Topic 11: Human Health and Physiology 11.1 Defense Against Infectious Diseases

Describe the process of blood clotting Outline the principle of challenge and response, clonal selection and memory cells as the basis of immunity Define active and passive immunity Explain antibody production Describe the production of monoclonal antibodies and their use in diagnosis and treatment Explain the principles of vaccination Discuss the benefits and dangers of vaccinations

Describe the process of blood clotting When human tissues and organs are injured, so are blood vessels The body reacts in a non-specific response called clotting Non-specific – the body does not produce substances for a specific pathogen or disease (for example - antibodies) Equally important, it does not clot when there isn’t an injury which would prevent blood flow

Describe the process of blood clotting The process: Blood reacts with: the air damaged cells platelets Step 1: Damaged cells and platelets release an enzyme called thrombokinase Step 2: The combination thrombokinase, and clotting factors (X and VII) and Ca2+ ions will change prothrombin (inactive form) into thrombin.

Describe the process of blood clotting Step 3: Thrombin will change soluble fibrinogen into smaller insoluble fibrin molecules. This forms a net that catches platelets and erythrocytes (RBC) and forms a plug or clot.

Outline the principle of challenge and response, clonal selection and memory cells as the basis of immunity Explain antibody production Blood contains red blood cells (erythrocytes) and white blood cells (leukocytes). It is the leukocytes that play a major role in the immune system There are many different types of leukocytes

Outline the principle of challenge and response, clonal selection and memory cells as the basis of immunity Explain antibody production Immunity – the body’s ability to recognize self and distinguish self from non-self substances (any non-self substance is called an antigen) Antibody – a special type of protein constructed in the shape of a “Y” The top part of the “Y” is the antigen binding site This binding site is what gives the antibody its specificity

Outline the principle of challenge and response, clonal selection and memory cells as the basis of immunity Explain antibody production Challenge and response” – when a pathogen invades an organism, the organism is challenged and must respond

Outline the principle of challenge and response, clonal selection and memory cells as the basis of immunity Explain antibody production Step 1: The macrophages ingests the pathogen (phagocytosis) Step 2: Part of the bacterial cell wall and cell membrane is displayed on the outside of the macrophage (on MHC protein)

Outline the principle of challenge and response, clonal selection and memory cells as the basis of immunity Explain antibody production Step 3: The macrophage travels to the lymph node The lymph node contains cells called lymphocytes When the macrophage is in the lymph node it will select a helper T- cell which has receptors that are complimentary to the antigen that the macrophage is carrying Step 4: The T-cell is activated and will divide by mitosis creating a clone The cloned T-cells will activate B-cells which also have surface receptors that are complementary to the antigen. This is called clonal selection (the process when the macrophage selects which T-cells and B-cells have required surface receptors)

Outline the principle of challenge and response, clonal selection and memory cells as the basis of immunity Explain antibody production Step 5: B-cells also form clones. B-cells produce memory cells that create a faster and stronger response to an antigen that has infected the body before B-cells also become plasma cells which will make large amounts of antibodies This is called clonal expansion Clonal expansion – is the process in which T-cell and B- cells form clones through mitosis. This results in a large number of cells to deal with the infection.

Outline the principle of challenge and response, clonal selection and memory cells as the basis of immunity Explain antibody production

Define active and passive immunity Active immunity – production of antibodies by the organism itself after the body's defense mechanisms have been stimulated by antigens. This can be from a previous infection or injection of antigens. Passive immunity – the immunity that is due to the acquisition of antibodies from another organism in which active immunity has been stimulated (placenta, colostrum, injection of antibodies)

Describe the production of monoclonal antibodies and their use in diagnosis and treatment Monoclonal antibodies can be used to determine someone's blood type or vaccinate a patient. They are obtained from a single B-cell clone that is fused with an immortal tumor cell.

Describe the production of monoclonal antibodies and their use in diagnosis and treatment Example: Using Monoclonal Antibodies to Determine Blood Type A mouse is injected with an antigen (for example, human red blood cell type A) Mouse plasma cells will produce antibodies in response to the human red blood cells The plasma cells are extracted and fused with B-cell tumor cells. These hybrid cells are grown in culture and will produce identical antibodies (anti-A) Now, if you add human blood to the antibodies produced by the hybrid cells. If you see clotting than you know that the blood sample contains type A blood.

Explain the principles of vaccination Vaccination uses the same principles as memory cells in creating a fast secondary response to an antigen. Vaccination is the deliberate exposure of a patient to the antigens (epitopes) of a dead or a weakened pathogen. The patient develops memory cells against the antigen. Recovery is therefore rapid perhaps showing little or any sign of infection with these serious diseases because: high antibody levels rapid response Used for serious disease (polio, tetanus, measles, etc...)

Discuss the benefits and dangers of vaccinations Keyword

Discuss the benefits and dangers of vaccinations