Opening Activity. Make a list of all the diseases and infections you have had.

Transcription

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2 Opening Activity Make a list of all the diseases and infections you have had. If you have had chicken pox, indicate whether you have had it more than once.

3 Content Objectives I will be able to identify how the specific immune response is activated? I will be able to identify how the body eliminates intracellular pathogens? I will be able to identify how the body eliminates extracellular pathogens? I will be able to identify how the immune system protects the body from repeated infection by the same pathogen?

4 Chapter 37 Section 2: Eliminating Invaders Key Vocabulary Terms Adapted from Holt Biology 2008

5 B Cell A white blood cell that matures in bones and makes antibodies Adapted from Holt Biology 2008

6 Helper T Cell A white blood cell necessary for B cells to develop normal levels of antibodies Adapted from Holt Biology 2008

7 A type of T cell that recognizes and destroys cells infected by virus Cytotoxic T Cell Adapted from Holt Biology 2008

8 A protein that reacts to a specific antigen or that inactivates or destroys toxins Antibody Adapted from Holt Biology 2008

9 A substance that stimulates an immune response Plasma Cell Adapted from Holt Biology 2008

10 Memory Cell An immune system B cell or T cell that does not respond the first time that it meets with an antigen or an invading cell but that recognizes and attacks the antigen or invading cell during subsequent infections Adapted from Holt Biology 2008

11 Immunity The ability to resist or recover from an infectious disease Adapted from Holt Biology 2008

12 YOUR TURN With a partner, read Chapter 37 Section 2 Active Reading (Eliminating Invaders). Take turns reading the questions aloud to each other, alternating questions. Read the paragraphs aloud, alternating paragraphs. Adapted from Holt Biology 2008

13 YOUR TURN Discuss what you have read! From your discussion write the best possible response to the questions. Be prepared to share with the class. 2 Adapted from Holt Biology 2008 Adapted from Holt Biology 2008

14 THINK, SHARE, & WRITE #1 Which Cells produce antibodies?

15 THINK, SHARE, & WRITE Which Cells produce antibodies? Plasma Cells

16 Activating a Specific Immune Response The immune system consists of many types of white blood cells, including macrophages, T cells, and B cells.

17 Activating a Specific Immune Response When a macrophage engulfs and destroys a pathogen, the antigen is displayed on the surface of the macrophage. These antigen-displaying macrophages activate helper T cells.

18 Content Objectives I will be able to identify how the specific immune response is activated? I will be able to identify how the body eliminates intracellular pathogens? I will be able to identify how the body eliminates extracellular pathogens? I will be able to identify how the immune system protects the body from repeated infection by the same pathogen?

19 Activating a Specific Immune Response Helper T cells are specialized white blood cells that activates the immune system. They regulate the function of other cells in the immune system.

20 The Immune Response System Click to animate the image.

21 Activating a Specific Immune Response Helper T cells coordinate two responses: destroying cells that have been infected by a pathogen, and cleaning up pathogens at large in the body.

22 Activating a Specific Immune Response Helper T cells have specific antigen receptors on their surfaces that bind to specific antigens that are displayed on the surface of a macrophage.

23 Activating a Specific Immune Response Helper T cells are activated when their receptors bind to antigens. Activated helper T cells grow and divide to produce more helper T cells that have identical receptors on their surfaces.

24 Destroying Infected Cells Helper T cells do not directly attack infected body cells or pathogens. Instead, they produce chemical signals that activate the second kind of T cell, called cytotoxic T cells.

25 Destroying Infected Cells Cytotoxic T cells are white blood cells that carry pathogen-specific receptors on their surfaces.

26 Destroying Infected Cells Cytotoxic T cells attack and kill cells that have been infected by pathogens.

27 Destroying Infected Cells Activated helper T cells turn on the production of cytotoxic T cells that have the same antigen receptor.

28 Destroying Infected Cells The new cytotoxic T cells bind to matching antigens on the surface of infected cells.

29 Destroying Infected Cells, continued When they bind, the cytotoxic T cells release chemicals that punch holes in the membranes of the infected cells.

30 Destroying Infected Cells The infected cells die when water enters through the holes and splits them open.

31 Removing Pathogens at Large Helper T cells also activate B cells. B cells are white blood cells that produce proteins that bind to pathogens outside of body cells.

32 Removing Pathogens at Large The B cell response removes extracellular pathogens from the body and prevents further infection.

33 Removing Pathogens at Large Activated B cells produce white blood cells plasma cells, which produce and release antibodies.

34 Removing Pathogens at Large Antibodies are Y- shaped protein molecules that bind to the specific antigen that they match.

35 Removing Pathogens at Large Each Y-shaped antibody has two binding sites which are located at the tips of the Y s.

36 Removing Pathogens at Large Antibodies circulate in the blood and lymph fluid, binding to pathogens with the specific antigen that they match.

37 Removing Pathogens at Large The binding of multiple antibodies to pathogens forms an antigen-antibody complex.

38 Removing Pathogens at Large These antigenantibody complexes are then destroyed by general defense mechanisms, such as macrophages or defense proteins.

39 The Immune Response System Click to animate the image.

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41 Content Objectives I will be able to identify how the specific immune response is activated? I will be able to identify how the body eliminates intracellular pathogens? I will be able to identify how the body eliminates extracellular pathogens? I will be able to identify how the immune system protects the body from repeated infection by the same pathogen?

42 Long-Term Protection In addition to plasma cells, activated B cells also produce another type of white blood cell called a memory cell.

43 Long-Term Protection Memory cells carry antigen receptors which recognize the target antigen. If the same pathogen invades the body again, the memory cells rapidly launch an immune response.

44 Long-Term Protection After an immune response, memory cells continue to protect the body from previously encountered pathogens.

45 An individual who recovers from an infectious disease becomes resistant to that particular pathogen. Long-Term Protection

46 Long-Term Protection The secondary immune response that is initiated by memory cells is called immunity. Immunity is a longlasting resistance that is usually effective only against the specific pathogen that triggered the response.

47 Long-Term Protection Immunity can be acquired without infection through the use of vaccines. A vaccine is a solution that contains a dead or weakened form of a pathogen which is typically injected into the bloodstream.

48 Long-Term Protection Vaccines trigger the immune response to form memory cells against the pathogen.

49 Long-Term Protection Changes in the genetic material of a microorganism can occur frequently. These genetic changes may cause antigen shifting, an abrupt change in a pathogen s antigens.

50 Long-Term Protection, continued Antigen shifting can enable a pathogen to evade recognition by the immune system of a person who has previously had immunity against the pathogen.

51 Long-Term Protection, continued Influenza viruses are well known for frequent antigen shifting.

52 THINK, SHARE, & WRITE #1 What causes antigen Shifting?

53 THINK, SHARE, & WRITE What causes antigen Shifting? Antigen shifting is caused by the mutation of viral cells.

54 Summary A specialized white blood cell called a helper T cell activates the immune system. These cells coordinate two responses: destroying cells that have been infected by a pathogen, and cleaning up pathogens at large in the body.

55 Cytotoxic (Killer) T cells attack and kill cells that have been infected by pathogens. Summary

56 Summary The B cell response removes extracellular pathogens from the body and prevents further infection.

57 Summary After an immune response, memory cells continue to protect the body from previously encountered pathogens. An individual who recovers from an infectious disease becomes resistant to that particular pathogen.