Section 4

 Objective  You will understand the functions of various body systems.

 Have you ever had a cold?  How do you know when you are sick?  How do you avoid getting sick?

 Purpose  You are going to read about how the body protects itself from becoming ill. We are going to understand cause-and-effect relationships between the disease-causing pathogens and the body’s immune system.

 Summary  Microorganisms can cause disease if they are able to enter the body.  The body has several means of defense in the skin, nose, mouth, and throat to prevent disease- causing microorganisms from entering the body.

MouthNoseLungsStomach How do these organs protect the body?

 Questions  What are some of your body’s defenses against invading microorganisms.  What is the purpose of your tears?  Why are acids that are found in the stomach and sweat important?  What might happen if the mucus in your nose, throat, and lungs suddenly dried up?

 Objectives  You will know that pathogens can cause infectious diseases and how some diseases are spread.

 Summary  Pathogens, such as bacteria and viruses, can cause infectious diseases including strep throat, colds, and influenza.  Some diseases are spread through the air and some through direct contact with pathogens.  lems/biosphere/ lems/biosphere/  aynext=1&list=PL3DD295F C5 aynext=1&list=PL3DD295F C5

 Questions  What is an infectious disease?  What are two pathogens that cause disease?  How are bacteria and viruses the same? How are they different?  What causes a person to become ill with strep throat?

 Objective  You will understand the functions of various body systems.

 Summary  Certain types of blood cells and antibodies that fight against infectious pathogens are part of the immune system.  Vaccines trigger antibody production, providing immunity against specific pathogens.

 Questions  What are antibodies?  Explain how a vaccine causes immunity.  How does a vaccine protect against disease?  Are all white blood cells the same? How do you know?  If you have had chicken pox, what is the risk level that you will get it again after you come in contact with someone who has the illness?