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Transcript
THE BODY’S DEFENSE CHAPTER 43 Figure 43.4 The human lymphatic system Figure 43.0 Specialized lymphocytes attacking a cancer cell Figure 43.2 First-line respiratory defenses. Inside the lining of the trachea. Yellow cells are ciliated. Orange cells secrete mucus. Figure 43.1 An overview of the body's defenses NONSPECIFIC DEFENSE • Skin • Mucus • Secretions CELLS: Nonspecific • Neutrophils - engulf microbes (phagocytosis); self-destruct after destroy microbes • Monocytes - develop into macrophages which can migrate into tissues and engulf microbes Figure 43.x1 Anabaena (a blue-green algae that makes a toxin, which causes cell death) phagocytosed by a human neutrophil Anabaena Figure 43.3x Macrophage Figure 43.3 Phagocytosis by a macrophage Bacilli Pseudopodia of macrophage • Esinophils - destroy parasitic worms • Natural killer cells - destroy viral-infected cells INFLAMMATORY RESPONSE • Arterioles dilate to increase blood flow to damaged area • Increased WBC in damaged area • Histamine and prostaglandins released to dilate arterioles • Chemokines - chemical signals for cells to follow Figure 43.5 A simplified view of the inflammatory response SPECIFIC DEFENSE • Response is to a specific microbe • Antigen - foreign molecule • Antibody - proteins made to attach to specific antigens CELLS:Specific • B lymphocytes - develop in bone marrow; differentiate into plasma cells which secrete antibodies; also make memory cells • T lymphocytes - develop in thymus; activate B cells and other WBC; also make memory cells Figure 43.8 The development of lymphocytes Figure 43.8x B lymphocyte Figure 43.6 Clonal selection • Primary immune response first exposure; 10 - 17 days; make antibodies • Secondary immune response already been exposed; 2 - 7 days; memory cells make antibodies quickly Figure 43.7 Immunological memory TOLERANCE FOR SELF • Major histocompatibility complex (MHC) on cells – Class I MHC on all nucleated cells – Class II MHC on macrophages, B cells and activated T cells – Biochemical fingerprint – As your cells develop, if fingerprint is wrong then cell death occurs – MHC molecules cradle foreign antigens. They present the antigen to other cells. •MHC I presents antigens to Cytotoxic T cells which kill bad cells •MHC II presents antigens to Helper T cells – Cells that present antigens are called antigen presenting cells. These include macrophages and B Figure 43.9 The interaction of T cells with MHC molecules HUMORAL VS. CELL MEDIATED IMMUNITY • Humoral - B cells activated by free antigens (free bacteria, toxins, viruses) • Cell mediated - depends on T cells; active against cells infected with viruses and bacteria; as well as free fungi, protozoa, and worms Figure 43.9 The interaction of T cells with MHC molecules Figure 43.10 An overview of the immune responses (Layer 4) T Helper Cells • Antigen presenting cells (APC) include B cells and macrophages • Present antigen on class II MHC • T helper cell binds to MHC II with antigen • CD4 on Th cell holds APC cell and Th cell together • Th then activates T cytotoxic cells • T cytotoxic cells can then lyse infected cells Figure 43.11 The central role of helper T cells: a closer look Figure 43.12a The functioning of cytotoxic T cells Figure 43.12b A cytotoxic T cell has lysed a cancer cell ANTIBODY PRODUCTION • T-dependent antigens - B cell must be activated by Th cell; most protein antigens • T-independent antigens directly stimulate B cells to make antibodies; mostly polysaccharide antigens Figure 43.13 Humoral response to a T-dependent antigen (Layer 3) ANITBODY MEDIATED DISPOSAL OF ANITGEN • Opsonization - many antibodies bound to antigen enhance macrophage phagocytosis • Agglutination - antibodies attach to many antigens; clumping them together to enhance phagocytosis Figure 43.16 Effector mechanisms of humoral immunity ACTIVE IMMUNITY • Depends on response of infected person’s immune system • May be artificially induced by vaccinations Figure 43.x2 Vaccination PASSIVE IMMUNITY • Antibodies transferred from one individual to another • Some antibodies can move across placenta to baby in pregnant women • Nursing HEALTH AND DISEASE • Review ABO blood types and Rh • MHC causes tissue and organ rejections • In bone marrow transplants, donated marrow (with WBC) will react against recipient • Allergies - overproduction of certain antibodies causes histamine to be released – Runny nose – Teary eyes – Smooth muscle contractions = hard breathing Figure 43.x4 Alternaria spores, a cause of allergies in humans • Anaphylactic shock - lifethreatening reaction; abrupt dilation of arteries causes serious drop in blood pressure • Autoimmune diseases - attack own body – Lupus, rheumatoid arthritis, MS • Immunodeficiency Diseases – Severe combined immunodeficiency (SCID), Hodgkin’s Figure 43.x3 X-ray of hands with arthritis • AIDS - acquired immunodeficiency syndrome – Two major strain: HIV I and HIV II – Bind to CD4 and therefore Th cells – Insert its RNA and reverse transcriptase makes viral DNA that is inserted into host’s DNA – Exists as provirus so antibodies can’t get rid of it easily – Mutates often – May cause Th cell death – HIV positive = presence of HIV antibodies Figure 43.19 A T cell infected with HIV Figure 43.19x1 HIV on a lymphocyte, detail Figure 43.20 The stages of HIV infection Figure 43.x5 AIDS posters