1 / 35

Chapter 43.

phagocytic leukocyte. Chapter 43. Immune System. lymphocytes attacking cancer cell. lymph system. Why an immune system?. Attack from outside animals must defend themselves against unwelcome invaders viruses  protists bacteria  fungi we are a tasty vitamin-packed meal

ailis
Download Presentation

Chapter 43.

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. phagocytic leukocyte Chapter 43. Immune System lymphocytes attacking cancer cell lymph system

  2. Why an immune system? • Attack from outside • animals must defend themselves against unwelcome invaders • viruses protists • bacteria  fungi • we are a tasty vitamin-packed meal • cells are packages of macromolecules • no cell wall • traded mobility for susceptibility • Attack from inside • defend against abnormal body cells = cancers

  3. Lines of defense • 1st line: Barriers • broad, innate, external defense • “barbed wire” • skin & mucus membranes • 2nd line: Non-specific patrol • broad, innate, internal defense • “untrained soldiers” • leukocytes (WBCs) • 3rd line: Immune system • specific, acquired immunity • “elite trained units” • lymphocytes & antibodies

  4. 1st: External defense • non-specific defense • external barrier • epithelial cells & mucus membranes • skin • respiratory system • digestive system • genito-urinary tract Lining of trachea: ciliated cells & mucus secreting cells

  5. 1st: Chemical barriers on epithelium • Skin & mucous membrane secretions • sweat • pH 3-5 • tears • washing action • mucus • traps microbes • saliva • anti-baterial = “lick your wounds” • stomach acid • pH 2-3 • anti-microbial proteins • lysozyme • digests bacterial cell walls

  6. 2nd: Internal, broad range patrol leukocytes • innate defense • rapid response • cells & proteins • attack invaders that penetrate body’s outer barriers • leukocytes • phagocytic white blood cells • anti-microbial proteins • inflammatory response • natural killer cells

  7. Leukocytes: Phagocytic WBCs • Neutrophils • attracted by chemical signals released by damaged cells (interferon) • enter infected tissue, engulf & ingest microbes • amoeba-like • lysosomes • ~3 day life span • Macrophages • “big eater” • bigger, long-lived phagocytes

  8. Phagocytes macrophage yeast

  9. Production & transport of leukocytes Traps foreign invaders Lymph system lymph vessels (intertwined amongst blood vessels) lymph node

  10. Development of Red & White blood cells inflammatory response Red blood cells fightparasites short-lived phagocytes 60-70% WBC develop into macrophages

  11. Inflammatory response • Reaction to tissue damage Pin or splinter Blood clot swelling Bacteria Chemical alarm signals Phagocytes Blood vessel

  12. Inflammatory response • Damage to tissue triggers local inflammatory response • histamines & prostaglandins released • capillaries dilate, more permeable • lead to clot formation • increased blood supply • swelling, redness & heat of inflammation & infection • delivers WBC, RBC, platelets, clotting factors

  13. Fever • When a local response is not enough • systemic response to infection • activated macrophages release interleukin-1 • triggers hypothalamus in brain to readjust body thermostat to raise body temperature • higher temperature helps defense • inhibits bacterial growth • stimulates phagocytosis • speeds up repair of tissues • causes liver & spleen to store iron reducing blood iron levels • bacteria need large amounts of iron to grow

  14. 3rd: Acquired Immunity • Specific defense • lymphocytes • B lymphocytes (B cells) • T lymphocytes (T cells) • antibodies • immunoglobulins • Responds to… • specific microorganisms • specific toxins • abnormal body cells • antigens

  15. Antigens • Proteins that serve as cellular name tags • foreign antigens cause response from WBCs • proteins belonging: • viruses, bacteria, protozoa, parasitic worms, fungi, toxins • non-pathogens: pollen & transplanted tissue • B cells & T cells respond to different antigens • B cells recognize intact antigens • invaders in blood & lymph • T cells recognize antigen fragments • invaders which have infected cells “self” “foreign”

  16. Lymphocytes • B cells • mature in bone marrow • humoral response system • “humors” = body fluids • produce antibodies • T cells • mature in thymus • cellular response system • Learn to distinguish “self” from “non-self” antigens during maturation

  17. B cells • Humoral response = “in fluid” • defense against attackers circulating freely in blood & lymph • Specific response • recognizes specific antigen • produces antibodies against it • tagging protein = immunogloblin • millions of different B cells, each produces different antibodies,each recognizes a different antigen • types of B cells • plasma cells • immediate production of antibodies • short term release • memory cells • long term immunity

