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This is the ability of an organism to resist 1 by 2 and destroying foreign 3 or organisms. Although all 4 have some immune capabilities, little is known about 5 immunity. Mammals are protected by a variety of preventive mechanisms, some of them 6 (e.g., barriers, such as the 7 ), others highly 8 (e.g., the response of 9 ).
2. Nonspecific DefencesThese include physical and 10 barriers, the 11 response, and 12 . Physical barriers include the 13 skin and 14 membranes. These barriers are aided by various 15 chemicals in 16 and fluids. An example of such a substance is 17 , an 18 present in 19 that destroys the cell membranes of certain 20 .