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Defending Infection. Homework Due Thursday. Complete 35.2 Worksheet. Pathogens. Spread of diseases. Different for different diseases Sneezing Coughing Physical contact Exchange of body fluids Infected animals Droplets in the air/doorknobs WASH YOUR HANDS!. Symbionts vs. Pathogens.
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Homework Due Thursday • Complete 35.2 Worksheet
Spread of diseases • Different for different diseases • Sneezing • Coughing • Physical contact • Exchange of body fluids • Infected animals • Droplets in the air/doorknobs • WASH YOUR HANDS!
Symbionts vs. Pathogens • Symbionts are harmless to the body • Sometimes beneficial • Bacteria in the Large Intestines help with digestion • “Good guys” grow and reproduce without causing problems • “Bad guys” cause problems • Destroy cells of their host • Release poisons that kill host cells • Worms might block blood flow or take nutrients
First Line of Defense • Dead cells! • Skin make penetration of pathogens very difficult • Acts as “armor” to defend the body • Holes in your “armor” include: • Mouth • Eyes • Nose
First Line of Defense • Saliva, mucus and tears contain lysozyme • Enzymes that breaks down bacterial cell walls • Mucus traps pathogens in nose and throat • Cilia push the trapped pathogens to the stomach where they are swallowed.
Inflammatory Response • Infected areas become red and painful • Pathogens stimulate cells to release histamines • Increase blood flow and nutrient fluids • Swelling occurs when fluids leak from expanded blood vessels • How does this compare to sprained ankle? Or a broken finger?
Inflammatory Response • White blood cells move into infected tissues • Phagocytes are WBCs that engulf (eat) and destroy bacteria • Interferons? • Interfere with the growth of viruses • Don’t allow synthesis of viral cells • Fever • Slows pathogens and speeds up immune system
Immune System • Basis is to differentiate between domestic and foreign • Domestic signals notify the Immune System they are good for the body • Foreign objects are unable to replicate password • Recognizing “self” is vital to the success of the Immune System
Immune System • Must be able to respond to “non-self” • Remembers any specific invader • Immune system memory allows for the Immune System to respond to it quicker next time • Example: Ability to do “Times Tables”
Immune System • Antigens are foreign substances that trigger the immune system • Antibodies are created to “tag” specific antigens to be destroyed by phagocytes
Homework Due Thursday • Complete 35.2 Worksheet