Changes

*Prevents dessication of the mucosal epithelium

*Prevents dessication of the mucosal epithelium

*Contains antimicrobial substances

*Contains antimicrobial substances

*Immunoglobulin - IgA

*Immunoglobulin - [[IgA]]

**IgA produced by mucosal plasma cells

**[[IgA]] produced by mucosal plasma cells

**IgA can attach to specific pathogen antigens (viruses, bacteria) trapping them in the mucus for clearance

**[[IgA]] can attach to specific pathogen antigens (viruses, bacteria) trapping them in the mucus for clearance

*Lysosyme

*Lysosyme

**Direct action on bacterial cell walls

**Direct action on bacterial cell walls

*This mucous blanket is contributed to by the secretions of the Clara cells in the terminal and respiratory bronchioles

*This mucous blanket is contributed to by the secretions of the Clara cells in the terminal and respiratory bronchioles

*Also contained in these secretions in the respiratory tract are: IgA, IgG, and Interferon

*Also contained in these secretions in the respiratory tract are: [[IgA]], IgG, and Interferon

*At all levels of the tract, and especially at bifurcations, there are subepithelial leukocytes which have the potential to develop into lymphoid follicles under a persistent antigenic challenge

*At all levels of the tract, and especially at bifurcations, there are subepithelial leukocytes which have the potential to develop into lymphoid follicles under a persistent antigenic challenge