Only $2.99/month

Terms in this set (30)

white blood cells that recognize specific invaders
originate in bone marrow from stem cells
B Cells: continue development in bone marrow
humoral immunity
has antibody proteins embedded in its surface as specific receptors for antigens
B cells containing the matching antigen receptor binds to the antigens of the pathogen. this activates the B cell. Activation: B cell grows and clones itself. Each of these cells can develop into a PLASMA CELL which produces and secrets antibodies specific to the antigen that activated the B cell. this is CLONAL SELECTION
some of the daughter cells become MEMORY CELLS.
they are then carried via the lymph and blood to site of infection
receptors are Y-shaped and consist of 4 polypeptide chains

T Cells: transported to the thymus gland where they mature
cell-mediated immunity
directly attack host cells that contain multiplying bacteria or viruses. each t cell has receptors for a specific antigen. when a pathogen infects a body cell..the pathogen's antigens are displayed on the surface of the body cell. antigens bind to the receptors of the "matching" T cell and activate the T cell. activated T cells will then divide and produce clones. these clones develop into CYTOTOXIC T CELLS, which attack cells infected with the pathogen that triggered the response. they bind to an infected cell's membrane and poke holes in it by secreting perforin. the infected cell dies.
receptors consist of two polypeptide chains


Both B and T cells travel in the blood to the lymph nodes and other parts of the lymphatic system
there are a laarge variety of antigen receptors