IMMUNITY Definition: Ability of the body to fight against any foreign agent that could be harmful to the body in order to protect body from any harm. Immunity is majorly provided by different body barriers like skin, mucous membranes and the body fluids like blood and lymph. Different organs and tissues also play a major roll in provision of immunity like lymph nodes, spleen, thymus and bone marrow. Now if we discuss immunity on the basses of provision by different organs it would be divided under to major terms: Innate immunity Acquired immunity Innate immunity This is the type of immunity that you have by birth, and it also keeps you alive just after your birth. Without this immunity you can't survive no matter how much heroic measures are taken. And it is provided by, Physical barriers: Skin and Mucous membranes lining different body openings. How? All the epithelia that are exposed to the external environment like skin and muco...