Unit 6 Disease & Illness
Causes of Infectious Diseases Infectious Disease (Communicable Diseases): Are caused by organisms or viruses that enter and multiply with the human body. Your body & environment are filled with Microorganisms(only visible with a microscope). Not all of them cause diseases. You have millions that live in your mouth, skin, and digestive track). Pathogens: Small microorganisms that invade & attack body tissue. (There are many types of pathogens). Parasites Organisms that live in another organism and get nourishment from it. Bacterium Single-celled organism / can live almost anywhere / harmful to human cells
Causes of Infectious Diseases Cont.. Virus Smallest known type of infectious agent. (100 times smaller than most bacteria). Viruses take over a living cell – damage or kill it. Protozoans Single-celled organisms that are much larger and more complex than bacteria. Have the ability to move through fluids in search of food. (example: Malaria(affects red blood cells: causing weakness & nausea); Amebic Dysentery(stomach pain & diarrhea) Fungi Organisms that can’t make their own food (yeasts, molds, and mushrooms). Grow in warm, dark, moist areas. (Examples: athlete’s foot, ringworm)
How Infectious Diseases are Spread Transmission Direct Contact Uninfected person comes into physical contact with an infected person Examples: STD’s (sexually transmitted diseases); Kissing (cold sore); Shaking hands Indirect Contact Enter lungs / tiny droplets are exhaled, coughed, or sneezed out Examples: Colds, Influenza, TB, measles, mumps, chickenpox
Animals Spread Disease Examples Bite of an infected dog, bat, raccoon – Rabies: a deadly disease of the nervous system Mosquito – Malaria, West Nile Tick – Lyme Disease & Rocky Mountain Spotted Fever
How Infectious Diseases are Spread How Infectious Diseases are Spread Cont… Cont… Environment (Water, Soil, Air, Food) Example: Cholera – a bacterial disease of the digestive system that causes severe diarrhea.
How Infectious Diseases are Spread How Infectious Diseases are Spread Cont… Cont… Contaminated Objects: Eating Utensils & Glasses Toothbrushes Needles (piercing) Towels Items in the school? FACT: About 80%of infectious diseases are spread by hand contact. Washing your hands with soap and water is a simple and effective way to prevent the spread of colds & flu.
Physical & Chemical Defenses Physical & Chemical Defenses Skin Skin: Microorganisms usually cannot get through your skin. cuts, scrapes, burns and other injuries can lead to infection. Mucous Membranes Mucous Membranes: protective lining of the mouth, eyes, and nose CiliaCilia: : Tiny hair-like structures Saliva & Tears Saliva & Tears: Contain chemicals that attack pathogens Digestive System Digestive System: Chemicals & acids that harm & kill invading bacteria. InflammationInflammation:
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