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T he Immune System

T he Immune System. Germ T heory. Germ theory proposes that microorganisms cause diseases (not spirits, as once believed). P roposed by Louis Pasteur L ed to rapid advances in understanding disease. Supported by Koch’s postulates .

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T he Immune System

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  1. The Immune System

  2. 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.

  3. 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 • Protozoaare single-celled organisms. • Use host cells to complete their life cycles • Take nutrients from host cell • Ex: Malaria • Review: Parasite

  4. Different pathogens cause common infectious diseases

  5. Pathogens can enter the body in different ways • Pathogens can be transferred by indirect or direct contact. • Indirect contactdoes 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 (ticks, mosquitoes, fleas), food

  6. Direct contactrequires touching an infected individual. • Includes: • Kissing • Sexual intercourse • Hand shaking tick

  7. 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. • Skin is the (first) physical barrier to infection. • Mucous membranes trap pathogens entering the body. • The circulatory system transports immune cells.

  8. 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.

  9. antibody pathogens • Complement proteins weaken pathogen membranes. • Antibodies make pathogens ineffective. 3 types of proteins fight off invading pathogens • Interferons prevent viruses from infecting healthy cells.

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  11. 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 withoutan immune response. • Mother’s milk • Genetics • Active immunity occurs after aspecific immune response. • Having chicken pox • Acquired Immunity occurs after given a vaccine. • Flu shot

  12. Artificial methods are used to control pathogens Antibiotics and antiseptics cause pathogens to burst • Antibiotics kill pathogens inside the body. • Target one specific bacterium or fungus • NOT effective against viruses • Antiseptics kill pathogens outside of the body • Do not target specific pathogens • Ex: Vinegar, Soap, Rubbing Alcohol, Purel

  13. A bacterium carriesgenes for antibioticresistance on a plasmid. A copy of the plasmid is transferredthrough conjugation. Resistance is quicklyspread throughmany bacteria. • Overuse and misuse of antibiotics can cause medicines to become ineffective. • Some bacteria in a population have genes that make them immune to antibiotics. • These bacteria spread the gene, making the antibiotics useless. Antibiotic Resistance

  14. Vaccines artificially produce acquired immunity • 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.

  15. 1 Antigens in a vaccinetrigger an immune response, and memory B cells are made. memory B cells A memory B cell isstimulated when the real pathogen binds to it. 2 The B cell quickly activates and makes antibodies that fight the pathogens before you get sick. 3 How a vaccination provides immunity • Stimulates a specific immune response • Causes memory cells to be produced • Allows immune system to respond quickly to infection • Has a fast response, a person will not get sick

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