B10 Diseases and Immunity

a disease causing organism

a disease in which the pathogens can be passed from one host to another

(a) by direct contact, including through blood and other body fluids (b) indirectly, including from contaminated surfaces, food, animals and air

Virus structure is simply genetic material inside a protein coat

Acts as a mechanical barrier, covering almost all parts of your body and preventing pathogens from entering. If cut, it heals quickly, often forming a scab.

Trap and block pathogens from being inhaled further into the respiratory system.

Mucus is produced in the respiratory tract and traps pathogens. Cilia beat to move mucus up to the throat where it is swallowed and destroyed by stomach acid.

Contains hydrochloric acid, which is strong enough to kill pathogens that have been swallowed in mucus or with food and water.

Defend the body by either engulfing and digesting pathogens (phagocytosis) or by producing antibodies that clump pathogens together, making them easier to destroy.

Safe drinking water ensures water is free of pathogens which will prevent waterborne diseases e.g. cholera.

Washing hands with soap, correct food cooking methods and hygienic preparation of food will help to prevent contamination of food with harmful bacteria and fungi

Washing with soap or using tissues to catch sneezes and coughs and then disposing of them will reduce transmission of diseases such as colds and flu.

Proper disposal of waste, such as food waste, reduces pests like flies, which can act as vectors and spread transmissible diseases

Treatment of sewage removes harmful pathogens from waste before it is released into the environment. This reduces the risk of diseases spreading in contaminated water.

defence against a pathogen by antibody production in the body

-Antigens on the pathogen stimulates lymphocytes to produce antibodies -Antibodies bind to the antigens and help destroy the pathogen -Antibodies also mark pathogens for destruction by phagocytes -Memory cells are produced and remain in the body -This gives long-term active immunity

-Weakened or dead pathogens, or their antigens, are introduced into the body by vaccination -The antigens stimulate an immune response -Lymphocytes produce antibodies -Memory cells are produced, giving long-term active immunity -If the same pathogen enters again, antibodies are produced quickly and destroy the pathogen before it causes disease

proteins that bind to antigens leading to direct destruction of pathogens or marking of pathogens for destruction by phagocytes

(a) weakened pathogens or their antigens are put into the body (b) the antigens stimulate an immune response by lymphocytes which produce antibodies (c) memory cells are produced that give long-term immunity

Vaccinations are available for some pathogens to help control the spread of diseases

-The antigen on the flu virus changes shape -New antibodies are needed to match the new antigen