The Immune System
Terms
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- 2 types of lymphocytes involved in immune response
- T-lymphocytes and B-lymphocytes
- responsible for cell-mediated response
- T-cells
- responsibel for humnoral antibody response
- B-cells
- cytotoxic T-cells
- recognize and destroy cells with foreign surface antigens
- plasma cells
- secrete immunoglobulins thant bind to specific antigens and facilitate their removal
- immunoglobulin
- glycoproteins; 4 chains: 2 heavy & 2 light
- Fab
- fragment, antigen-binding; arms; selectively bind to antigen
- Fc
- fragment, crystallizable; binds to surface of cells (macrophages)
- IgM
- first; during primary immune response
- short-lived antibody
- IgM
- IgG
- later; during secondary immune response
- long-lasting antibody
- IgG
- IgA
- found in bodily secretions
- antibody responsible for mucosal immunity
- IgA
- IgE
- found on surfaces of mast cells and basophils
- antibody responsible for allergic reactions
- IgE
- IgD
- found on surfaces of B-cells
- antibody that is little present in serum
- IgD
- B-cell
- produces 1 kind of antibody specific for a given antigen
- usually expresses IgM or IgD
- B-cells
- How are some plasma cells formed?
- proliferation and differentiation of a B-cell
- How are B memory cells formed?
- when B-cells do not become plasma cells and acquire more surface antibody
- What enables an organism to mount a humoral response quicly if exposed to a secondary response?
- B memory cells
- lack of b memory cells causes?
- primary response to be slow
- TH2 cells (T helper cells)
- help activate B cells
- How can T cells respond to antigens?
- only if on surface of antigen-presenting cell APC
- E.g. of APC
- macrophages, dendritic cells, B-cells, and epithelial-reticular cells
- MHC
- major histocompatibility complex- cluster of genes on chromosome 6
- MHC Class 1
- all multnucleated cells of body and platelets
- MHC Class 2
- only on APCs
- CD4 surface marker
- T helper cells
- t-helper cells
- MHC 2 restricted
- TH1 cells
- promote cell-mediated immunity
- TH2
- promote humoral immunity
- t cells that promote destruction of cancerous or virally-infected host cells and invading microorganisms
- TH1
- t cells that promote production of antibody against foreign antigens
- TH2
- CD8 surface marker
- cytotoxic T cells
- secrete perforins and fragmentins that cause target cell to lyse or undergo apoptosis
- cytotoxic t cells
- cytotoxic t cells
- MHC 1 restricted
- T suppressor cells
- CD8 marker; suppress humoral and cell-mediated response
- null cells
- natural killer; spontaneous cytotoxic activity; do not require prior activation; non-specific; no MHC restriction
- antibody-dependent cell-mediated cytotoxicity
- NK cells
- cytokines
- exert inhibitory and facilitory effects on lymphocytes and APCs
- e.g. of cytokines
- interleukins, interferons, tumor-necrosis factor
- lymph nodes
- where lymph filters and returns to the blood stream
- remain in lymph tissue
- B-cells
- recirculate b/w bloodstream and lymph
- T-cells
- Lymphocyte recirculation
- lymphocytes cross postcapillary venules, leave lymph nodes thru efferent lymphatic vessels, and pass into channel (thoracic duct)
- 3 functions of spleen
- 1. produces humoral antibody to blood-borne antigen 2. disposes of defective blood cells and other particulate matter in the blood 3. stores blood cells and platelets
- splenic pulp
- parenchyma; supported on stroma; div. into red and white
- 2 components of red pulp
- 1. sinusoids-thin-walled venous cannels 2. reticular fiber networkprod. by ret. fibers w/ blood cells
- pulp arteries
- where arterial blood enters the red pulp
- penillar arteries
- smaller branches of pulp arteries; b/w sinusoids
- what filters blood?
- spleen
- follicular arteries
- branches of sheathed arteries
- lymphatic sheath
- composed of T-lymphocytes
- lymphatic nodules
- composed of B-lymphocytes
- marginal zone
- interface b/w white and red
- complement fixation
- plasma proteins combine with antigen-antibody complexes
- Results of complement fixation
- 1. cell lysis-invading bacteia 2. chemotactic factors-attract phagoctic cells 3. phagocytosis (opsonization)
- central lymphoid tissue
- where new lymphocytes are produced
- bone marrow
- b-lymphocyte differentiation
- thymus
- t-lymphocyte differentiation
- peripheral lymphoid tissue
- aggregation of lymphocytes; sites where lymphocytes respond to antigen;
- components of cental lymphois tissue
- bone marrow and thymus
- components of peripheral lymphoid tissue
- lymphatic nodules, lymph nodes, and spleen
- phagocytotic cells that possess Fc and C3 receptors
- neutrophils, eosinophils, and monocytes