Immune / Lymphatic System (Ch. 43)

1. Immune / Lymphatic System (Ch. 43)

2. Why an immune system? • Attack from outside • animals are a tasty nutrient- & vitamin-packed meal • cells are packages of macromolecules • animals must defend themselves against invaders (pathogens) • Viruses: HIV, flu, cold, measles, chicken pox • Bacteria: pneumonia, meningitis, tuberculosisLyme disease • Fungi: yeast (“Athlete’s foot”…) • Protist: amoeba, malaria • Attack from inside • cancers = abnormal body cells

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

4. 1st line: Non-specific External defense Lining of trachea: ciliated cells & mucus secreting cells • Barrier • Skin – sweat (acidic) • Traps • mucous membranes, cilia,hair, earwax • Elimination • coughing, sneezing, urination, diarrhea • Lysozyme – enzyme that breaks cell wall of bacteria in mucus, saliva, sweat, tears.

5. 2nd line:Non-specific patrolling cells bacteria • Patrolling cells & proteins • attack pathogens, but don’t “remember” for next time • Leukocytes • phagocytic white blood cells • macrophages, neutrophils, natural killer cells • inflammatory response (next slide) • increase in body temp. • increase capillary permeability • attract macrophages macrophage yeast

6. Inflammatory response • Damage to tissue triggers local non-specific inflammatory response • release chemical signals • histamines & prostaglandins • capillaries dilate, becomemore permeable (leaky) • delivers macrophages, RBCs, platelets, clotting factors • fight pathogens • clot formation • FEVER - When a local response is not enough • system-wide 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 • causes liver & spleen to store iron, reducing blood iron levels • bacteria need large amounts of iron to grow

7. Interferon – (“interferes” with virus) • Virus infected cells produce a group of proteins that help other cells resist viral infections. • Interferons inhibit the synthesis of viral proteins in infected cells and block viral replication!

8. 3rd line: Acquired (active) Immunity B cell • Specific defense with memory • lymphocytes • B cellsand T cells • antibodies(B cells) • immunoglobulins • Responds to… • antigens(substance that triggers a response) • specific pathogens • specific toxins • abnormal body cells (cancer)

9. How are invaders recognized? • Antigens –carbs, proteins, lipids on cell surface • “self” antigens • no response from WBCs • “foreign” antigens • response from WBCs • pathogens: viruses, bacteria, protozoa, parasitic worms, fungi, toxins • non-pathogens: cancer cells, transplanted tissue, pollen “self” “foreign”

10. Lymphocytes bone marrow • B cells • mature in bone marrow • humoral response system • attack pathogens still circulating in blood & lymph (liquids) • produce antibodies • T cells • mature in thymus • Cell mediated system • attack invaded cells - Tens of millions of different T cells are produced, each one specializing in the recognition of one particular antigen. T cells are responsible for disease resistance. • We’ll hit these more in a few slides!

11. B cells (from Bone marrow) s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s s • Attack, learn & remember pathogens circulating in blood & lymph • Produce specific antibodiesagainst specific antigen • Antibodies = Proteins that bind to a specific antigen • multi-chain proteins (2 heavy 2 light) • binding region matches molecular shape of antigens • each antibody is unique & specific • millions of antibodies respond to millions of foreign antigens

12. What do antibodies do to invaders? 4 ways they aid in immunity (#15) Y Y Y Y Y Y invading pathogens tagged with antibodies macrophageeating tagged invaders neutralize capture precipitate apoptosis

13. Vaccinations • Immune system exposed to harmless version of pathogen • stimulates B cell system to produce antibodies to pathogen • “active immunity” • rapid response on future exposure • creates immunity without getting disease! • Most successful against viruses

14. Passive immunity • Obtaining antibodies from another individual • maternal immunity • antibodies pass from mother to baby across placenta or in mother’s milk • critical role of breastfeeding in infant health • mother is creating antibodies against pathogens baby is being exposed to • Injection • injection of antibodies (Rabies,?Ebola) • short-term immunity (few weeks to months)

15. How is any cell tagged with antigens? MHC protein T or Bcell MHC proteins displaying self-antigens • Major histocompatibility (MHC) proteins • proteins which constantly carry bits of cellular material from the cytosol to the cell surface • “snapshot” of what is going on inside cell • give the surface of cells a unique label or “fingerprint” Who goes there? self or foreign?

16. T cells • Attack, learn & remember pathogens hiding in infected cells • recognize antigen fragments • also defend against “non-self” body cells • cancer & transplant cells • Types of T cells • helper T cells • Helper T cells detect infection and get the other cells of the immune system ready to do battle. Helper T cells also tell B cells to produce antibodies. • killer (cytotoxic) T cells • attack infected body cells • surpressor T cells • Turns off when no antigen is present T cell attacking cancer cell

17. HIV & AIDS • Human Immunodeficiency Virus • virus infects helper T cells • helper T cells don’t activate rest of immune system: killer T cells & B cells • also destroys helper T cells • AIDS: Acquired ImmunoDeficiencySyndrome • infections by opportunistic diseases • death usually from “opportunistic” infections that most people can fight • pneumonia, cancers HIV infected T cell

18. 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, dust mites, in animal saliva • stimulates release of histamine causing sneezing, runny nose, watery eyes and even death if system drops in blood pressure (epi pen)

19. Make sure you can do the following: • Explain the interplay between the humoral (antibodies from B cells, in blood), and cell-mediated responses (helper & killer T’s, macrophages - cells) http://www.youtube.com/watch?v=1tBOmG0QMbA • Demonstrate how the HIV virus leads to a breakdown of the immune system. • Explain why a vaccine works. • Explain the causes of immune system disruptions and how these disruptions can lead to disruptions of homeostasis.