Communicable Diseases: Diseases that are spread from one person / animal to another.

Germs/Microorganisms/ Pathogens: Tiny living creatures that cause disease.

Bacteria Most common of all pathogens 100 million will fit on a grain of sand Most do not cause disease Reproduces through cell division Treated with antibiotics Examples of diseases caused by bacteria: strep throat, gonorrhea, Lyme disease, MRSA (Methicillin-Resistant Staphylococcus aureus).

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Strep Throat

Virus All viruses are considered parasites Smallest and simplest of all pathogens Can only live in living cells – tricks human cells to reproduce more viruses (reproduce every 20 minutes) Reproduce until “cell bust” Examples: chicken pox, cold, flu, measles, rabies, HIV/AIDS

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Viruses attack certain parts of the body Rabies – brain Polio – central nervous system (CNS) Chicken Pox, Mumps – skin Cold/Flu – respiratory system

Protozoa Most are harmless One celled organisms Grows in water Multiplies very quickly in moist places Examples: diarrhea, malaria wMVo wMVo

Fungi Saprophytes- meaning that they live off of non-living things One celled or multi-cellular plants such as yeasts, molds & mushrooms Live in warm, moist places examples: athlete’s foot and ringworm

Athlete’s Foot

Fungi Ring Worm

Body’s Defense Against Communicable Diseases 1. Skin- most important, it keeps out most harmful germs, produces sweat that kills some type of pathogens (germs). 2. Mucus Membrane- cells that line the nose, throat and mouth. They produce mucus to trap harmful germs so they do not enter the body.

Body’s Defense Against Communicable Diseases 3. Cilia- tiny hairs that move in a wavelike motion to sweep out harmful microorganisms. 4. Fever- normal body temperature is Your body raises its temperature to slow down the multiplication of microorganisms.

Body’s Defense Against Communicable Diseases 5. White Blood Cells- cells in your body that fight infection. They kill pathogens by surrounding them and swallowing them. 6. Chemical Barriers- tears and saliva. 7. Reflexes- blinking, coughing, and sneezing.

Body’s Defense Mucus Membrane CiliaSkinFever Chemical Barriers White Blood Cells Reflexes

Ways that disease enters the body MouthEyesNoseEars Break in Skin Genitals

How Microorganisms are Spread Direct Contact: touching an infected area of another person. Indirect Contact: sneezing, coughing, sharing personal items. Contact with Animals: insect bites, dog bite, bat bite. Other Contact: eating contaminated food.

White blood cells Many different white blood cells work together to protect us against disease-causing germs.

Macrophages: When a germ invades our bodies, macrophages gobble up the germ and display its surface shape, or antigen, for other immune cells to see.

Helper T cells: direct the defense by spotting the foreign antigen on the macrophage and begin to multiply. They alert other white blood cells and direct the body's defense.

B cells: make chemicals called antibodies. Antibodies lock onto foreign antigens making it easier for other immune cells to destroy them.

Killer T cells: Alerted by helper T cells, killer T cells multiply and destroy the invading germs.

Definitions Vaccine: medicine that contains weakened or dead pathogens that cause a certain disease. Antibiotic: substance used to kill/control infectious disease by prescription. Antiseptics: chemicals used to kill germs on contact.