ABSTRACT
Airways The airways consist of a series of passages for airflow that become progressively smaller and more numerous while branching into the different areas of the lung. This progressive narrowing and branching of the airways is known also as arborization, and is demonstrated in Figure 6-1.1
AIRWAY ZONES The respiratory system begins with the nostrils and the mouth, both of which conduct air into the larynx and trachea. The nose plays an important role as it allows inhaled air to become warm, clean, and moist, and prevents crusting of lung tissue and infection. This system of filtration is bypassed in patients with tracheostomies or
mainstem bronchi, both of which are divided at a bifurcation known as the carina, and further subdivided into smaller bronchi, bronchioles, and ultimately, into small air sacs known as alveoli. Since the air passing through the larger airways (e.g., trachea, bronchi) is not exchanged with tissues, these airways are defined collectively as the conducting zone. Once air reaches the terminal airways (e.g., bronchioles and alveoli), oxygen and carbon dioxide is being exchanged; this area of the lung is defined as the respiratory zone.
