1. Chapter 47 Table of Contents Section 1 Nonspecific Defenses
The Body’s Defense Systems
Table of Contents
Section 1 Nonspecific Defenses
Section 2 Specific Defenses: The Immune System
Section 3 HIV and AIDS

2. Section 1 Nonspecific Defenses
Chapter 47
Objectives
Summarize Koch’s postulates for identifying a disease-causing agent.
Describe how the skin and mucous membranes protect the body against pathogens.
Describe the steps of the inflammatory response.
Analyze the roles of white blood cells in fighting pathogens.
Explain the functions of fever and proteins in fighting pathogens.

3. Identifying Pathogens
Section 1 Nonspecific Defenses
Chapter 47
Identifying Pathogens
A pathogen is any agent that causes disease and can be spread to humans through the air, food, water, or direct contact with an infected animal or person.
A disease that is caused by a pathogenic bacteria, virus, fungi, or protist is called an infectious disease.
Koch’s postulates are “rules” for identifying the particular pathogen that causes a specific disease.

4. Chapter 47 Pathogen Section 1 Nonspecific Defenses
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5. Section 1 Nonspecific Defenses
Chapter 47
Koch’s Postulates

6. Chapter 47 Koch’s Postulates Section 1 Nonspecific Defenses
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7. First Line of Defense: Barriers
Section 1 Nonspecific Defenses
Chapter 47
First Line of Defense: Barriers
Nonspecific defenses, such as the skin and mucous membranes, are barriers to potential pathogens.
In addition to being a physical barrier to pathogens, skin also produces sweat, oils, and waxes, which are toxic to many bacteria.
A mucous membrane is a layer of epithelial tissue that covers internal surfaces of the body and secretes mucus, a sticky fluid that traps pathogens.

8. Second Line of Defense: Nonspecific Immunity
Section 1 Nonspecific Defenses
Chapter 47
Second Line of Defense: Nonspecific Immunity
If a pathogen gets past the skin and the mucous membranes, the body triggers the second line of defense, which is nonspecific immunity.
Nonspecific immunity works in the same way against any pathogen.
Nonspecific immunity includes the inflammatory response, the temperature response, and certain proteins.

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Section 1 Nonspecific Defenses
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Second Line of Defense: Nonspecific Immunity, continued
Inflammatory Response
An inflammatory response is a series of events that suppress infection and speed recovery.
When cells are damaged they release chemical messengers, such as histamine.
Histamine is a substance that increases blood flow to the injured area and increases the permeability of surrounding capillaries.

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Second Line of Defense: Nonspecific Immunity, continued
Inflammatory Response, continued
Fluids and white blood cells called phagocytes leak through capillary walls to fight any pathogens that may have entered the body.
Phagocytes are cells that ingest and destroy foreign matter, such as microorganisms.

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Second Line of Defense: Nonspecific Immunity, continued
Inflammatory Response, continued
The most common phagocyte in the body is called a neutrophil.
A neutrophil is a large leukocyte that contains a lobed nucleus and many cytoplasmic granules.

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Inflammatory Response, continued
A macrophage is a white blood cell that engulfs pathogens and other materials.
Another type of white blood cell that attacks pathogen-infected cells is called a natural killer cell.

13. Inflammatory Response
Section 1 Nonspecific Defenses
Chapter 47
Inflammatory Response

14. Inflammatory Response
Section 1 Nonspecific Defenses
Chapter 47
Inflammatory Response
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15. Second Line of Defense: Nonspecific Immunity, continued
Section 1 Nonspecific Defenses
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Second Line of Defense: Nonspecific Immunity, continued
Temperature Response
When the body begins to fight pathogens, body temperature may increase. This rise in temperature is called a fever.
The body triggers a fever in order to slow bacterial growth or to promote white blood cell activity.
Though a moderate fever can be helpful, high fevesr can be dangerous.

16. Fever as Nonspecific Defense
Section 1 Nonspecific Defenses
Chapter 47
Fever as Nonspecific Defense
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17. Second Line of Defense: Nonspecific Immunity, continued
Section 1 Nonspecific Defenses
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Second Line of Defense: Nonspecific Immunity, continued
Proteins
Proteins also provide nonspecific defenses.
The complement system is a system of proteins that circulate in the bloodstream and become active when they encounter certain pathogens.
Interferon is a protein released by cells infected with viruses that enables nearby cells to resist viral infection.

18. Section 2 Specific Defense: The Immune System
Chapter 47
Objectives
Identify and describe the parts of the immune system.
Explain how the immune system recognizes pathogens.
Compare the actions of T cells and B cells in the immune response.
Relate vaccination to immunity.
Distinguish between allergy, asthma, and autoimmune disease.

