Unit 10 Chapter 39 Immunity from Disease

The Nature of Disease Pathogens Disease producing agents, such as, bacteria, viruses, protozoans, fungi & other parasites Infectious disease Any disease caused by the presence of pathogens in the body

The Nature of Disease Koch’s postulates of 1884 (a procedure to establish the cause of a disease) 1) A pathogen must be found in the body of a sick organism 2) The pathogen must be isolated & grown in the lab to produce a culture 3) When the cultured pathogen is placed in a new host, it should cause the same disease 4) The pathogen should be isolated from the new host and shown to be the original pathogen

The Nature of Disease Endemic disease Disease that are constantly present in a population (ex: common cold) Epidemic When many people in a given area are affected with the same disease at about the same time (ex: influenza)

The Nature of Disease Antibiotics Substances produced by microorganisms that, in small amounts, will kill or inhibit the growth & reproduction of other microorganisms Ex: Penicillin, an antibiotic produced by a fungus, has been in use for over 50 years; many microorganisms are now resistant to penicillin

The Immune System Innate Immunity Your body’s own built-in defense system First (& best) line of defense: Unbroken skin Body secretions, such as mucus, tears, sweat, & saliva

The Immune System Second line of defense is inflammatory response: Fever= increased body temperature slows or stops the growth of pathogens Phagocytes = white blood cells, such as macrophages, that destroy pathogens Interferon = proteins that protect cells from viruses

The Immune System Third line of defense is cellular immunity: Lymphocytes are types of white blood cells that defend the body against foreign substances T cells are lymphocytes that defend against abnormal cells & pathogens inside livings cells B cells are lymphocytes that provide immunity against antigens & pathogens in the body fluids

The Immune System Lymph Tissue fluid (to bathe, nourish cells) after it enters the lymph vessels that will return it to the blood Lymph nodes Glands that filter pathogens from the lymph before it returns to the bloodstream

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 placenta Active = acquired artificially when induced by vaccines

Click on image to play video. Nonspecific defense Click on image to play video.

Click on image to play video. Cellular immunity Click on image to play video.