So let's suppose we have the antigens floating around in our blood or in our lymph or in our tissue. Now, when this specific antibody that was built by the plasma cell approaches these specific antigens for which it was built for in the first place, we have a binding process taking place and the epitome basically binds onto the antigen binding side of this antibody as shown in the following diagram. And then we form our antibody antigen complex which then elicits some type of defense or response as we'll discuss in just a moment. Now, what about the constant regions? So basically earlier we said that we have five different types of five different classes or five different types of antibodies. Now, each class of antibody has the same exact constant region.