How many types of immunoglobulin are in a human's Immune System?

First of let's star by defining Immonuglobulins, these are any of a class of proteins present in the serum and cells of the immune system, that function as antibodies. There are 5 types of immunoglobulins and these are: 

               • Immunoglobulin M (IgM) is the third most common antibody class and the predominant  

                 antibody produced first during a primary humoral immune response.

              •  Immunoglobulin G (IgG) is the predominant antibody class found in the bloodstream and  

                 the primary defender against invading bacteria.

              •  Immunoglobulin A (IgA) is the antibody class most commonly associated with various 

                 body secretions, including tears and milk. IgA pairs with a secretory component to form 

                 secretory IgA.

              •  Immunoglobulin E (IgE) is the signal antibody molecule that triggers the release of cell-

                 damaging molecules onto parasites, particularly parasitic worms.

              •  Immunoglobulin D (IgD) is a membrane-bound antibody molecule found in some animals as 

                 a B cell receptor.

The immunoglobulins that is activated depends on the type of pathogen that enters the body.