19. Chapter 47 The Immune System
Section 2 Specific Defense: The Immune System
Chapter 47
The Immune System
The immune system includes the cells and tissues that recognize and attack foreign substances in the body.
The components of the immune system are found throughout the body.

20. The Immune System, continued
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The Immune System, continued
Bone marrow, the thymus, lymph nodes, the spleen, adenoids, and tonsils are all part of the immune system.
Each part of the immune system plays a special role in defending the body against pathogens.
The specialized cells of the immune system are called lymphocytes. Lymphocytes are white blood cells that exists in two primary forms: T and B cells.

21. The Immune System, continued
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The Immune System, continued
B cells are white blood cells that are made in the bone marrow and complete their development there or in the spleen. B cells make antibodies.
T cells are cells that are made in the bone marrow but complete their development only after traveling to the thymus. T cells also participate in many immune reactions.

22. Recognizing Pathogens
Section 2 Specific Defense: The Immune System
Chapter 47
Recognizing Pathogens
Lymphocytes can provide specific defenses because they recognize pathogens by the antigens on their surface.
An antigen is any substance that the immune system does not recognize as part of the body.

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Recognizing Pathogens, continued
Because the lymphocytes do not recognize the antigen, they start a specific attack known as an immune response.
Lymphocytes recognize a pathogen with molecules on their surface called receptor proteins.

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Recognizing Pathogens, continued
An antigen has a complementary three-dimensional shape that allows the receptor protein to bind to it. This is how the lymphocyte recognizes the antigen.
Only the specific receptor protein that is complementary to the antigen will be able to bind there.

25. How a Cytotoxic T Cell Recognizes an Infected Cell
Section 2 Specific Defense: The Immune System
Chapter 47
How a Cytotoxic T Cell Recognizes an Infected Cell

26. Recognition of Pathogens
Section 2 Specific Defense: The Immune System
Chapter 47
Recognition of Pathogens
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27. Chapter 47 Immune Response
Section 2 Specific Defense: The Immune System
Chapter 47
Immune Response
An immune response is a two-part assault on a pathogen. Both parts occur at the same time and require a specialized lymphocyte called a helper T cell.
The two parts of the immune response are the cell-mediated immune response and the humoral immune response.
T cells activate certain proteins that affect the behavior of other immune cells. These proteins are called cytokines.

28. Immune Response, continued
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Immune Response, continued
Cell-Mediated Immune Response
In the cell-mediated immune response, cytokines activate more helper T cells and another type of T cell called a cytotoxic T cell.
Cytotoxic T cells recognize and destroy cells that have been infected by a pathogen.

29. Immune Response, continued
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Immune Response, continued
Cell-Mediated Immune Response, continued
Also produced during the cell-mediated immune response is a type of T cell called the suppressor T cell.
Suppressor T cells are thought to shut down the immune response after the pathogen has been cleared from the body.

30. Cell-Mediated Immune Response
Section 2 Specific Defense: The Immune System
Chapter 47
Cell-Mediated Immune Response
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31. Immune Response, continued
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Immune Response, continued
Humoral Immune Response
The humoral immune response involves the action of B cells and occurs when antibodies are activated within body fluids.
The humoral immune response occurs at the same time as the cell-mediated immune response.
During the humoral response, cytokines stimulate B cells that have receptors that are complementary to the antigen to divide and change.

32. Immune Response, continued
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Immune Response, continued
Humoral Immune Response, continued
Most B cells form plasma cells. A plasma cell is a white blood cell that produces antibodies.
Antibodies are defensive proteins that react to a specific antigen or inactivate or indirectly destroy toxins.
Antibodies use various methods to disable a pathogen or cause its destruction by nonspecific responses.

33. Immune Response, continued
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Immune Response, continued
Primary and Secondary Immune Responses
The first time the body encounters an antigen, the immune response is called a primary immune response.
During this first encounter, the immune system fights off the disease. After the disease is overcome, the immune system creates memory cells.
Memory cells are a B cell or T cell that will recognize and attack the antigen or invading cell during subsequent infections.

34. Immune Response, continued
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Immune Response, continued
Primary and Secondary Immune Responses, continued
The second time the body encounters an antigen, a secondary immune response occurs.
During a secondary immune response, the immune response is faster and more powerful.
Most of the time, the secondary immune response protects the body from reinfection by a pathogen.

35. Chapter 47 The Immune Response
Section 2 Specific Defense: The Immune System
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The Immune Response

36. The Immune Response, continued
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The Immune Response, continued

37. Primary and Secondary Immune Responses
Section 2 Specific Defense: The Immune System
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Primary and Secondary Immune Responses

38. Primary and Secondary Immune Response
Section 2 Specific Defense: The Immune System
Chapter 47
Primary and Secondary Immune Response
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39. Immunity and Vaccination
Section 2 Specific Defense: The Immune System
Chapter 47
Immunity and Vaccination
Immunity is the ability to resist an infectious disease.
Immunity can come about in two ways: surviving an initial infection or through vaccination.
Vaccination is the introduction of antigens into the body to cause immunity.

