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Control of
Respiratory
Function
Structural Organization of the Respiratory System
Conducting Airways
Nasopharyngeal Airways
Laryngotracheal Airways
Tracheobronchial Airways
Lungs and Respiratory Airways
Pleura
Respiratory Lobules
Pulmonary and Bronchial Circulations
Innervation
Exchange of Gases Between the Atmosphere and the
Lungs
Basic Properties of Gases
Pulmonary Ventilation
Respiratory Pressures
Chest Cage and Respiratory Muscles
Lung Compliance
Airway Resistance
Lung Volumes and Pulmonary Function Studies
Efficiency and Work of Breathing
Exchange of Gases Within the Lungs
Alveolar Ventilation
Distribution of Alveolar Ventilation
Dead Air Space
Perfusion
Distribution of Pulmonary Blood Flow
Shunt
Mismatching of Ventilation and Perfusion
Diffusion
Oxygen and Carbon Dioxide Transport
Oxygen Transport
Hemoglobin Transport
Plasma Transport
Oxygen–Hemoglobin Dissociation Curve
Carbon Dioxide Transport
Control of Breathing
Respiratory Center
Regulation of Breathing
Chemoreceptors
Lung and Chest Wall Receptors
Voluntary Regulation of Ventilation
Cough Reflex
Dyspnea
Respiratory
Function
6
U N I T
21
C h a p t e r
he primary function of the respiratory system is gas
exchange, with oxygen from the air being trans-
ferred to the blood and carbon dioxide from the blood
being eliminated into the atmosphere. In addition to
gas exchange, the lungs serve as a host defense by pro-
viding a barrier between the external environment and
the inside of the body. And finally, the lungs are meta-
bolic organs that synthesize and break down different
substances.
The content in this chapter focuses on the structure
and function of the respiratory system as it relates to
the exchange of gases. The function of the red cell in the
transport of oxygen is discussed in Chapter 13.
Structural Organization of the
Respiratory System
The respiratory system consists of the air passages, the
two lungs and the blood vessels that supply them, and
the respiratory muscles involved in moving air into and
out of the lungs. Functionally, the respiratory system
can be divided into two parts: the
conducting airways
,
through which air moves as it passes between the atmo-
sphere and the lungs, and the
respiratory airways
of the
lungs, where gas exchange takes place.
The lungs are soft, spongy, cone-shaped organs
located side by side in the chest cavity (Fig. 21-1). They
are separated from each other by the
mediastinum
(i.e.,
the space between the lungs) and its contents—the heart,
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