Chapter 23 Immune System

1. Chapter 23 Immune System

2. What You’ll Learn You will describe how infections are transmitted and what causes the symptoms of diseases. You will explain the various types of innate and acquired immune responses. • You will compare antibody and cellular immunity

3. 23.1 Infectious diseases • Section Objectives: • Describe how pathogens are transmitted. • Explain what causes the symptoms of a disease.

4. What is an infectious disease? • Disease-producing agents such as bacteria, protozoans, fungi, viruses, and other parasites are called pathogens. (NOT all microorganisms are pathogens • main sources of pathogens are soil, contaminated water, and infected animals, including other people.

5. Reservoirs of pathogens

6. Transmission of disease • Pathogens can be transmitted to a host from reservoirs in four main ways: by direct contact, by an object, through the air, or by an intermediate organism called a vector.

7. Transmission of disease II • The common cold, influenza, and STDs are spread by direct contact.

8. Transmission of disease III • Bacteria and other microorganisms can be present on nonliving objects such as money, toys, or towels. • Transmission occurs when people unknowingly handle contaminated objects.

9. Transmission of disease IV • Airborne transmission of a disease can occur when a person coughs or sneezes, spreading pathogens contained in droplets of mucus into the air.

10. Transmission of disease V • Diseases transmitted by vectors are most commonly spread by insects and arthropods • malaria and the West Nile virus are transmitted by mosquitoes. • Lyme disease and Rocky Mountain spotted fever are diseases that are transmitted by ticks. • Flies also are significant vectors of disease.

11. What causes the symptoms of a disease? • When a pathogen invades your body, it encounters your immune system. • If the pathogen overcomes the defenses of your immune system, it can metabolize and multiply, causing damage to the tissues it has invaded, and even killing host cells

12. Damage to the host by viruses and bacteria • Most of the damage done to host cells by bacteria is inflicted by toxins. • These poisons can inhibit protein synthesis in the host cell, destroy blood cells and blood vessels, produce fever, or cause spasms by disrupting the nervous system.

13. Patterns of Diseases • Some diseases, such as typhoid fever, occur only occasionally in the United States. • On the other hand, many diseases are constantly present in the population-endemic disease. Ex. Common cold

14. Treating Diseases • 1 way: An antibiotic is a substance produced by a microorganism that, in small amounts, will kill or inhibit the growth and reproduction of bacteria. • Your body also has its own built-in defense system— the immune system —that works to keep you healthy.

15. 23.2 The Immune System • Section Objectives: • Identify the cells, tissues, and organs that make up the immune system. • Compare innate( nonspecific) and acquired (specific)immune responses. • Distinguish between antibody and cellular immunity. • Summarize the structure of the lymphatic system • Distiguish between passive and active immunity

16. Lines of defense Barriers • 1st line: • broad, external defense • “walls & moats” • skin & mucus membranes • 2nd line: • broad, internal defense • “patrolling soldiers” • phagocyte (eating) WBCs • 3rd line: • specific, acquired immunity • “elite trained units” • lymphocyte WBCs & antibodies • B & T cells Non-specific patrol Immune system

17. Innate Immunity • The body’s earliest lines of defense against any and all pathogens make up your nonspecific, innate immunity.

18. Nonspecific defense I Lining of trachea: ciliated cells & mucus secreting cells • 1st line of defense: • Skin Intact skin is a formidable physical barrier to the entrance of microorganisms • Body secretions mucus traps many microorganisms • Sweat, tears, and saliva all contain the enzyme lysozyme, which is capable of breaking down the cell walls of some bacteria

19. Nonspecific defense II • 2nd line of defense • Inflammation(Inflammatory response) characterized by four symptoms—redness, swelling, pain, and heat; histamine released causes blood vessels in the injured area to dilate,(redness) which makes them more permeable to tissue fluid. Fluid that leaks from the vessels helps the body destroy toxic agents and restore homeostasis (swelling and pain,&heat)

20. Nonspecific defense V Swelling occurs Tissue fluid moves into injured area • After a few days, infected tissue harbors a collection of live and dead white blood cells, multiplying and dead pathogens, and body fluids called pus. • Pus formation usually continues until the infection subsides. • Eventually, the pus is cleared away by macrophages. Phagocytes Pus

21. Nonspecific defense III • 2nd line of defense Phagocytosis of pathogens white blood cells that destroy pathogens by surrounding and engulfing them. • Macrophages are white blood cells that provide the first defense against pathogens that have managed to enter the tissues. Macrophage “eating” bacteria

22. Phagocytes macrophage bacteria white blood cells that eat macrophage yeast

23. Fever • When a local response is not enough • full body response to infection • raises body temperature • higher temperature helps in defense • slows growth of germs • helps macrophages • speeds up repair of tissues

24. Nonspecific defense IV • Phagocytosis of pathogens • If the infection is not stopped by the tissue macrophages, another type of phagocyte, called a neutrophil is attracted to the site. • If the infection is not stopped by tissue macrophages and neutrophils - Monocytes

25. Nonspecific defense VI • Protective proteins: • Interferons are proteins that protect cells from viruses. • Complement: help attract phagocytes to foreign cells and help destroy foreign cells • Natural Killer cells:type of white blood cell that destroy the body's own infected cells, may attack cells that form tumors

26. The lymphatic system • The lymphatic system becomes a crucial battleground during infection • a network of lymphatic vessels and organs • It returns tissue fluid to the circulatory system • It fights infections • Lymph nodes are key sites for fighting infection • They are packed with lymphocytes and macrophages

