2Germ TheoryGerm theory proposes that microorganisms cause diseases (not spirits, as once believed).Proposed by Louis PasteurLed to rapid advances in understanding diseaseSupported by Koch’s postulates.Disease-causing agents, or particles, are called pathogens.
3There are different types of pathogens Bacteria are single-celled organisms:Cause illness by destroying cells, release toxic chemicalsEx: Food poisoning, MRSAViruses are genetic material surrounded by a protein coat:Force host cells to make more viruses, smallEx: Flu, Cold, HIVFungi can be multicellular or single-celled:Take nutrients from host cells by piercing healthy cellsOccur in warm and damp placesEx: Athlete’s footProtozoa are single-celled organisms.Use host cells to complete their life cyclesTake nutrients from host cellEx: MalariaReview: Parasite
4Different pathogens cause common infectious diseases
5Pathogens 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 surfaceBreathing in infected airVectors :Carry a pathogen and transmit into healthy cellsEx: Insects (ticks, mosquitoes, fleas), food
6Direct contact requires touching an infected individual. Includes:KissingSexual intercourseHand shakingtick
7Many 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.
8Cells 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.
12Immunity 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 milkGeneticsActive immunity occurs after a specific immune response.Having chicken poxAcquired Immunity occurs after given a vaccine.Flu shot
13Artificial methods are used to control pathogens Antibiotics and antiseptics cause pathogens to burstAntiseptics kill pathogens outside of the bodyDo not target specific pathogensEx: Vinegar, Soap, Rubbing Alcohol, PurelAntibiotics kill pathogens inside the body.Target one specific bacterium or fungusNOT effective against viruses
14Antibiotic Resistance 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.A bacterium carries genes for antibiotic resistance on a plasmid.A copy of the plasmid is transferred through conjugation.Resistance is quickly spread through many bacteria.
15Vaccines artificially produce acquired immunity Vaccines control pathogens and diseaseInjected 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.
16How a vaccination provides immunity Antigens in a vaccine trigger an immune response, and memory B cells are made.1memory B cellsStimulates a specific immune responseCauses memory cells to be producedA memory B cell is stimulated when the real pathogen binds to it.2Allows immune system to respond quickly to infectionThe B cell quickly activates and makes antibodies that fight the pathogens before you get sick.3Has a fast response, a person will not get sick