Innate Immune System - Anatomical Barriers

Anatomical Barriers

Anatomical barrier Additional defense mechanisms
Skin Sweat, desquamation, flushing, organic acids
Gastrointestinal tract Peristalsis, gastric acid, bile acids, digestive enzyme,
flushing, thiocyanate, defensins, gut flora
Respiratory airways and lungs Mucociliary elevator, surfactant, defensins
Nasopharynx Mucus, saliva, lysozyme
Eyes Tears

The epithelial surfaces form a physical barrier that is very impermeable to most infectious agents, acting as the first line of defense against invading organisms. Desquamation of skin epithelium also helps remove bacteria and other infectious agents that have adhered to the epithelial surfaces. In the gastrointestinal and respiratory tract, movement due to peristalsis or cilia helps remove infectious agents. Also, mucus traps infectious agents. The gut flora can prevent the colonization of pathogenic bacteria by secreting toxic substances or by competing with pathogenic bacteria for nutrients or attachment to cell surfaces. The flushing action of tears and saliva helps prevent infection of the eyes and mouth.

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Famous quotes containing the word barriers:

    The majority of women, they have half-a-glass too much and let down their barriers a little. Then they wake up in the morning, riddled with guilt and think they can reclaim their virtue by saying, “I don’t remember.”
    Blake Edwards (b. 1922)