Mucociliary clearance

Mucociliary clearance is the airway’s transport of mucus and trapped particles toward the throat through coordinated ciliary beating. It is a primary defense against inhaled pathogens and debris.

Ciliary beating: The coordinated bending cycle by which motile cilia generate directional fluid movement. Repeated ciliary strokes propel the mucus layer toward the throat.
Airway epithelium: The cellular lining of the respiratory tract that separates airway contents from underlying tissues. Ciliated epithelial cells form the surface on which clearance takes place.
Primary ciliary dyskinesia: An inherited disorder in which defective motile cilia impair mucociliary transport and other cilia-dependent functions. It provides a direct example of how impaired ciliary motion disrupts airway clearance.
Alveolar macrophage: A resident immune cell in the lung alveoli that engulfs particles and microbes. Macrophages handle material reaching alveoli, beyond the main ciliated airway surface.
Airway surface liquid: The thin fluid layer covering airway surfaces, including a watery periciliary layer beneath mucus. Its depth and composition let cilia beat without becoming compressed by mucus.
Goblet cell: A mucus-secreting epithelial cell found in mucosal linings, including the airways. Goblet cells contribute mucus that captures inhaled material.
Cystic fibrosis: An inherited disease caused by pathogenic variants in CFTR, affecting salt and water transport across epithelia. Abnormal airway surface hydration contributes to thick secretions and impaired clearance.
Sneezing: A reflexive expulsion of air through the nose and mouth, triggered by nasal irritation. Sneezing rapidly expels nasal irritants rather than continuously transporting airway mucus.
Mucus: A hydrated gel of mucins and other substances that traps particles and microbes on epithelial surfaces. Its properties determine how well trapped material can be transported by cilia.
Submucosal gland: A gland beneath a mucosal surface that releases secretions through ducts. Airway glands add mucus and fluid to the material cleared by cilia.

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