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CHAPTER 24

CHAPTER 24. 24.1. Nonspecific Defenses: Innate Immunity. Components : skin, sweat, saliva, tears, mucous membranes lining organ systems that open to the external environment—digestive/respiratory/ genitourinary, stomach acid, nose hair, cilia. Innate defensive cells:

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CHAPTER 24

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  1. CHAPTER 24

  2. 24.1 Nonspecific Defenses:Innate Immunity Components: skin, sweat, saliva, tears, mucous membranes lining organ systems that open to the external environment—digestive/respiratory/ genitourinary, stomach acid, nose hair, cilia

  3. Innate defensive cells: • Phagocytes: white blood cells that eat bacteria & foreign materials that enter the body • Neutrophils: engulf microbes in infected tissue • Macrophages: develop from monocytes & phagocytize bacteria & virus-infected cells,…they wander actively in interstitial fluid

  4. Natural Killer Cells: attack cancer cells & virus infected cells by releasing chemicals that promote apoptosis (AKA-programmed cell death) NOTE: All types of these white blood cells leave the blood & scavenge invading cells in the interstitial fluid & body tissues [Not phagocytic]

  5. Innate defense by proteins: either attack microbes directly or impede their production Interferons: proteins produced by virus-infected cells that help other cells resist viruses (Fig. 24.1B p. 486) Complement system: about 30 proteins that circulate in the blood plasma and work with other defense mechanisms

  6. 24.2 • Inflammatory Response: • Any damage to tissue (microorganisms or physical injury) triggers this response,… injured cells release histamine – this causes the blood vessels in vicinity to dilate & become leakier

  7. WBC’s that rushed to the area engulf microorganisms & clean up debris pus = dead WBCs that accumulate in area, along w/fluids Response to an infection may be localized or systemic systemic – infection is widespread so more WBCs will circulate,…fever (good and/or bad) may result

  8. THE LYMPHATIC SYSTEM Components: Lymphatic system consists of branching network of vessels, lymph nodes, thymus, tonsils, appendix, spleen, bone marrow 24.3

  9. Lymphatic vessels carry a fluid called lymph. Lymphatic system has 2 main functions: 1return tissue fluid to circulatory system 2fight infections

  10. Circulation of Lymph: • Lymph enters system through open lymphatic capillaries • Largest lymph ducts (R lymphatic duct & thoracic duct) empty into circulatory system’s veins in shoulders • As lymph circulates, microbes from infected sites & cancer cells can be phagocytized by macrophages

  11. The Immune Response The Immune System: • When the nonspecific defense mechanisms fail, the immune system provides another line of defense - usually more effective than nonspecific - can amplify certain nonspecific responses

  12. The immune system recognizes foreign materials in the body: - foreign invaders are called antigens - can include certain molecules on the surfaces of viruses, bacteria, mold spores, cancer cells, pollen

  13. Bacillus anthracis : anthrax Bordetella petussis : whooping cough Clostridium botulinum : botulism Clostridium tetani : tetanus Escherichia coli : acute pyelonephritis Lactobacillus acidophilus : cavities Neisseria gonorrhoeae : gonorrhoea Salmonella typhimurium : food poisoning Streptococcus mutans : cavities Streptococcus pneumoniae : pneumonia Treponema pallidum : syphilis Vibrio cholerae : cholera Bacteria Bad Boys

  14. Antibody - a protein found in blood plasma that attaches to one particular kind of antigen & helps counter its effects • - antibodies do not recognize the whole antigen, only the localized region on the surface known as the antigenic determinant

  15. binding sites on the antibody & • antigenic deter- • minant have • complementary • shapes • (lock & key)

  16. Immunity means resistance to specific invaders: - acquired by natural infection, or - acquired by vaccination (weakened or inactive form of the pathogen)

  17. 2 TYPES 1. Active immunity - achieved either naturally or artificially when foreign materials enter the body

  18. 2. Passive immunity - achieved when antibodies pass from mom to fetus or to a nursing newborn or when travelling (GG shots)

  19. The Immune Response Cells of the Immune System: Lymphocytes - WBCs that produce the immune response,…they come from stem cells in bone marrow.

