IMMUNOLOGY

Detailed explanation-1: -1) Antibodies are secreted into the blood and mucosa, where they bind to and inactivate foreign substances such as pathogens and toxins (neutralization). 2) Antibodies activate the complement system to destroy bacterial cells by lysis (punching holes in the cell wall).

Detailed explanation-2: -complement fixation. noun. : the process of binding serum complement to the product formed by the union of an antibody and the antigen for which it is specific that occurs when complement is added to a mixture (in proper proportion) of such an antibody and antigen.

Detailed explanation-3: -After an antigenic challenge, antibodies are secreted by differentiated B cells called plasma cells. Antibodies have two predominant roles that involve specific binding to antigens to launch an immune response, along with activation of other components of the immune system to fight pathogens.

Detailed explanation-4: -Three types of antibody interactions with phagocytic cells are seen: direct binding of antibody to the surface of the phagocytic cells (cytophilic antibody), uptake of antigen antibody complexes through the Fc receptor, and uptake of antigen-antibody-complement complexes through the C3b receptor (see Ch.

Detailed explanation-5: -Antibodies recognize foreign invading microorganisms by specifically binding to a pathogen’s proteins or antigens, facilitating their neutralization and destruction. Antigens are classically defined as any foreign substance that elicits an immune response.