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The composition of the immune defense lineBody
The composition of the immune defense lineBody a total of three lines of defense:The first line of defenseBy the skin and mucous membranes, they can not only block the pathogen invades the human body, and their secretions (such as lactic acid, fatty acid, stomach acid and enzymes), the role of sterilization. Ciliated respiratory mucosa, and can remove foreign bodies.The second line of defenseBactericidal substances in the body fluids and phagocytic cells, these two lines of defense is a natural defense function, gradually built up by mankind in the evolutionary process is characterized by human beings are born there, not for a certain kind of specific pathogens, a variety of pathogens are defensive role, so called non-specific immunity (also known as innate immunity) In most cases, these two lines of defense to prevent the invasion of pathogens to the body.The third line of defenseThe third line of defense of immunity: specific immunity. Mainly by the immune organs (thymus, lymph nodes and spleen, etc.) and immune cells (lymphocytes), lymphatic B-cell responsible for humoral immunity; lymphoid T cells responsible for cellular immunity. (Cellular immunity often end up also need to humoral immune to the aftermath), the third line of defense is gradually built up by the body after birth acquired defensive function, the feature is generated after the birth, only works against a particular pathogen or foreign body thus called specific immunity (also known as acquired immune). The specificity of the acquired immune system, is a specific immune mechanism against an antigen generated by immune lymphocytes (plasma cells) secrete antibodies, only play on the same antigen immune function. There is no variation or other antigens. 1st and 2nd line of defense, like the body of the anti-virus software; 3 line of defense designed to kill the software like a virus / trojan. Only three lines of defense at the same time, a complete, well-play the immune function, our health can be more fully guaranteed.
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