  20. -some lymphocytes continue to develop in bone marrow & become specialized B cells -others are carried by blood to thymus & become specialized as T cells -humans can have 100 million to 100 billion different B cells & T cells

  21. B cells provide humoral immunity -B cells secrete antibodies that are carried by blood & lymph to the site of infection -this system defends against bacteria & viruses present in body fluids -can be transferred passively by plasma donation

  22. T cells provide cell-mediated immunity -defends against bacteria, viruses, fungi, protozoans, & cancer cells inside body cells -circulate in blood & mount a cellular attack on repeated foreign invaders

  23. Both T & B cells must mature before they are able to function in defense of the body • - must be able to recognize & respond to a specific antigen

  24. must have specialized regions on their • surface known as antigen receptors

  25. Both T & B cells will make memory cells in response to an antigen • - they are activated by a second exposure to an antigen • - seem to confer life immunity (measles, chicken pox)

  26. The Immune Response • Humoral Immunity: • response is mediated by the production of antibodies made by B cells • each antibody is made of 4 polypeptide chains: 2 heavy & 2 light chains (this gives it a Y shape)

  27. Each of the 4 chains of the antibody has a constant (C) region: • - constant role in destroying invading cells is to mark them for destruction (opsonization) • - phagocytes will then destroy the antigen

  28. Variable region (V) is at the tip of each arm of the Y • forms an antigen-binding site

  29. Cell-mediated Immunity: • this defense mechanism is produced by T cells & battles pathogens that have already entered body cells • T cells do not make antibodies - they make proteins known as T cell Receptors

  30. When a T cell recognizes foreign antigens, they differentiate into effector cells • - cytotoxic T cells kill target cells directly

  31. * receptors on the T cells recognize antigenic determinants on the target * target cell will then be lysed * T cells may also attack cancer cells & prevent them from spreading

  32. Helper T cells: (many roles) • - help activate cytotoxic T cells & macrophages • - help stimulate B • cells to make antibodies • - interact w/other WBCs that function as antigen-presenting cells (APCs) - these cells present a foreign antigen to the helper T cell

  33. Self from Nonself(Blood Types) • For each blood type there is an antigen present on the surface of the RBC - Type O has no antigens - Type A has antigen A - Type B has antigen B - Type AB has antigens A & B

  34. Blood types w/antigens on the surface do not have antibodies against that antigen • another blood group • antigen is the Rh factor

  35. - antibodies produced by mom can react w/blood of fetus - problems when Rh(-) mom produces antibodies against Rh(+) fetus

  36. Platelets are joined w/fibrinogen • Fibrin forms • 3. Clots form (Our bodies respond to antigens)

  37. Major Histocompatibility Complex • Ability to distinguish self from nonself (MHC) • acts as your biochemical finger-print: it is 2 sets of self proteins on surfaces of our cells • this complex must be considered before any kind of transplant is done

  38. Immunological Malfunction • Autoimmune disease - when the immune system turns against its own body - lupus, rheumatoid arthritis, scleroderma Lupus,…people develop immune reactions against their own nucleic acids; deposits of antibody-nucleic acid complexes accumulate causing inflamed joints & kidney

  39. Immunodeficiency diseases cause part or all of the immune system to be lacking -Hodgkin’s Disease is a lymphocyte cancer -Severe Combined Immunodeficiency (SCID) is when both B & T cells are lacking or inactive (sensitivity to minor infections)

  40. Allergies are overreactions to certain environmental antigens • - these antigens are called allergens (dust, pollen, insect toxins, cat saliva) • - allergic reactions are usually rapid & occur in nasal passages, skin, bronchi

  41. -antibodies trigger allergic reactions by binding to,… mast cells: noncirculating cells located in connective tissue -the antibody & mast cell combo binds to an antigen

  42. Mast cells Basophils T lymphocytes Neutrophils Eosinophils Histamine Tryptase Prostoglandins Leukotrienes Cytokines Chemokines

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