27. Acquired Immunity • Defending against a specific pathogen by gradually building up a resistance to it • This acquired immune response enables these white blood cells to inactivate or destroy the pathogen. • Acquired immunity involves the production of two kinds of immune responses: antibody immunity and cellular immunity ~ • your 3rd line of defense

28. Acquired Immunity • SPECIFIC IMMUNITY • IMMUNE RESPONSE arecognition system that distinguishes “self” from “non-self” • responds to foreign molecules called antigens • Stimulates the body to make antibodies: specific defensive proteins which help to counter antigens in various ways

29. How are invaders recognized? • Antigens • chemical name tags on the surface of every cell • “self” vs. “invader” disease-causingbacteria one of yourown cells disease-causingvirus antigens say:“I am an invader” antigens say:“I belong here” antigens say:“I am an invader”

30. 3rd line of defenseLymphocytes ~type of white blood cell that carry out the immune response B lymphocyte • Two kinds • B cells secrete antibodies that attack antigens (antibody immunity) • T cells attack cells infected with pathogens (cellular immunity)

31. B cells & antibodies • B cells • white blood cells that attack invaders in blood • mature in Bone marrow • Patrolling B cells • make antibodies against invader immediately • Memory B cells • remembers invader • can make antibodies quickly the next time • protects you from getting disease more than once

32. Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Antibodies • Proteins made by B cells that tag invaders in the blood so macrophages can eat them • tag says “this is an invader”  gotcha! • biological “handcuffs” • antibody attaches to antigen of invader invading germs tagged with antibodies B cells releasing antibodies Y macrophageeating tagged invaders

33. Antibody Immunity • An antibody molecule has antigen-binding sites specific to the antigen • Do not posses the power to destroy antigens directly, tag and mark them for destruction by a variety of mechanisms

34. Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y B cells Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y release antibodies patrol blood forever Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y B cells Y Y Y Y Y Y memory B cells Y Y Y “reserves” Y Y Y Y Y Y Y Y B cells immune response invader(foreign antigen) recognition 10 to 17 days

35. T cells • T cells mature in Thymus • Helper T cells • sound the alarm for rest of immune system • Killer T cells • destroy infected body cells • Memory T cells • remembers invader & reacts against it again quickly Where’s that?

36. Attack of the Killer T cells • Killer T cells destroy infected body cells • T cell binds to invaded cell • secretes perforating protein • punctures cell membrane of infected cell • cell bursts Killer T cell vesicle Perforinpuncturescell membrane cell membrane cell membrane invaded cell

37. T What if the attacker gets past the B cells in the blood &infects some of your cells? You need trained assassins to kill off these infected cells! Attackof the Killer T cells!

38. Cellular Immunity Infected cells Perforin Pathogen engulfed by Foreign antigen Infected cell lyses Macrophage Cytotoxic T cell Displays antigens on surface and stimulates T cell Attacks infected cell Stimulates Cytotoxic T cell Helper T cell

39. Y Y Y Y Y Y Y Y Y Y Y Y Y Y antibodies antibodies Y Y Y Y Y Y Y Y Immune response invader skin skin invaders in body invaders in blood invaders infect cells macrophages helperT cells B cells T cells patrollingB cells memoryB cells memoryT cells killerT cells

40. Passive and Active Immunity • Acquired immunity to a disease may be either passive or active.

41. Passive Immunity Passive: short term, antibodies passed on, not stimulated by antigens, acquired naturally by placenta or breast milk or artificially acquired by a shot

42. Active Immunity • Active: long term, conferred by actual encounter with infection (naturally acquired) or vaccination *(artificially acquired) * vaccine~ substance consisting of weakened, dead, ,or parts of pathogen or antigen that when injected , stimulates the immune system

43. 23.3 Noninfectious disorders Section objective: Describe categories od noninfectious disease

44. Noninfectious disorders Genetic disorders • Caused by the inheritance of genes that do not function properly • ex: sickle cell anemia, hemophilia, cystic fibrosis

45. Noninfectious disorders • Degenerative diseases~ result of a part of the body wearing out ex: degenerative arthritis • Metabolic diseases~ results in an error in a biochemical pathway • Cancer~ abnormal cell growth

46. DISORDERS OF THE IMMUNE SYSTEM • Allergies are overreactions to certain environmental antigens called allergens : Ex. Animal dander, dust mites, pollen release of histamine causes symptoms:sneezing, increased mucus production in the nasal passages, and redness. Antihistamines can relieve symptoms

47. DISORDERS OF THE IMMUNE SYSTEM Rheumatoid arthritis • Autoimmune diseases immune system also can mistakenly attack the body’s own tissues • Examples: Rheumatic fever, Type I Diabetes, Multiple Sclerosis, Rheumatoid arthritis, Lupus

48. DISORDERS OF THE IMMUNE SYSTEM HIV on a lymphocyte • Immunodeficiency diseases • Immune components are lacking, and infections recur Ex: Acquired immune deficiency syndrome (AIDS) SCIDS

49. AIDS • HIV (Human Immunodeficiency Virus) the virus that causes AIDS • HIV is transmitted mainly in blood and semen • HIV kills helper T-cells and leads to AIDS

50. Attacking transplanted tissue. • T cells and antibodies also can attack transplanted tissue, such as a transplanted kidney, that comes from a source outside the body.