1. HOW DOES INFECTION OCCUR?

2. Key Terms 1. Microorganisms = small, living organisms not visible to the naked eye 2. Pathogens = microorganism that cause disease 3. Susceptible Host = an organism capable of contracting a specific disease

3. Types of Pathogens o Fungi o Bacteria o Viruses o Protozoans o Prions

5. Bacteria o Single-celled organisms o Live in a variety of environments o Only 1% cause disease o Usually killed by antibiotics o Examples of diseases caused by bacteria: 1. Pneumonias 2. Strep throat 3. Tuberculosis

6. Viruses o Smallest of pathogens o Viruses can reproduce only by invading a host cell o NOT cured by antibiotics o Examples of diseases caused by viruses: ◦1. Chicken pox ◦2. Colds ◦3. Flu (influenza) ◦4. Small pox ◦5. HIV

7. Types of Infection Endogenous = infection or disease originates within the body Examples: 1. Metabolic disorders 2. Birth defects 3. Tumors

8. Types of Infection Exogenous = infection or disease originates outside the body Examples: 1. Pathogenic organisms 2. Radiation 3. Chemicals 4. Trauma 5. Electric shock 6. Temperature extremes

9. Types of Infection Nosocomial = infections acquired by an individual in a healthcare facility o Usually present in the facility and transmitted by healthcare workers to the patient Opportunistic = infections that occur when the body’s defenses are weak

10. Common Body Defenses 1. Mucous membrane: lines the respiratory, digestive, and reproductive tracts 2. Cilia: tiny hair-like structures that line the respiratory tract to propel pathogens out of the body 3. Coughing and sneezing 4. Hydrochloric acid: destroys pathogens in the stomach 5. Tears in the eye: contain chemicals that kill bacteria 6. Fever: kills pathogens via heat 7. Immune response: body produces white blood cells and antibodies to fight pathogens