Since the wall of the thorax is reinforced by muscles, bones, and cartilages, we
can consider the thorax to be a "
r" filled with gas.
The abdominopelvic cavity is filled with a f
m, the water of the
Breathing is the process of
ing air into and out of the
Breathing involves the pressure gradient between the surrounding at
c cavity. Since atmospheric pressure is relatively constant, breathing
depends upon changing the pressure within the t
The lungs have a certain total volume called the
is a certain portion of air always present in the lungs, called the r
one inhales as much air as possible and then exhales as much as possible, the volume
exhaled is called the
The breathing cycle includes an i
n, and then a
period. The rate of respiration is the number of breathing
. The amount of air exchanged in a given period depends upon the
h of breathing, which are adjusted according to physiological
In ordinary, low-level activity, the breathing cycles are of the
Occasionally, there will be a breathing cycle with a slightly greater volume exchange,
The volumes of air exchanged are much greater in
d breathing. The
volume depends upon the
If one makes an exhalation effort but still holds the air inside the lungs, it is called
's maneuver. If one suddenly releases the air, the result is a
Costal breathing is accomplished by moving the r
e as a whole.
In costal inhalation, the lungs are expanded and inflated with air as a result of the
d movement of the rib cage.
The "bucket handle" effect increases the
e diameter of the rib cage. The
second type of movement increases the
r diameter of the rib cage.