Week # 18

Communicable Disease 

Pathogens

1. Infectious diseases: caused by organisms or viruses that enter and multiply within the human body. 

2. microorganisms: small disease causing organisms

3.Pathogen: microorganisms and viruses that case disease

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Bacteria: simple single-celled microorganisms. 

• live in air, soil food and in or on the body

• some bacteria injure cells through toxin

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Viruses: 

• about 100 times smaller than bacteria

• can ONLY multiply after entering a cell where they take over and use the cell to reproduce 

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Fungi:

• organisms such as yeast, mold and mushrooms

• Grow in dark, moist, warm places

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Protozoans: single-celled organisms that are much larger and more complex than bacteria. 

• have the ability to move through fluid in search of food

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How Pathogens are Spread:

1. Infected people

2. Infected Animal

3. Contaminated objects

4. Contaminated food/water/soil 

Understand how each of these above examples can spread pathogens. 

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Difference Against Disease: 

1. Physical and Chemical Defenses​

   • skin​

   • mucous membranes

   • cilia

   • saliva and tears

   • digestive system enzymes

2. Inflammation

   • if pathogens get past the physical defense then it begins to injure the cells. ​

   • The body's general response to all injuries is inflammation. 

3. The Immune System

   • Lymphocytes: white blood cells which kill pathogens​

   • Immunity: the body's ability to destroy pathogens that it has previously encountered.

   • T-cells: destroy the body cells which have been infected, produce chemical that make new cells, and turns off the immune system

4. Passive and Active Immunity 

   • Passive immunity= Immunity acquired by receiving antibodies from a source other than one's own immune system. ​Occurs naturally in babies. 

   • Active Immunity = results from either having a disease or from receiving a vaccine

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