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IMMUNE SYSTEM

IMMUNE SYSTEM. Biology 2201. The ability of the body to fight infection by producing antibodies or cells that deactivate foreign substances. Immune System.

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IMMUNE SYSTEM

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  1. IMMUNE SYSTEM Biology 2201

  2. The ability of the body to fight infection by producing antibodies or cells that deactivate foreign substances.

  3. Immune System • The system in the body responsible for maintaining homeostasis by recognizing harmful from no harmful organisms and produces an appropriate response

  4. Pathogen: virus, bacteria or other microorganism that causes disease • Antigen: Toxin produced by a foreign invader • Antibody • Y shaped protein molecule created by plasma cells during specific immune response. • Function is to attach to and deactivate antigens/pathogens present in the bloodstream during a specific immune response

  5. Parts of the Immune System • Blood( white blood cells in particular) • Lymph nodes • Spleen • Bone marrow(to produce more WBC’s

  6. There are 2 types of diseases: • Noninfectious - often called functional diseases, whereby an organ does not work properly anymore. (e.g. cancer, heart disease) • Infectious - caused by a disease-producing organism called a pathogen. (e.g. measles, colds, flu, malaria, etc.)

  7. The body’s defenses against pathogens include: 1. Non-specific Defenses 2. Specific Defenses

  8. Body’s Lines of Defense • First Line • Second Line –non specific Immune response • Third Line- specific immune response

  9. 1. Non-specific Defenses • These are your first line of defense against pathogens. They guard against all foreign organisms and not just any one specific organism. • The major forms of non-specific defenses come into action as follows:

  10. (A) Physical and Chemical Barriers • skin • membrane linings • sweat • saliva • stomach acid • urine • tears • mucus

  11. (B) Inflammatory Response – 2nd line Defenses • It is a reaction that causes redness, swelling, pain, and warmth in the area of infection. Cells damaged by the infection release chemicals, that causes an increase in blood flow to the infected area. • These are defenses that the body uses no matter what the invader may be. These defenses are: • A. Phagocytosis- done by macrophages • B. Natural Killers cells- the killer cells kill infected cells • Inflammation- cuts off the infected area from the rest of the body • Fever-raising temperature kills invading microorganisms • This results in WBCs called phagocytes being transported to the site of the infection. The phagocytes ingest the pathogens and damaged tissue, resulting in the formation of puss. This usually kills the pathogen. Sometimes the infection gets to the lymphatic system and causes the lymph nodes to swell.

  12. If the infection is serious, it results in the formation of more phagocytes. If this does not finish the infection, chemicals are released that increase the body temperature. This is called a fever. A fever serves two major purposes: (i) it kills microorganisms that cannot survive the higher temperature (ii) it slows down microorganisms, giving the WBCs a chance to destroy them

  13. * If the pathogen is a virus, another defense system occurs. It is called interferon. It is a substance produced by cells infected by a virus. It causes non-infected cells to produce an enzyme that blocks reproduction of the virus.

  14. 2. Specific Defenses – 3rd line Defenses • If the pathogen gets past the non-specific defenses, it will encounter the specific defenses. It is at this stage that the immune system comes into play. • These are defenses that the body uses for specific invaders. These defenses include • The production of antibodies • The killing of specifically infected body cells and microbes • It provides the body with the ability to fight infection through the production of antibodies or cells that inactivate foreign substances or cells.

  15. The immune system includes all parts of the body that are involved in the recognition and destruction of foreign materials. • The basis of immunity lies in the body’s ability to distinguish between its own substances (itself) and foreign substances (non-self). • Any foreign substance that triggers a specific defense response is called an antigen.

  16. Antigens are usually protein, but can be carbohydrates, lipids or nucleic acids. These are carried on the surface of bacteria, viruses, and other pathogens that may enter the body. • The response to an antigen is called an immune response.

  17. The Mechanism of specific Immune response • When you become infected with a pathogen the following series of events occurs. • Step 1: The pathogen is attacked by macrophages and they engulf the organism /particle • Step 2: the macrophage displays a form of the antigen on its surface • Step 3: helper T cells recognize the antigen on the surface of the macrophage and it begins two forms of response. One is called cellular immunity and the other is Humoral or blood Immunity • Note: suppressor T cells release substances that slow down the immune response and eventually stop it.

  18. Cellular And Humoral or Blood immunity • Cellular Immunity • Helper T- cells activates a Cytotoxic T- cell • Cytotoxic T- cell divides T- cells into Cytotoxic T- cells and memory T-cells • Killer T- cells kill infected cells • Memory T-cells remain ready for a second invasion • Humoral or Blood immunity • Helper T -cell activates a B- cell • B- cell divides into plasma and memory B- cells • Plasma cells create antibodies • Antibodies attach to and deactivate pathogens found in blood • Memory B -cells remain ready for a second invasion

  19. Types of Immunity

  20. 1. Active Immunity • The body produces its own antibodies or killer T cells to attack a specific antigen. • Ex. You have a throat infection and you have built up antibodies against a clod virus • You were given a vaccination for polio so your body built up antibodies to the polio antigen • Active immunity is long lasting. It develops in two ways: • (i) when a person had the disease • (ii) by vaccination of a weakened or milder form of the pathogen • Vaccination: an injection of a weakened strain of an infectious microbe that causes the body to produce antibodies without harming the body

  21. 2. Passive Immunity • This is borrowed immunity. The person is given antibodies from another person or animal who has been infected by the antigen. • Ex. Maternal immunity: a mother gives antibodies to her child while breast feeding. This protects the baby against infection until the baby is ale to produce its own antibodies • It is only temporary - lasting only 30 days, but faster acting then the active immunity response.