  18. Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Antibodies Y Y • Proteins that bind to a specific antigen • multi-chain proteins produced by B cells • antibodies match molecular shape of antigens • immune system has antibodies to respond to millions of antigens (invaders) • tagging system • “this is foreign!” Y Y Y Y Y variable binding region Y Y Y Y each B cell has ~100,000 antigen receptors

  19. How antibodies work

  20. Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y invader(foreign antigen) B cells + antibodies memory cells “reserves” recognition Y capturedinvaders Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y clone 1000s of clone cells plasma cells release antibodies 10 to 17 days for full response B cell immune response tested by B cells

  21. 1° vs 2° response to disease • Memory B cells allow a rapid, amplified response with future exposure to pathogen

  22. How can we have so many antibody proteins & so few genes? Variable region Antibody Constant region Light chain B cell Heavy chain Variable DNA combinations: • 1M different B cells • 10M different T cells Rearrangement of DNA Translation of mRNA Transcription of gene V mRNA 40 genes for Variable region DNA of differentiated B cell D J C C Chromosome of undifferentiated B cell

  23. Vaccinations • Active immunity • immune system exposed to harmless version of pathogen • Stimulates immune system to produce antibodies to invader • rapid response if future exposure • Most successful against viral diseases

  24. 1914 – 1995 Jonas Salk • Developed first vaccine • against polio April 12, 1955

  25. Polio epidemics

  26. Passive immunity • Maternal immunity • antibodies pass from mother to baby across placenta or in breast milk • critical role of breastfeeding in infant health • mother is creating antibodies against pathogens baby is being exposed to • Injection • injection of antibodies • short-term immunity

  27. T cells • Immune response to infected cells • defense against invaders inside infected cells • viruses & bacteria within infected cells, fungi, protozoa & parasitic worms • defense against “non-self” cells • cancer & transplant cells • Kinds of T cells • helper T cells • stimulate immune system • killer T cells • attack infected body cells

  28. T cell How are cells tagged with antigens • Glycoproteins on surface of cells have unique “fingerprint” • major histocompatibility proteins (MHC) • human leukocyte antigens (HLA) • MHC proteins constantly export bits of cellular protein to cell surface • “snapshot” of what is going on inside cell MHC proteins displaying self-antigens

  29. T cell How do T cells know a cell is infected • Infected cells digest some pathogens & export pieces to MHC proteins on cell surface • antigen presenting cells (APC) invading pathogen MHC proteins displaying foreign antigens T cell antigen receptors

  30. Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y killerT cell activatekiller T cells stimulateB cells &antibodies helperT cell helperT cell helperT cell helperT cell helperT cell Y Y Y Y Y Y Y Y T cell response infected cell interleukin 2 interleukin 1 or activated macrophage interleukin 2

  31. Attack of the Killer T cells • Destroys infected body cells • binds to target cell • secretes perforin protein • punctures cell membrane of infected cell Vesicle Killer T cell Killer T cellbinds toinfected cell Perforin puncturescell membrane Cell membrane Cell membrane Infected cell destroyed Target cell

  32. Y Y Y Y Y Y Y antibodies Y Y Y Y Immune response pathogen invasionantigenexposure free antigens in blood antigens on infected cells macrophages humoral response cellular response helperT cells B cells T cells plasmaB cells memoryB cells memoryT cells cytotoxicT cells

  33. HIV & AIDS • Human Immunodeficiency Virus • virus infects helper T cells • helper T cells don’t activate rest of immune system: T cells & B cells • also destroy T cells • Acquired ImmunoDeficiency Syndrome • infections by opportunistic diseases • death usually from other infections • pneumonia or cancer

  34. Immune system malfunctions • Auto-immune diseases • immune system attacks own molecules & cells • lupus • antibodies against many molecules released by normal breakdown of cells • rheumatoid arthritis • antibodies causing damage to cartilage & bone • diabetes • beta-islet cells of pancreas attacked & destroyed • multiple sclerosis • T cells attack myelin sheath of brain & spinal cord nerves • Allergies • over-reaction to environmental antigens • allergens = proteins on pollen, from dust mites, in animal saliva

  35. Key attributes of immune system • 4 attributes that characterize the immune system as a whole • specificity • antigen-antibody specificity • diversity • react to millions of antigens • memory • rapid 2° response • ability to distinguish self vs. non-self • maturation & training process to reduce auto-immune disease

More Related