The immune system is a versatile defence system that has evolved to protect animals from invading pathogenic microorganisms. It generates an enormous variety of cells and molecules capable of specifically recognizing and eliminating an apparently limitless variety of foreign invaders. The immune system is highly specific.
In present time it can be clearly noticed that every individual generally falls the victim of many viruses and infectious diseases. But whatever is the case, if we donnot take any medicine we can observe that after two days or a week some of the viral infection itself gets vanish away or get completely cured with time. Suppose we had a cut in our hand, after some days the wound itself gets healed.
Have you ever…show more content… K. Abbas, A. H. Licthman & S. Pillai(pg19,2007); Innate immunity is the first defence against infections. The mechanisms of innate immunity exist before encounter with microbes and are rapidly activated by microbes before the development of adaptive immune responses. Innate immunity is also the phylogenetically oldest mechanism of defence against microbes and co-evolved along with microbes to protect all multicellular organisms, including plants and insects, from infections. Adaptive immunity mediated by T and B lymphocytes appeared in jawed vertebrates and is superimposed on innate immunity to improve host defence against microbes.
Innate immunity serves to two important functions. It is the initial response to microbes that prevent, control, or eliminate infections of the host and to microbes stimulates adaptive immune response and can influence the nature of the adaptive response to make them optimally effective against different types of microbes.
Some components of innate immunity are functioning at all times, even before infection; these components include barriers to microbial entry provided by epithelial surfaces, such as the skin and the lining of the gastrointestinal and respiratory tracts. Other components of innate immunity are normally inactive but poised to respond rapidly to the presence of microbes; these components include phagocytes and the complement