  22. Immune System and Transplants • The immune response can result in problems with organ transplants. The body recognizes transplanted organs as foreign to the body, and tries to fight them as if they were a pathogen. • The result would be the destruction of the transplanted organ. This is controlled in two ways:

  23. (i) Donor and recipient are closely matched. (ii) Recipient is given drugs to suppress the immune system.

  24. An immune response can involve two categories of reactions: • B cell reactions • T cell reactions

  25. 1. Antigen enters body 2. Macrophage ingests antigen and displays form of antigen on cell membrane 3. T cell recognizes antigen 3. B cell recognizes antigen 4. Helper T cell recognizes antigen displayed by macrophage 5. T cell stimulated to divide by helper T cell to form killer T cells and memory T cells 5. B cell stimulated to divide by helper T cell to form plasma cells and memory B cells 6. Killer T cells bind to virus-infected cells 6. Plasma cells produce antibodies that bind to antigen 7. If antigen enters body again, memory T cells divide to produce new killer T cells 7. If antigen enters body again, memory B cells divide to produce new plasma cells

  26. Types of Immunity Responses

  27. 1. Primary Immune Response • This occurs when an antigen enters the body for the first time. • It takes 5 days for the body to recognize the antigen and start production of antibodies. • It takes another 10 to 15 days for the antibodies to build up.

  28. 2. Secondary Immune Response • This occurs if an antigen that has entered the body before, enters a second time. • There is a shorter response time of only 1 to 2 days for antibody production. • Memory B cells – easily recognize the antigens and produce mass quantities of antibodies in a very short period of time • Memory T- cells- quickly recognize infected cells and kill them quickly

  29. Autoimmune Diseases • Autoimmune diseases are disease where the immune system begins to attack itself. • ex/; Rheumatoid Arthritis- crippling disease of the joints • Lupus-disease of blood and organs • Multiple sclerosis-disease of the nervous system Causes” unknown Cures/ Treatments no cures. Usually treated with drugs

  30. Allergies and Allergic reaction • Allergy- an exaggerated response by the immune system to an allergen • Allergen: a normally harmless substance that causes an allergic reaction. Ex. Dust pollen mould food insect stings • Types of allergic reactions there are twp types of allergic reactions • Immediate-occurs within seconds and abnormally lasts for about 30 mins • Delayed-takes longer to react and can last for a much longer time

  31. Mechanism of an allergic Reaction • During an allergic reaction antibodies cause histamines to be released from certain cells • Histamines • Chemical released into the blood stream that cause • Swelling inflammation of tissues • Release of fluids(runny nose and eyes • Muscle spasms(some cases • Anaphylaxis or anaphylactic shock: • This is the sudden and severe allergic reaction to a substance that can cause death

  32. Treatments for allergies • Avoidance of material-especially food • Epinephrine-epi pen • Contains a hormone called epinephrine that helps restore normal blood pressure during anaphylactic shock • Antihistamines • Drugs such as Benadryl , Sudafed and Actified contain chemical called antihistamines that help reduce the amount of histamine in the blood. This reduces the allergic reaction

  33. AIDS

  34. Acquired Immune Deficiency Syndrome • The cause of AIDS is a virus called the human immunodeficiency virus - HIV. • The virus attacks the helper T cells of the immune system. • The virus enters the T cell and remains within the cells for months or even years without producing symptoms.

  35. The virus has a number of disturbing properties: • (1) It is able to mutate giving it the ability to produce different strains. (HIV-1;1981, HIV-2; 1985) • (2) It causes change in the cell membrane of the T cell causing them to fuse together. This allows the virus to pass from cell to cell without entering the bloodstream and becoming exposed to antibodies present in the blood.

  36. When HIV becomes active, the individual develops AIDS. The virus reproduces, spreads, and destroys helper T cells. The T cells become a HIV factory. • Some possible triggers for HIV activation are: (i) other co-infections (ii) contain a gene like a ticking time bomb

  37. The decrease in helper T cells weakens the immune system. The body loses its ability to fight disease and becomes susceptible to opportunistic infections and malignancies.

  38. Spread of AIDS • 1. Sexually transmitted • 2. Blood-to-blood contact • 3. Mother to fetus during pregnancy or at the time of birth • * In rare cases through breast milk

  39. Prevention of AIDS • 1. Abstinence from sexual activity • 2. Use of a latex condom, plus spermicidal nonoxynol-9 • 3. Avoid sharing of needles during of intravenous drug use

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