40. Immunity and Vaccination, continued
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Immunity and Vaccination, continued
Vaccines
Vaccination usually involves an injection of a vaccine.
A vaccine is a solution that contains a dead or weakened pathogen or material from a pathogen that still contains antigens.
The immune system will produce a primary immune response to the antigens. Memory cells can then provide a quick secondary immune response if the antigen ever enters the body again.

41. Chapter 47 Vaccine Section 2 Specific Defense: The Immune System
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42. Problems of the Immune System
Section 2 Specific Defense: The Immune System
Chapter 47
Problems of the Immune System
Sometimes the immune system can react to harmless antigens. Three examples of this are allergies, asthma, and autoimmune diseases.
Allergies
An allergy is a physical response to an antigen, which can be a common substance that produces little or no response in the general population.

43. Problems of the Immune System
Section 2 Specific Defense: The Immune System
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Problems of the Immune System
Asthma
Allergies can trigger asthma. Asthma is a respiratory disorder that causes the bronchioles to narrow due to an overreaction to substances in the air.
During an asthma attack, the lining of the bronchioles and other respiratory tissues may also swell and become inflamed.

44. Problems of the Immune System
Section 2 Specific Defense: The Immune System
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Problems of the Immune System
AIDS (acquired immunodeficiency syndrome) is a disease caused by HIV (human immunodeficiency virus).
Infection by HIV causes the immune system to lose its ability to fight off pathogens and cancers.
HIV infection usually progresses to AIDS in three phases.

45. Chapter 47 Objectives Describe the relationship between HIV and AIDS.
Section 3 HIV and AIDS
Chapter 47
Objectives
Describe the relationship between HIV and AIDS.
Distinguish between the three phases of HIV infection.
Identify the two main ways that HIV is transmitted.
Determine how the evolution of HIV affects the development of vaccines and treatment.

46. The Course of HIV Infection
Section 3 HIV and AIDS
Chapter 47
The Course of HIV Infection
AIDS (acquired immunodeficiency syndrome) is a disease caused by HIV (human immunodeficiency virus).
Infection by HIV causes the immune system to lose its ability to fight off pathogens and cancers.
HIV infection usually progresses to AIDS in three phases.

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The Course of HIV Infection, continued
Phase I
Phase I of HIV infection is called the asymptomatic stage, because there are few or no symptoms of the disease.
During this period of the disease the viruses increase rapidly due to replication.
Phase I can last up to 10 years or more.

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The Course of HIV Infection, continued
Phase II
The beginning or worsening of symptoms marks the start of the second phase of HIV infection.
B cells continue making antibodies, but T cells begin to decline steadily as the virus continues to replicate.

49. The Course of HIV Infection, continued
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The Course of HIV Infection, continued
Phase III
Phase III of HIV infection is the point where the number of helper T cells drops so low that they can no longer stimulate B cells and cytotoxic T cells to fight invaders.
AIDS is diagnosed when the helper T-cell count drops below a certain level.

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The Course of HIV Infection, continued
Phase III, continued
AIDS is also diagnosed if an opportunistic infection has developed.
Opportunistic infections are illnesses caused by pathogens that produce disease in people with weakened immune systems. These organisms usually do not creat problems in people with a healthy immune system.
Drug therapy can slow the progress of HIV infection to AIDS, but there is no cure for AIDS.

51. Course of HIV Infection
Section 3 HIV and AIDS
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Course of HIV Infection

52. Chapter 47 Transmission of HIV
Section 3 HIV and AIDS
Chapter 47
Transmission of HIV
HIV is transmitted by the transfer of body fluids containing HIV or HIV-infected cells.
This most commonly occurs by sexual contact with an infected person or by use of syringes and hypodermic needles that have been contaminated with blood containing HIV.
HIV cannot be transmitted through casual contact.

53. Known Routes of HIV Transmission
Section 3 HIV and AIDS
Chapter 47
Known Routes of HIV Transmission

54. Course of an HIV Infection
Section 3 HIV and AIDS
Chapter 47
Course of an HIV Infection
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55. Vaccines and Treatments
Section 3 HIV and AIDS
Chapter 47
Vaccines and Treatments
Effective treatments and vaccines for HIV are difficult to create, because HIV has a rapid evolution rate.
Treatment is also difficult because HIV quickly becomes resistant to antiviral drugs.
Most HIV treatments are expensive and require a complicated multidrug therapy.

56. Chapter 47 Spread of AIDS Section 3 HIV and AIDS
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