Esteban J Juan George Silva The Immune System Esteban J Juan George Silva

Introduction A person’s body is exposed to many pathogens in daily life, but our bodies rarely get sick. How is that possible? It is because of the immune system . This system is composed into many parts and it communicates with every other system in the body to help fight disease and keep a person healthy.

The body’s defenses Every day, you must wash your hands often to get rid of pathogens. But sometimes that is not enough. That is when a pathogen encounters the body’s first line of defense. These includes skin, saliva, hair, mucus and stomach acids. These are very effective against all types of pathogens. Skin keeps dirt and germs off your body. Believe it or not, sweat also kills some bacteria and keeps them out. Mucus helps trap the pathogens and dirt a person might inhale. Yet all of these measures are nonspecific, meaning that they attack and try to prevent anything from getting into the body.

Picture and description The picture shown shows all the first line defenses of the human body.

Second line defenses The second line of defense are also nonspecific, attacking any pathogen coming their way. This defense is composed by white blood cells and inflammation. White blood cells are made in the bone marrow, which is what is in the middle of our bones. These flow in our blood and attack bacteria in blood vessels. Some attack the bacteria directly while others release proteins to make it easier to kill a pathogen, or directly releasing proteins to kill bacteria.

Inflammatory reaction process

Third line defenses This third defense is specific against foreign substances entering the body. Even though they are different, all the defenses work together. This includes the antibodies and antigens. Antigens cause an immune response and the antibody is the one that attaches to an antigen making it useless. The antibodies are made from two cells: b cells and t cells which both originate from the bone marrow. Allergies come from an extreme sensitivity to antigens entering the body, treating things such as dog or cat hair as antigens and causing increased mucus and inflammation response.

Picture and description What is show in this picture are the third line defenses. As you can see, the antibodies that were produced by the b cells respond to the antigen released by the pathogen.

Immunities Immunity is an ability to resist certain pathogens, and there are two types: active and passive immunity. Active immunity is when a pathogen enters the body and it quickly responds to it, making it useless. You can get active immunity after you get an illness or infection, the antibodies used to cure you stay in your body so you are immune to that disease. Active immunity can also be acquired by vaccination. That is an injection of weakened or dead pathogens so the body can create antibodies. Passive immunity is when antibodies are injected into the body or are passed from generation to generation.

Effects of vaccination over years What this table shows is that the diseases that used to be common before, but now thanks to vaccinations there are less reported cases of these diseases.

Immune system and Homeostasis The immune system has a major role in the homeostasis of the body, because it keeps illnesses and infections from damaging the human body, while working with the circulatory, respiratory and lymphatic system.

Special activity: Immune System Capture the flag In this activity the entire group would be divided into two groups. One group will be the antigens and another group will be the antibodies. There would be two cones, one for each team. The objective of the game is to capture your enemy’s cone and return it to your base, who ever does that first wins the game. If the immune cells capture the pathogen’s cone and return it to base they would win and the person doesn't get sick. If it’s otherwise the pathogens win and they make the person sick.

Video http://www.youtube.com/watch?v=IWMJIMzs EMg

Assessment Time We will now hand out the assessment we prepared for this activity.

Bibliography Science book Pg. 610-618 Googleimages.com