Immunity

Immunity

Immune system
1. Primary defences
  1. The skin is a physical barrier, blocking pathogens from entering the body. As a chemical barrier by producing chemicals that are antimicrobal and can lower pH.
  2. Mucous membranes protect body openings, traps pathogens and contains antimicrobal enzymes
2. Immune response is the body's reaction to a foreign antigen
  1. 1. Phagocytes engulf pathogens. Recognises the antigens on a pathogen. The cytoplasm moves around the pathogen, engulfing it. The pathogen is inside a phagocytic vacuole. A lysosome fuses with the vacuole and breaks down the pahtogen. The phagocyte sticks the antigen on its surface to activate other immune cells
  2. 2. Phagocytes activate T lymphocytes. The receptors on the surface bind to the antigen on the phagocytes. Each T lymphocyte has a different receptor. This activates other T lymphocytes and divides and differenciates. Some activate B lymphocytes and some become memory cells
  3. 3. T lymphocytes active B lymphocyte which divide into plasma cells. B lymphocytes are covered in antibodies (they are specific). They bind to antigens. The B lymphocytes divide into plasma cells and memory cells.
  4. 4 Plasma cells make more antibodies to a specific antigen.
3. Primary vs Secondary response
  1. Primary response is slow. Its when a pathogen enters your body for the first time. It is slow because there are not as many B lymphocytes. Eventually the body will produce enough, meanwhile the person will have symptoms. The B and T lymphocytes produce memory cells.
    1. Secondary response is faster. Memory B cells produce the right plasma cells and T cell divide into the correct T cells. There are no symptoms
4. Antigen-Antibody complex: Variable region form the antibody binding region. Complementary to the antigen. Hinge region allow flexibility. Constant regions allow binding to receptors on immune system cells. Disulphide bridges hold the polypeptide chain together.
  1. Agglutinating pathogens: Binding to many pathogen at once. Neutralising toxins: Antibodies bind to the toxins produced by the pathogens. Preventing binding: Antibodies may block the antigens from binding to the receptors on the host cells
Vaccinations
1. Active and passive
  1. Active: Natural -Immune after catching disease. Artificial - Become immune after vaccination of small dose of antigens
    1. Exposure to antigen, protection take long to develop, protection is long term, memory cell produced
  2. Passive: Natural - Baby become immune by receiving antibodies from breastmilk. Artificial -Being injected antibodies from somewhere else
    1. No exposure to antigen, protection is immediate, protection is short term, memory cells not produced
2. Control disease
  1. Vaccination help avoid symptoms like in primary response. Vaccines contain antigens that cause your body to produce memory cells. Many people getting vaccines (herd immunity)
3. New influenza vaccination
  1. The antigens on the surface change so the vaccination is chose every year to suit which it will benefit more so. WHO and CDC
4. Sources of medicine
  1. Natural compounds, only small proportion have been investigated, Need to protect biodiversity
  2. Discovered? By accident, observation of wildlife, traditional medicines.

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	Created by Nikita96 over 11 years ago