diseases and immunity

disease-causing organism

organism that is infected by a pathogen

• Bacteria • Fungi • Protoctists

a disease caused by a pathogen that can be transmitted from one host to another diseases can be transmitted either; - directly: contact through body fluids such as blood - indirectly: through air, water, food, contaminated surfaces or animals

block pathogens from entering the body include: - Skin - Hairs in the nose

• substances that trap or kill pathogens include: • Mucus produces pra mucous membranes. They are sticky, therefore they trap bacteria and other pathogens • Stomach acid. Highly acidic therefore kills pathogens

phagocytes lymphocytes

surround and engulf a pathogen (phagocytosis) then destroy it

produce antibodies, proteins which attach to pathogens and so mark them for destruction

• A clean water supply • Good personal hygiene • Hygienic food preparation • Proper waste disposal • Treatment of sewage

production of antibodies by the immune system in response to antigens - gained after infection of that pathogen

temporary immunity - gained when antibodies are transferred to the body from another individual (for example milk during breast-feeding)

• mark the antigen for phagocytosis and destruction by phagocytes or • cause the pathogen to break open and die

when the immune system responds to a specific pathogen for the first time

immune system after re-infection of the same pathogen. Involves memory cells

remain in the blood after the pathogens in an infection have been destroyed. They ‘remember’ specific pathogens, so that if the organism is infected again, the immune system may produce antibodies quicker.

small amounts or dead or weakened pathogens that cannot cause disease