TY - CHAP M1 - Book, Section TI - Lung Infections: An Overview A1 - Manian, Prasad A2 - Sugarbaker, David J. A2 - Bueno, Raphael A2 - Burt, Bryan M. A2 - Groth, Shawn S. A2 - Loor, Gabriel A2 - Wolf, Andrea S. A2 - Williams, Marcia A2 - Adams, Ann PY - 2020 T2 - Sugarbaker’s Adult Chest Surgery, 3e AB - The respiratory tract is in constant contact with the environment and exposed to direct inoculation by infectious agents. Various defense mechanisms exist to prevent infections. Anatomic barriers represent the first line of defense. Large (>5 µm) airborne particles are trapped by the nasal cilia. Intermediate (1–5 µm) particles are deposited in the trachea and bronchi, and small (0.01–1 µm) particles are deposited in the bronchioles and alveolar spaces. The respiratory tract from the trachea to the bronchioles is lined with ciliary cells and with goblet cells that secrete a thin layer of mucus. The rhythmic beat of the cilia moves the mucus-trapped material upward, which is then cleared externally by the cough mechanism or swallowed interiorly and eliminated by the gastrointestinal tract. This mechanism is called the mucociliary escalator (Fig. 106-1). SN - PB - McGraw-Hill Education CY - New York, NY Y2 - 2024/04/20 UR - accesssurgery.mhmedical.com/content.aspx?aid=1170412884 ER -