Immune System Flashcards
B-Lymphocytes (B-cells)
Made and mature in bone marrow. Activated in spleen or lymph nodes. Express antibodies on its cell surface.
Antibodies (lg)
Produced by plasma cells, which are activated B-Cells. Target an antigen. Contain 2 heavy chains and 2 light chains. Constant region & variable region. Tip of variable region is the antigen-binding region.
Memory B-Cells
Lie in wait for a second exposure to pathogen. Secondary response is more rapid and vigorous.
Humoral Immunity
Centers on antibody production by B-Cells. Kills antigens while they are floating around in the fluid (humor).
Cell-Mediated (Cytotoxic) Immunity
Centers on T-Cells. Responds to cells once they have been infected by the antigen.
T-Lymphocytes (T-cells)
Made in bone marrow, mature in Thymus. Coordinate immune system and directly kill infected cells. Cell- mediated immunity.
Positive/Negative Selection
Maturation of T-Cells. Facilitated by thymosin. Occurs in Thymus.
Positive Selection
Mature only T-cells that can respond to the presentation of antigen on MHC.
Negative Selection
Causes apoptosis in T-cells that are self-reactive.
Helper T-Cells
Th or CD4+. Respond to antigen on MHC-II. Coordinate rest of the immune system, secreting lymphokines to activate immune defense.
Th1 – secrete interferon gamma
Th2 – activate B-Cells, in parasitic infections
Cytotoxic T-cells
Tc, CTL, or CD8+. “Killer cells”. Respond to antigen on MCH-I and kill virally infected cells
Adaptive Immunity
Composed of Humoral (B-Cells) and Cytotoxic (T-Cells) immunity.
Defenses that take time to activate and are SPECIFIC to the invader.
Innate Immunity
Defenses that are always active but NON- SPECIFIC. Skin, mucus, stomach acid, tears etc.
Defensins
Antimicrobial enzymes secreted by skin.
Lysozymes
Antimicrobial compound in tears and saliva.
