bigger.
*Insures a greater amount of gas exchange (or a two way flow of air).
Birds, by contrast, have lungs and air sacs which have only a one-way flow of
This allows for them to have constant contact with fresh air.
This adaptation enables them to fly at high altitudes where there is less
animals, so they
(Inside of the mouth)
(Breathing holes in
(Main organ of the
(Bronchial tube - Airway)
(Small bronchial tube)
(Air sacs in lungs)
(Lining of the lung)
(Flap of cartilage in
EPIGLOTTIS POSITION WHEN FOOD IS
NOT PASSING. IT IS OPEN.
EPIGLOTTIS POSITION WHEN FOOD IS
PASSING. IT IS CLOSED.
The function of the larynx is
to produce sounds (with its
vocal cords) and protect the
trachea against food
The pleura includes two thin
layers of tissue that protect and
cushion the lungs. A liquid,
called pleural fluid, lubricates
the pleural cavity so that the two
layers of pleural tissue can slide
against each other.
During inspiration (when
we breathe in), air passes
through the mouth and nose
down the pharynx (throat)
and through the trachea and
bronchi to the lungs.
In the lungs, air travels
bronchioles which end
in small clusters
(groups) of microscopic
sacs called alveoli.
Oxygen molecules are transformed from the
alveoli into the bloodstream and carbon
dioxide moves out of of the bloodstream and
back into the respiratory track where it is
released through the mouth and nose during
expiration (when we breath out).
The dinosaurs breathed in
the same way that birds do. This
allowed the animal a better use of
the oxygen breathed, which is
estimated between 60 and 65
percent, much higher than the rest
of vertebrates (man takes between
20 and 25 percent of the oxygen
The dinosaurs had air sacs, chambers connected to the lungs, which act as an extension of
these and penetrates the bones lightening their weight. These "bags" serve to store the air, but do
not extract oxygen (function performed by the lungs). We can distinguish between the anterior air
sacs (located in the thoracic cavity) and the posterior air sacs (also called ventral to be located in the
When the dinosaur breathes in, the air is attracted directly from the bronchi to the posterior air sacs,
where the air is stored. When the posterior air sacs expire, they disintegrate, this makes the air pass to the lungs,
where the oxygen is absorbed. The consumed air (which contains carbon dioxide which is detrimental to the
organism) is then lodged in the above air sacs, and the animal inhales fresh air again to be sent to the posterior
air sacs. Then, it expires expelling the air consumed from the previous bags (to the outside) and bringing fresh
air from the posterior air sacs to the lungs.
The air flow is a unidirectional loop, which allows:
1. The lungs are always in contact with fresh air rich in oxygen.
2. There is no gas exchange (oxygen and carbon dioxide) during the breathing process.