And that basically initiates many different types of mechanisms that eventually protect our body from different types of pathogenic agents and antigens. Now, what about the alternative pathway? Well, unlike the classical pathway, which needs the presence of our antibody antigen complex to initiate, the alternative pathway can be triggered even in the absence of the antibody antigen complex. The question is how? Well, it turns out that one of the major agents, one of the major proteins in the complement system we call C Three, does not actually need something to activate itself so it can spontaneously break down into its active form to form the C three B and C three A. Now, the thing is, under normal conditions, when we don't have any pathogenic agents, for example, bacterial cells in our body, when we only have these normal cells around these molecules, what happens is the C three B quickly attaches onto a special inhibitory protein found on the membrane of nearby healthy cell.