802
UNIT 4
Maintenance of the Body
22
and fourth processes also occur. As you can see, the respiratory and
circulatory systems are closely coupled, and if either system fails,
the body’s cells begin to die from oxygen starvation.
Te actual use of oxygen and production of carbon dioxide
by tissue cells, known as cellular respiration, is the cornerstone
of all energy-producing chemical reactions in the body. We dis-
cuss
cellular respiration
, which is not a function of the respira-
tory system, in the metabolism section of Chapter 24.
Because it moves air, the respiratory system is also involved
with the sense of smell and with speech.
Functional Anatomy
of the Respiratory System
Identify the organs forming the respiratory passageway(s)
in descending order until you reach the alveoli.
Describe the location, structure, and function of each of the
following: nose, paranasal sinuses, pharynx, and larynx.
List and describe several protective mechanisms of the
respiratory system.
Te major function of the
respiratory system
is to supply the
body with oxygen and dispose of carbon dioxide. ±o accomplish
this function, at least four processes, collectively called
respira-
tion
, must happen:
1.
Pulmonary ventilation
(commonly called breathing): Air
is moved into and out of the lungs (during
inspiration
and
expiration
) so the gases there are continuously changed
and refreshed.
2.
External respiration:
Oxygen diffuses from the lungs to
the blood, and carbon dioxide diffuses from the blood to
the lungs.
3.
Transport of respiratory gases:
Oxygen is transported
from the lungs to the tissue cells of the body, and carbon
dioxide is transported from the tissue cells to the lungs.
Te cardiovascular system accomplishes this transport us-
ing blood as the transporting fluid.
4.
Internal respiration:
Oxygen diffuses from blood to tissue
cells, and carbon dioxide diffuses from tissue cells to blood.
Te respiratory system is responsible for only the first two pro-
cesses
(Figure 22.1)
, but it cannot accomplish its primary goal of
obtaining oxygen and eliminating carbon dioxide unless the third
Nasal cavity
Trachea
Carina of
trachea
Left main
(primary)
bronchus
Right main
(primary)
bronchus
Right lung
Left lung
Nostril
Oral cavity
Pharynx
Larynx
Diaphragm
Figure 22.1
The major respiratory organs in relation to surrounding structures.
previous page 836 Human Anatomy and Physiology (9th ed ) 2012 read online next page 838 Human Anatomy and Physiology (9th ed ) 2012 read online Home Toggle text on/off