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The Immune System A white blood cell eating bacteria. Small Pox.

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Presentation on theme: "The Immune System A white blood cell eating bacteria. Small Pox."— Presentation transcript:

1 The Immune System A white blood cell eating bacteria. Small Pox

2 The Immune System 1.The immune system is a defense system against foreign invaders (pathogens) 2.Immune system consists of a variety of different types of white blood cells (WBC’s) White blood cell eating bacteria Slide # 2

3 The SKIN: The First Line of Defense 1. The skin is the most important first line of defense a. Top layer is dead cells; prevents pathogens from entering b. Sweat & tears have enzymes that prevent bacterial growth 2. Mucus that lines the nose, throat, & lungs traps pathogens 3. Pathogens and mucus are swept into stomach where stomach acids destroy them Slide # 3 Layers of Skin

4 Inflammatory Response: Second line of Defense 1.Nonspecific response to a localized infection. 2.Injured or infected cells cause blood vessels to enlarge so they can leak fluid & WBC’s a. skin appears red at injury site b. swelling occurs around infection 3. Macrophages (large WBC’s are first to arrive) a. Nonspecific: treat all pathogens the same b. Consume (eat) dead cells & pathogens 4. Fever kills pathogens. Fever over 103°F is dangerous for humans. Slide # 4

5 White blood cell chasing a bacterium cell Click on the picture to watch!

6 Skin Wound Bacteria enter the wound Phagocytes move into the area and engulf the bacteria and cell debris Capillary The Inflammatory Response Slide # 6

7 The Immune Response: Vocabulary 1. Immunity: capacity of the human body to resist specific pathogens by identifying foreign (non-self) antigens 2. Antigen: anything that causes an immune response 3. Lymphocytes: WBC’s involved in immunity and the immune response a. Helper T cells, B cells, & Killer T cells b. are specific; seek out & destroy specific pathogens 4. Immune Response: specific response to a infection that has spread through body triggered by the presence of antigens/pathogens Slide # 7

8 The Immune Response: The Third and Final Line of Defense 1. Macrophages ingest pathogen; send out chemical signal to call Helper T cells to the site of infection 2. By the time Helper T cells arrive, macrophages have incorporated pathogen’s antigens onto its own cell membrane 3. Helper T cell attaches to antigens on macrophage & develops new binding site that recognizes foreign antigens (copies enemy’s information) 4. Helper T cell passes information to two different attack cells: B cells & Killer T cells Slide # 8

9 Macrophage T Cell Helper T Cell Killer T Cell Infected Cell Antigens are displayed on surface of macrophage T cell binds to activated macrophage T cell, activated by macrophage, becomes a helper T cell Helper T cell activates killer T cells and B cells Killer T cells bind to infected cells, disrupting their cell membranes and destroying them Immune Response Slide # 9

10 Killer T Cells: Have Direct Contact with Antigens 1. Killer T cells come into direct contact w/ a cell; pierces hole in cell wall a. Water moves into the cell & the cell swells & bursts open 2. Killer T cells produced at same time as B cells 3. Killer T cells destroy protists, virus infected cells, & cancer cells Slide # 10

11 B Cells Produce Antibodies 1.B cells release antibodies 2.Millions of B cells are cloned & millions of antibodies are released into blood when fighting infection 3.Antibody: Y shaped protein that “tags” an antigen for destruction 4. Antibodies also bind to virus & bacterial toxins & neutralizes them Antigen Antibody Antigen Antibody Antigen- binding sites Slide # 11

12 Active vs. Passive Immunity 1.Passive Immunity is acquired when antibodies to the antigen are injected into the body. They do not last. (Ex. Breast milk) 2.Active immunity is produced when the body creates its own antibodies after being exposed to an antigen. –Acquired through vaccinations –Acquired through infection of pathogen. –Antibodies are constantly produced by memory cells created when the body was first infected. Slide # 12

13 Interval between exposures First exposure Second exposure Time Antibody Concentration Why you don’t get chicken pox twice.

14 Immune System Disorders/Problems 1.An allergy is a disorder in which the immune system overreacts to the presence of an antigen such as pollen. 2.An autoimmune disease is one in which the immune system attacks its own body cells. Ex. M.S. and Arthritis 3.Rejection of organ transplants (cells are foreign). 4.Cancer cells are naturally destroyed by the body; however, when the body fails to recognize them they spread causing tumors. Slide # 14

15 Cells of the Immune System The body's innate defense against disease is natural immunity. The immune system consists of white blood cells, cell products, and other substances.

16 Cells of the Immune System 1. Lymphocytes include: a. T cells (T for thymus, where they mature) b. B cells (B for bone marrow, where they originate) c. Natural killer (NK) cells (less abundant) 2. Macrophages & Granulocytes: Phagocytic or "cell-eating” a. Neutrophils -- form an early line of defense against bacterial infections (Non-specific response) & involved in inflammatory response b. Eosinophils -- Their natural role is to defend us against parasites ; also release chemicals that damage lungs and contribute to asthma c. Basophils -- involved in inflammatory response & allergic reactions d. Mast cells settle in connective tissues and usually do not circulate in the blood stream. Release histamine; contributes to allergic reactions Mast cell with Salmonella bacteria


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