Potential Essay Question

1. Describe innate and adaptive immune systems, how they work and how they interact. Adaptive immunity – is the ability of the body to defend itself against specific invading agents  Antigens are substances recognized as foreign that provoke immune responses Adaptive immunity has both specificity and memory and is divided into 2 types  Cell – mediated Immunity  Antibody – mediated Immunity In cell-mediated immunity:  An antigen is recognized and bound  A small number of T cells proliferate and differentiate into a clone of effector cells  The antigen is eliminated In antibody-mediated immunity:  An antigen is recognized and bond  Helper T cells costimulate the B cell so the B cell can proliferate and differentiate into a clone of effector cells that produce antibodies  The antigen is eliminated Innate immunity – refers to a wide variety of body responses that serve to protect us against invasion of a wide variety of pathogens and their toxins  We were born with this kind of immunity  Two line of defense: Nonspecific disease resistance fight a wide variety of invaders. o 1st : Skin and mucus membranes: barriers, antimicrobial substances o 2nd : Internal defenses (cellular defenses), inflammation, and fever 2. Explain the various subclasses of antibodies – how they are similar, how they differ. Immunoglobulins (Ig) – most antibodies contain 4 polypeptide chains with 2 identical heavy chains and 2 light chains, a hinge region, stem region, variable regions, antigen- binding site, and a constant region. Antibodies neutralize antigens, immobilize bacteria, agglutinate and precipitate antigens, activate complement, and enhance phagocytosis. IgG – Most abundant ( 80% of antibodies in blood). Found in the blood, lymph and intestines. Protects against bacteria and viruses by enhancing phagocytosis, neutralizes toxins, and triggering complement system. The only antibody that will cross placenta. IgM – Found in blood and lymph (10 – 15% of antibodies in blood). First to be secreted by plasma cells after initial exposure to any antigen. Activates complement and causes agglutination and lysis. In blood plasma, anti-A and anti-B antibodies of ABO blood group, which bind to A and B antigens during incomplete blood transfusions. IgD – Found on surfaces of B cells as antigen receptors. Activates B cells. 0.2% of antibodies in bloods.