The Immune & Lymphatic System, Ch.22

1. The Immune & Lymphatic System, Ch.22 • Types of Defense • ________________________: Innate defenses • Present at birth and provide immediate protection • 1st line of defense: skin and mucous membranes • 2nd line of defense: internal defenses • ________________________: Immunity • ______________ • ______________

2. Nonspecific Defense Mechanisms • Physical barriers • Chemical barriers • Increase in body temperature • Production of antimicrobial proteins • Inflammatory response

3. First line: skin & mucous membranes • Physical and chemical barriers: • Epidermis • Skin =barrier, & when sheds will remove microbes • Invade adjacent tissues & circulation thru cuts • Mucus- traps microbes • Hair, cilia • Lacrimal apparatus- tears contain lysozyme • Lysozyme found in: tears, perspiration, nasal secretions, & tissue fluids • Urine, vaginal secretions, defecation, vomit • Acidic: sebum, perspiration, gastric juice, vaginal secretions

4. Second line: Internal defenses • Antimicrobial proteins: • Interferons (IFN)- virus infected cells produce anti-viral proteins, communicate to uninfected cells • Complement system- enhance immune, cytolysis, phagocytosis, inflammation • Transferrins- inhibit bacterial growth • Natural Killer Cells & phagocytes • Inflammation • Fever: • ↑ temp due to reset hypothalamic thermostat • Intensifies IFN, microbes, speed up repair

6. Natural Killer Cells • NKC = 5-10% of lymphocytes in blood • Spleen, lymph nodes, RBM • Lack molecules to identify T & B cells • Ability to kill variety of infected & tumor cells • Attack cell w/abnormal MHC • Bind • Release granules of toxic substance • Perforin  cytolysis • Granzymes induce apoptosis or self-destruction • Kills cell but NOT MICROBES inside cell • Microbes need to be phagocytized

7. Phagocytes • Phagocytosis (part of Specific Immunity): • Neutrophils • __________________  wandering macrophages • Fixed macrophages stay put • Histiocytes, Kupffer cells, alveolar, microglia, and tissue macrophages in spleen, lymph nodes, & RBM • 5 phases: • _________________ • Adherence • Ingestion • Digestion • Killing

9. Inflammatory response fig 22.10 • Causes: pathogens (bacteria, virus), abrasions, chemical irritations, disturbances of cells, extreme temperatures, burns, radiation • 4 signs & symptoms: • ______________ • ______________ • ______________ • ______________ • Can also cause loss of function depending upon site and extent of injury:

10. Inflammatory response (2) • Purpose: attempt to dispose of microbes, toxins, foreign substances • Prevents spread of above • Prepare for repair and restoration • 3 Stages of inflammation: • Vasodilation & ↑ bv permeability • Emigration of phagocytes • Tissue repair

12. Vasodilation & ↑ permeability • Vasodilation  ↑ blood flow to area • Remove microbial toxins, dead cells • ↑ permeability  proteins & clotting factors • Substances responsible: • Histamine • Kinins • Prostaglandins • Leukotrienes • Complement

15. 1. When a localized area exhibits increased capillary filtration and swelling, this is an indication that • A. an immune response is underway • B. fever is developing • C. inflammation is occurring • D. Ab are phagocytizing target cells • E. fever is ending

16. 2. Which type of molecule is produced by viral-infected cells to communicate to non-infected cells of the presence of a virus? • A. Complement • B. Interferon • C. Pyrogen • D. Antigen • E. Antibodies

17. 3. Saliva and tears contain this enzyme that destroys bacteria. • A. Trypsin • B. Amylase • C. Lysozyme • D. Salivase • E. Kinase

18. Specific resistance: Immunity • Specificity and memory • Humoral or antibody-mediated (AMI) • _________________ into plasma cells  synthesize & ___________ or immunoglobulins • Antibody bind and inactivates its antigen • Cell- mediated (CMI) • _______________ proliferate into cytotoxic T cells that ______________ the invading antigen

19. T cell populations • Cytotoxic T cells: • Kill infected cells and cancer cells • Helper T cells: • Secrete __________________- help regulate B cells and T cells,  play a pivotal role in BOTH humoral & cell mediated responses • Secrete protein factors and molecules secreted to regulate neighboring cells • Memory T cells: • Remain from proliferated clone after CM response

21. Cell mediated immunity • Activation of T cells by specific antigen • T cell proliferation & differentiation into clone of effector cells • Elimination – ________________  cytolysis • Specific to specific antigens • Can leave lymph tissue to seek and destroy foreign antigens

22. Antibody-mediated response • _______________________ • ________ responds to _____________ antigen • Stay in lymph tissue: nodes,spleen,MALT • Activated upon presence of foreign antigen • Differentiate into plasma cells • Produce antibodies • Ab circulate in lymph and blood to reach invasion site • Some B cells become ____________________

