Page 682 - Atlas of Histology with Functional Correlations

FIGURE 17.19 ■ A low-power ultrastructure of the lung, showing a portion of a

bronchiole wall and adjacent alveoli. ×1,500.

From: Gartner LP, Hiatt JM. BRS Cell Biology & Histology. 6th ed. Baltimore: Lippincott
Williams & Wilkins, 2011.

FUNCTIONAL CORRELATIONS 17.3 ■ Cells in

Lung

Respiratory System—Conducting Portion

The conducting portions of the respiratory system condition the inhaled
air. Mucus that is produced by goblet cells in the pseudostratified ciliated
respiratory epithelium and mucous glands in the lamina propria contain

antimicrobial substances. The goblet cells and serous secretions from serous
glands contain immunoglobulins, lysozymes, and enzymes that destroy
bacteria. These secretions form the airway mucus layer that covers the
luminal surfaces in conducting tubes. As a result, the moist mucosa in the

conducting airways humidifies the air. The mucus and ciliated epithelium
also filter and clean the air of particulate matter, infectious microorganisms,
and other airborne matter. These secretions are moved toward the pharynx by
the motility of cilia where they are either swallowed or expelled. In addition,

an extensive capillary network beneath the epithelium in the lamina propria
warms the inspired air in the conducting portion before it reaches the
respiratory portion in the lungs.

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