Immunity and immune system

Immunity;

                 Every day we are exposed to large number of infectious agents. However only a few

of  these exposures result in disease. why? This is due to the fact that our body is able defend itself

from most of these foreign agents. This overall ability of the host to fight against the disease causing

organisms, conferred by the immune system is called Immunity.

                        Immunity is of two types ;

•      Innate Immunity;

                          Innate immunity is non-specific type of defence, that is present at the time of birth this is accomplished by providing diffrent types of barriers to the entry of foreign agents into our body the four type of barreirs are :-

1.  physical barriers
   
2.  physiological barriers
   
3.  cellular barriers
   
4.  cytokine barriers

•     Aquired Immunity;

                                 Aquired Immunity, On the Other hand is pathogen specific. It is charecterised by memory. This means that our body when it encounters a pathogen for the first time produces a response called primary respons which is of low intensity. Subsequent encounter with the same pathogen elicits a highly intensified secondary respons this is ascribed tothe fact that our body appears to have memory of the first encounter.

Immune System;

                      The Human immune system consists of lymphoid organ,Tissues,cells and soluble molucule like anti bodies. Immune system is Unique in the sense that it recognises antigens, responds to these and remember them.The immune system also plays an important role in alergic reactions, auto-immune diseases and organ transplantation.