Question

How many different pathways can be involved in the activation of complement?

1) 4
2) 2
3) 3
4) only 1

Answer 1

Three different pathways—classical, alternative, and lectin—are involved in the activation of the complement system, leading to the destruction of pathogens.

Step-by-step explanation:

There are three different pathways involved in the activation of complement: the classical pathway, the alternative pathway, and the lectin pathway. The classical pathway is activated by antibodies attached to the surface of a pathogen. The alternative pathway is triggered spontaneously when C3 convertase breaks down C3 in the absence of antibodies. The lectin pathway becomes active when an acute-phase protein binds to a pathogen. These pathways ultimately lead to the formation of the membrane-attack complex (MAC), contributing to an inflammatory response and elimination of the pathogen.