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Published byShawn Golden Modified over 9 years ago
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Germ Theory Germ theory proposes that microorganisms cause diseases (not spirits, as once believed). – Proposed by Louis Pasteur – Led to rapid advances in understanding disease Supported by Koch’s postulates. –Disease-causing agents, or particles, are called pathogens.
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There are different types of pathogens Bacteria are single-celled organisms: – Cause illness by destroying cells, release toxic chemicals – Ex: Food poisoning, MRSA Viruses are genetic material surrounded by a protein coat: –Force host cells to make more viruses, small –Ex: Flu, Cold, HIV Fungi can be multicellular or single-celled: –Take nutrients from host cells by piercing healthy cells –Occur in warm and damp places –Ex: Athlete’s foot Protozoa are single-celled organisms. –use host cells to complete their life cycles –take nutrients from host cell –Ex: Malaria Review: Parasite
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Different pathogens cause common infectious diseases
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Pathogens can enter the body in different ways Pathogens can be transferred by indirect or direct contact. Indirect contact does not require touching an infected individual. – Touching an infected surface – Breathing in infected air Vectors :Carry a pathogen and transmit into healthy cells – Ex: Insects, Food
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Direct contact requires touching an infected individual. – Includes: Kissing Sexual intercourse Hand shaking tick
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Many body systems protect you from pathogens The immune system is the body system that fights off infection and pathogens. Many other tissues and systems help the immune system. first – Skin is the (first) physical barrier to infection. – Mucous membranes trap pathogens entering the body. – The circulatory system transports immune cells.
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Cells and proteins fight the body’s infections White blood cells attack infections inside the body. – Phagocytes engulf and destroy pathogens. – T cells destroy infected cells. – B cells produce antibodies, which deactivate the pathogen.
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antibody pathogens 3 types of proteins fight off invading pathogens –Complement proteins weaken pathogen membranes. –Antibodies make pathogens ineffective. –Interferons prevent viruses from infecting healthy cells.
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Immunity prevents a person from getting sick from a pathogen In all types of immunity, pathogens are destroyed before you get sick. – Passive immunity occurs without an immune response. Mother’s milk Genetics – Active immunity occurs after a specific immune response. Having chicken pox – Acquired Immunity occurs after given a vaccine. Flu shot
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Antibiotics and antiseptics cause pathogens to burst Antiseptics kill pathogens outside of the body –Do not target specific pathogens –Ex: Vinegar, Soap, Rubbing Alcohol, Purel Antibiotics kill pathogens inside the body. –Target one specific bacterium or fungus –NOT effective against viruses
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Vaccines control pathogens and disease – Injected with antibodies that have been exposed to the pathogen. Gives instant but short- term protection. – Given mild or dead version of the pathogen. Your body makes the antigens itself for long-term protection. Memory B cells stay for a long time, ready for another attack from the same organism. Vaccines artificially produce acquired immunity
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