Immune system

    Cards (42)

    • 1.      Phagocyte recognises (foreign) antigen;
      2.      (Pathogen)engulfed
      3.      Enclosed in vacuole
      4.      (Vacuole) fuses with lysosome;
      5.      Lysosome contains enzymes;
      6.      Pathogen digested
    • Physical barriers to infection include: • Skin which is a tough physical barrier consisting of keratin.Stomach acid (hydrochloric acid) which kills bacteria. • Gut and skin floranatural bacterial flora competes with pathogens for food and space
    • Antibodies In the humoral response plasma cells produce antibodies. These are made of four polypeptides chains forming a Y shaped structure. These are complementary to only a single antigen. They work by forming an antigen-antibody complex which serve as markers for phagocytes to destroy attached cells. Due to antibodies having two binding sites they can also clump cells together making them easier for phagocytes to find. This process is called agglutination.
    • Non Specific Immune Response
      Non-specific responses of the body to infection
    • Ethical Considerations There are a number of ethical consideration to take into account when looking at vaccines, these include:
      • Production and testing of vaccines may be done on animals
      • The risks of the vaccine need to be balanced with the benefits
      • The vaccine must be tested on humans first to determine toxicity
      • Vaccinations are very expensive
      • Should vaccinations be compulsory or should people be able to opt out of having a vaccination?
    • Specific Immune Response
      Antigen specific and produces responses specific to one type of pathogen only
    • Types of immunity
      • Active
      • Passive
    • Monoclonal Antibodies

      Clones of a single type of antibody produced due to the many different types of antigens
    • Vaccines
      A way of introducing a pathogen into the body in order to produce an immune response
    • Inflammation
      1. Histamines released by damaged white tissues
      2. Vasodilation increases blood flow to infected area
      3. Increases permeability of blood vessels
      4. Antibodies, white blood cells and plasma leak out into infected tissue
      5. Destroy pathogen
    • Lymphocytes
      • B cells mature in the bone marrow and are involved in the humoral response
      • T cells move from the bone marrow to the thymus gland where they mature, and are involved in cell mediated response
    • Active immunity
      Results from the production of antibodies by the immune system in response to the presence of an antigen
    • Monoclonal Antibodies

      • Medically useful to produce many clones of a single type of antibody
      • Have many different uses
    • Specific immune response glossary
      • Memory cells
      • B effector or plasma cells
      • T helper cells
      • T killer cells
    • Vaccines
      • The pathogen may be dead or inactivated, but the antigens on its surface will still produce an immune response
      • This is an example of active immunity and results in the creation of memory B cells which will be able trigger a rapid secondary immune response should the same pathogen ever be detected again
    • HIV
      Human immunodeficiency virus, a pathogen that can lead to the disease acquired immune deficiency syndrome (AIDS)
    • Antibiotics are ineffective against HIV and viruses. This is because many antibiotics work by preventing bacteria from making cells walls. Without this the bacterial cell cannot control the entry and exit of water and will therefore burst. However since viruses don’t have a cell wall and are reproduced within a host cell they are unaffected by antibiotics. Instead HIV is treated with antiretroviral drugs which keep the levels of HIV in the blood stream very low, reducing the impact on the hosts immune system.
    • Lysozyme action
      Enzymes found in secretions such as tears and mucus which kill bacterial cells by damaging their cell wall
    • Passive immunity
      Results from the introduction of antibodies from another person or animal
    • Uses of Monoclonal Antibodies
      • Direct Therapy - Target and destroy cancerous cells
      • Indirect Therapy - Attach drugs to target specific cells
      • Diagnosis - Measure levels of particular antigens
      • Pregnancy testing - Detect human chorionic gonadotrophin
    • Factors that determine the success of a vaccination program
      • Cost of the vaccine
      • Severity of the side effects
      • Ease of production, transportation and administration
      • Number of people who need to be vaccinated for herd immunity
    • Memory cells
      Cells which replicate themselves when exposed to an invading pathogen and remain in the lymph nodes for decades searching for the same antigen, resulting in a much faster immune response should the individual be infected by the same pathogen again
    • HIV structure
      • Lipid envelope with embedded attachment proteins
      • Protein capsid containing genetic material (RNA) and reverse transcriptase enzymes
    • Direct Therapy

      Monoclonal antibodies specific to antigens on cancerous cells are used to target and destroy the cells
    • Interferon
      Prevents viruses spreading to uninfected cells by stopping protein synthesis in viruses
    • Subtypes of immunity
      • Natural
      • Artificial
    • Herd immunity
      If you vaccinate enough people in the population then eventually the pathogen won't be able to be transmitted from different hosts, therefore protecting those who aren't vaccinated
    • HIV replication
      1. Binds to CD4 protein on T-Helper cells
      2. Capsid fuses with cell surface membrane
      3. RNA and reverse transcriptase enter cell
      4. Reverse transcriptase converts RNA to DNA
      5. DNA moves into cell nucleus
      6. Cell begins producing viral HIV components
    • Phagocytosis
      1. White blood cells engulf pathogens
      2. Fuse to pathogen
      3. Enclose in phagocytic vacuole with lysosome
      4. Pathogen is engulfed and destroyed
      5. Chemical markers (antigens) presented on surface of phagocyte
      6. Phagocyte becomes antigen presenting cell
      7. Activates immune response if antigen is recognised as foreign
    • Indirect Therapy
      Drugs can be attached to monoclonal antibodies to direct the drug towards cells displaying a particular antigen
    • B effector or plasma cells
      Antibody producing cells
    • Natural active immunity

      Arises from being exposed to an antigen/getting the disease
    • Vaccines are not always useful in preventing a disease outbreak because the antigen on the surface of the pathogen can change, therefore removing immunity
    • T helper cells
      Stimulate B cells and T killer cells to divide
    • Natural passive immunity
      Result of crossing of mother's antibodies through the placenta and their presence in breast milk
    • Diagnosis
      Particular antigens are targeted by antibodies to measure levels of that antigen in the body
    • The reverse transcriptase enzyme catalyses the production of DNA from the RNA
    • Immunity against Influenza virus is only short lived
    • T killer cells
      Destroy pathogen infected cells
    • Pregnancy testing
      Monoclonal antibodies in home pregnancy kits are specific to the hormone human chorionic gonadotrophin
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