Unformatted text preview: Nonspecific Mechanisms of Defense The body possesses many mechanisms that impart nonspecific defense. The objectives of these mechanisms are to prevent microorganisms from gaining a foothold in the body and to destroy them if they penetrate to the deeper tissues. Mechanical barriers. Mechanical barriers at the portal of entry represent the first line of defense for the body. These defenses are normally part of the body's anatomy and physiology. The skin is a representative example. The outermost layers of skin consist of compacted, cemented cells impregnated with the insoluble protein keratin. The thick top layer is impervious to infection and water. In the unbroken state, it usually is not penetrated by pathogens. The mucous membranes of the urinary, respiratory, and digestive tracts are another example. They are moist and permeable, but their fluids, such as tears, mucus, and saliva, rid the membrane of...
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- Fall '07
- respiratory tract, Nonspecific Chemical Defenses, appropriate receptor sites, caustic hydrochloric acid, flushing action. Cilia, barriers. Mechanical barriers