23. Ab-mediated response • Inactive B cell receptor binds antigen, can stimulate T cell to intensify response • Plasma cells develop and produce Ab • Memory cells develop and remain to respond to antigen in the future

25. Production of antibodies

28. 4. A "foreign" molecule which can invoke the immune response is called a(n) • A. Antigen • B. Immunoglobulin • C. Hapten • D. Antibody • E. Histamine

29. 5. The immune cell that allows for subsequent recognition of an antigen resulting in a secondary response is called a(n) • A. helper T-cell • B. memory cell • C. antigen-presenting cell • D. plasma cell • E. macrophage

30. 6. Active, artificially acquired immunity is a result of • A. Vaccination • B. Ab passed from mother to fetus through the placenta • C. Ab passed from mother to baby through breast milk • D. injection of immune serum • E. Ab produced due to previous exposure to an antigen

31. Clinical Connections • Organ transplants- rejection dependent upon similarity of MHCs • Immunodeficiency- as in HIV, lose helper T cells, opportunistic infections may occur • Autoimmune diseases- fail to display self tolerance and attack own tissues • Hypersensitivity- allergic rxn to things that most people tolerate (4 types)

32. 7. Cytotoxic T cells kill target cells • A. through insertion of perforins into the target's membrane • B. by secreting antibodies • C. by phagocytosis • D. through injection of tumor necrosis factor • E. Causing an inflammatory response

33. 8. Lymphocytes that develop immunocompetence in the thymus are • A. neutrophils • B. T lymphocytes • C. B lymphocytes • D. Basophils • E. Eosinophils

34. 9. This type of disease results from the inability of the immune system to distinguish self from non-self antigens: • A. Allergy • B. Immunodeficiency • C. Anaphylaxis • D. Autoimmune disease • E. Inflammatory response

35. The Lymphatic System • Vessels • Primary lymphatic organs • Red bone marrow • Thymus • Secondary lymph organs and tissue • Lymph nodes • Spleen • Lymph nodules (tissue because lacks capsule)

37. Functions of the Lymphatic System • Draining excess interstitial fluid • ______________ = interstitial fluid that has passed into a lymph vessel • Transporting dietary lipids • Lacteals-- GI tract to blood • Protecting against invasion through immune responses • Lymphatic tissue = specialized reticular CT with many lymphocytes

38. Lymphatic vessels, fig 22.2

39. Lymphatic vessels • Begin as lymph capillaries • Spaces between cells, closed one end • Unite to form larger vessels • Lymph vessels resemble veins but • Are thinner • Have more valves • Intervals along vessels: lymph nodes w/masses of T cells & B cells

40. Lymphatic vessels (2) • In skin: lie in subQ, follow same general route as veins • Viscera: generally follow arteries forming plexuses around them • Avascular tissue: often lack lymphatic capillaries • Cartilage, epidermis, cornea, CNS, spleen, RBM

41. Lymph capillaries • Slightly larger than blood capillaries • have a unique structure: interstitial fluid can flow in but not out • endothelial cells in wall overlap BUT: • when pressure is greater in interstitial fluid than in lymph, cells separate slightly • one-way valve opening, fluid enters • when pressure greater capillary, closed & lymph cannot flow out

42. Lymph capillaries (2) • Anchoring filaments- contain elastic fibers, attach lymphatic endothelial cells to surrounding tissues • When excess interstitial fluid accumulates, tissue swells filaments are pulled, opening larger for fluid to enter • Lacteals- specialized lymph capillaries in small intestine • Carry dietary lipids lymph vesselsblood • Chlye- lipids present in lymph

45. Lymph formation and flow • Most components of plasma can filter freely to form interstitial fluid • More out than back in  lymph returns this fluid • Excess filtered fluid≈ 3L/day=lymph • Small amt of proteins (most plasma proteins too large) • Proteins don’t easily diffuse backlymph important • Valves for one way movement • Skeletal and respiratory pumps (as veins)

46. Lymph nodes • ≈ 600 scattered throughout body • superficial and deep, usually in groups • however, high concentration in • Mammary gland • Axillae • Groin • Function as filters • Foreign substances trapped by reticular fibers within sinuses • Macrophages destroy by phagocytosis • Lymphocytes destroy by immune responses

49. Flow thru nodes is unidirectional • Afferent lymphatic vessels  • valves of node  • subcapsular sinus  • trabecular sinuses (cortex)  • medullary sinuses  • one of 2 efferent lymph vessels  • valves  • hilum = also where bv enter and leave

50. Primary (1°) lymphatic organs • Where stem cells divide & become immunocompetent • Red Bone Marrow • Thymus • Stem cells divide & mature into • B cells – red bone marrow • T cells - thymus