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.
Complement System
Can punch holes in the cell walls of bacteria making them osmotically unstable, leading to lysis. Also triggers opsonization.
Dendritic Cells
Antigen-presenting cells in the skin
Neutrophils
Activated by bacteria, conduct phagocytosis. Quickly migrate to sites of infection and activate the immune response.
Eosinophil
Activated by parasites & allergens ↑histamines
