2 The Nature of Disease Pathogens Disease producing agents, such as, bacteria, viruses, protozoans, fungi & other parasitesInfectious diseaseAny disease caused by the presence of pathogens in the body
3 The Nature of DiseaseKoch’s postulates of (a procedure to establish the cause of a disease)1) A pathogen must be found in the body of a sick organism2) The pathogen must be isolated & grown in the lab to produce a culture3) When the cultured pathogen is placed in a new host, it should cause the same disease4) The pathogen should be isolated from the new host and shown to be the original pathogen
4 The Nature of Disease Endemic disease Disease that are constantly present in a population (ex: common cold)EpidemicWhen many people in a given area are affected with the same disease at about the same time (ex: influenza)
5 The Nature of Disease Antibiotics Substances produced by microorganisms that, in small amounts, will kill or inhibit the growth & reproduction of other microorganismsEx: Penicillin, an antibiotic produced by a fungus, has been in use for over years; many microorganisms are now resistant to penicillin
6 The Immune System Innate Immunity Your body’s own built-in defense systemFirst (& best) line of defense:Unbroken skinBody secretions, such as mucus, tears, sweat, & saliva
7 The Immune SystemSecond line of defense is inflammatory response:Fever= increased body temperature slows or stops the growth of pathogensPhagocytes = white blood cells, such as macrophages, that destroy pathogensInterferon = proteins that protect cells from viruses
9 The Immune SystemThird line of defense is cellular immunity:Lymphocytes are types of white blood cells that defend the body against foreign substancesT cells are lymphocytes that defend against abnormal cells & pathogens inside livings cellsB cells are lymphocytes that provide immunity against antigens & pathogens in the body fluids
11 The Immune System Lymph Tissue fluid (to bathe, nourish cells) after it enters the lymph vessels that will return it to the bloodLymph nodesGlands that filter pathogens from the lymph before it returns to the bloodstream
14 The Immune System Acquired Immunity Defending against a specific pathogen by gradually building up a resistance to it.Passive = acquired naturally when antibodies are transferred from mother to unborn child through the placentaActive = acquired artificially when induced by vaccines
15 Click on image to play video. Nonspecific defenseClick on image to play video.
16 Click on image to play video. Cellular immunityClick on image to play video.