1. The Immune System Year 9 Science The Body At War Year 9 Science The Body At War

2. The Battle Lines are drawn There are billions of microbes, such as viruses and bacteria all around us. Some of these microbes are pathogens (recall what that means?) If given the chance, they will invade our bodies because we offer a warm place full of nutrients that allow them to grow and multiply This can cause us to get sick There are billions of microbes, such as viruses and bacteria all around us. Some of these microbes are pathogens (recall what that means?) If given the chance, they will invade our bodies because we offer a warm place full of nutrients that allow them to grow and multiply This can cause us to get sick

3. First Lines of Defense The skin The skin – physical barrier and microbes living on our skin kill any unknown invaders Mucous/fluids Mucous/fluids in our mouth, nose, etc. traps invading particles Cilia Cilia – tiny hairs line our noses and respiratory tracts to remove particles Our best defense is to keep these pathogens out to start with. Some of our first line defenses are:

4. First Lines of Defense Stomach acid Stomach acid – our stomach juices are an unfriendly place for most living things and can kill many invading pathogens Inflammation Inflammation – bacteria can enter our bodies easily through a cut. Dying cells sound the alarm and defensive cells respond to the area through increased blood flow. Stomach acid Stomach acid – our stomach juices are an unfriendly place for most living things and can kill many invading pathogens Inflammation Inflammation – bacteria can enter our bodies easily through a cut. Dying cells sound the alarm and defensive cells respond to the area through increased blood flow. Sometimes, the pathogens are able to penetrate our bodies through our mouth or an open cut. Then we have additional weapons at our disposal

5. The Immune Response When the first lines of defense don’t work, we have an army of cells that work to kill the invaders White Blood Cells Needed to Defend the Body Today! Sign up now if you are a: Phagocytes (eaters)Phagocytes (eaters) GranulocytesGranulocytes MacrophagesMacrophages LymphocyteLymphocyte T-cellsT-cells B-cellsB-cells Sign up now if you are a: Phagocytes (eaters)Phagocytes (eaters) GranulocytesGranulocytes MacrophagesMacrophages LymphocyteLymphocyte T-cellsT-cells B-cellsB-cells

6. Phagocytes (the eaters) Granulocytes These white blood cells are the first responders to an attack, such as in a cut. These white blood cells are the first responders to an attack, such as in a cut. These cells “eat” invaders until they themselves die. These cells “eat” invaders until they themselves die. The pus of a wound is mostly dead granulocytes The pus of a wound is mostly dead granulocytes Macrophages These white blood cells are the “big” (macro) “eaters” (phage). These white blood cells are the “big” (macro) “eaters” (phage). They are slower to respond, but are longer –lived. They are slower to respond, but are longer –lived. These cells patrol the blood stream looking for unfamiliar cells which they engulf (eat) These cells patrol the blood stream looking for unfamiliar cells which they engulf (eat) These cells are made in our bone marrow

7. The Lymphatic System The parts Thymus Lymph nodes Spleen Lymph vessels Thymus Lymph nodes Spleen Lymph vessels It’s mission Storage and transportation of Lymphocytes that are used in the immune response Removal of dead cells including invaders Storage and transportation of Lymphocytes that are used in the immune response Removal of dead cells including invaders

8. T-Lymphocytes T-cells mature in the Thymus. There are two types:

9. T-Lymphocytes T-cells mature in the Thymus. There are two types:

10. B-Lymphocytes Plasma Cell Produces Y-shaped antibodies that attach to the pathogen. Produces Y-shaped antibodies that attach to the pathogen. This helps them to clump together to be eaten by a macrophage This helps them to clump together to be eaten by a macrophage Antibodies are made quickly and can also prevent viruses from invading cells and neutralise toxins released Antibodies are made quickly and can also prevent viruses from invading cells and neutralise toxins released Produces Y-shaped antibodies that attach to the pathogen. Produces Y-shaped antibodies that attach to the pathogen. This helps them to clump together to be eaten by a macrophage This helps them to clump together to be eaten by a macrophage Antibodies are made quickly and can also prevent viruses from invading cells and neutralise toxins released Antibodies are made quickly and can also prevent viruses from invading cells and neutralise toxins released Memory Cell Once an invader has been in the body, these cells are able to recognise them quickly the next time Once an invader has been in the body, these cells are able to recognise them quickly the next time When recognised, they trigger a faster immune response When recognised, they trigger a faster immune response There are also some Memory cells produced by T-cells There are also some Memory cells produced by T-cells Once an invader has been in the body, these cells are able to recognise them quickly the next time Once an invader has been in the body, these cells are able to recognise them quickly the next time When recognised, they trigger a faster immune response When recognised, they trigger a faster immune response There are also some Memory cells produced by T-cells There are also some Memory cells produced by T-cells B-Cells work by recognising specific antigens using their receptors. When it finds a match, it is activated by a Helper T and splits into two types:

11. Macrophages The Immune Response – a pictorial representation

12. Cool caricatures from: http://nobelprize.org/educational/medicine/immunity/immune-detail.html