chapter 43 ap bio
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Chapter 43By Ben Karlsberg
Compliment system Consists of roughly 30 proteins in blood
plasma that function together to fight infections
Activated by substances on the surfaces of microbes
Inflammatory response Swelling from a wound Histamine (chemical signal) released from
mast cells (connective tissue cells that store chemicals in granules for secretion)
Capillaries widen and phagocytes are released
Phagocytes engulf bacteria, dead cells, and cellular debris as tissue heals
Natural Killer Cell Kills cells that don’t express class I MHC
protein because infected cells often lose this protein
Lymphocytes T-cells are lymphocytes that migrate from
bone marrow to the thymus to mature B-cells mature in bone marrow Cytokines are released by phagocytic cells
to activate and recruit lymphocytes
Immunoglobulin (antibody) Recognize epitopes (antigenic determinant)
of antigens and bind to them Very specific B-cells recognize epitopes in intact
antigens T-cells recognize epitopes in small antigen
fragments
5 classes of antibodies
Major histocompatibility (MHC) molecules
Class I MHC display peptide antigens to cytotoxic T-cells
Class II MHC display antigens to helper T-cells
Short and long term responses Effector cells- attack antigen instantly –
short living Memory cells- bear receptors specific for an
antigen- long living
Helper T-cells Make CD4 (surface protein that enhances
binding to class II MHC molecules) Activated helper t-cells secrete different
cytokines that stimulate other lymphocytes
Cytotoxic T-cells Make CD8, enhances binding to Class I
MHC Activated- secrete proteins that initiate
destruction of target cells
B-cells Clonal selection of B-cells generates
antibody-secreting plasma cells Binding of antibodies to antigens leads to
elimination by phagocytosis and compliment-mediated lysis
Autoimmune disease HIV- destroys helper t-cells AIDS – Acquired Immunodificiency
syndrome interferes with cell communicated defenses