The Immune System PDF

The immune system 1 Immune system 2 What is immunity? The body's immune system Immunity means that you are protected against something. There Everybody has an inbuilt immune system whi...

The immune system 1 Immune system 2 What is immunity? The body's immune system Immunity means that you are protected against something. There Everybody has an inbuilt immune system which protects it from are different kinds of immunity. This topic is about how different diseases and germs. This system has a lot of different parts which parts of our bodies work together to keep us from getting sick. work together to keep out any harmful germs, and attack and Immunity to some diseases is passed on from our mothers before destroy any which manage to get inside your body. we are born. Immunization (having your 'shots') helps our body's immune defence system protect us from diseases. Every day your body is exposed to millions of germs, and you do not get sick from them because of your immune system. There are several parts to the immune system: The skin, tonsils in the throat, adenoids in the ears, sinuses in the Every time you do get sick because of a germ, your immune system nose, the lungs, the bowel, white blood cells and the lymphatic works to get rid of it and then it remembers how to fight the system. infection if the same germ comes again. Your body is like a castle. It defends you against germs. Usually the older you get, the more germs you become immune to. 1. What is immunity? 1. What does the immune system do? 2. List the parts of the immune system. 2. How does your immune system fight germs? The immune system 3 The immune system 4 The skin Nose, mouth, eyes, ears, lungs and bowel The skin is the first line of defence in your immune system. This is what happens when your nose, mouth, eyes, lungs and bowel You know how you put plastic wrap over leftovers to keep them get attacked by germs or dust: fresh enough for later? Well, your skin is like a plastic wrap to keep germs from getting into your body. The mucous membranes which line the mouth, throat, lungs and bowel, act like a barrier to germs, just as the skin does. The epidermis (outside layer of skin) has special cells which warn the body about incoming germs. Saliva in the mouth and the tears which wash your eyes have special enzymes (chemicals) in them which break down the cell walls of Glands in the skin also make substances that can kill some bacteria many bacteria and viruses. (anti-bacterial chemicals). This means you don't get infections on your skin unless your skin is damaged, such as by a cut or a graze. The mucous that is made in your nose, throat and lungs traps bacteria, viruses and dust. Acid in your stomach kills most germs, and starts to digest your food. What is the functions of the following? 1. Saliva 2. Mucous 3. Stomach acid 1. Draw the structure of the human skin. 2. How does the skin protect us from germs? The immune system 5 The immune system 6 The Lymphatic system Diagram of the lymphatic system The lymphatic system is made up of: Lymph: a clear fluid that is very similar to the clear liquid in blood, but it carries only white blood cells, not red blood cells. The lymph flows through all the parts of the body picking up fluid around cells and carrying it back to large veins near the heart. It also carries white blood cells to the places where they are needed. Lymph nodes Some bacteria or viruses that have entered the body are collected by the lymph and passed on to the lymph nodes where they are filtered out and destroyed. Lymph nodes are sometimes called glands. Your doctor can often tell if you have an infection by checking out the lymph nodes (glands) in your neck and under your arms to see if The spleen clears out worn out blood cells and fights off infection. they're swollen. If they are, it shows that they are working to get rid The thymus trains the T cells (one of the white blood cells) to do of bacteria or viruses. their job of looking out for germs or things that don’t belong in the body, and destroying them. The bone marrow is where the blood cells are made. 1. What is the function of The adenoids keep infection out of your ears. lymph? The tonsils kill germs that may enter the throat. 2. Where are lymph The lymph vessels carry lymph fluid around the body. nodes found? 3. How do they help us? List the functions of the following: Spleen, thymus, bone marrow, adenoids, tonsils. Copy the diagram. The immune system 7 The immune system 8 Facts about blood White blood cells In your blood, you have red blood cells and white blood cells, and in Blood is made up of four parts – plasma, red cells, white cells and platelets. lymph there are white blood cells. Each part has a special job. There are several different types of white cells which work together to seek out and destroy bacteria and viruses. Plasma is a yellow liquid. It helps give you energy and grow. Red blood cells carry oxygen to your cells. All of them start off in the bone marrow, growing from 'stem cells'. The disease-fighting white blood cells are specialists. Some of the White blood cells clean the blood and fight germs. When a virus enters white blood cells are: your body, white blood cells rush to destroy the virus so you get better. Neutrophils, which move around the body in the blood and seek out Platelets help your blood clot. When you cut yourself, a clot forms so the foreign material (things that don't belong in your body). blood stops running. If your blood didn’t clot, you could bleed to death. Macrophages are the biggest blood cells. Some live in different parts of the body and help to keep it clean, e.g. in the lungs. Others swim around cleaning up other white blood cells that have been damaged while doing their jobs, e.g. cleaning up pus that has been caused by neutrophils when they work to clear out bacteria from a wound. Lymphocytes work on bacterial and viral infections There are two different types: B cells produce antibodies. Each cell watches out for a particular germ, and when that germ arrives, the cell starts to produce more antibodies which begin the process of killing that germ. Antibodies attach themselves to the germs so that other cells can recognize that these germs need to be destroyed. T cells look for cells in your body that are hiding invaders (germs) or body cells that are different to normal healthy cells (such as cells 1. What are the four parts of blood? that could develop into a cancer) and kill them. 2. List the function of each. 3. Draw the diagram. List the three types of white blood cells and briefly explain what they do. The immune system 9 The immune system 10 The difference between red blood cells and white blood How does your immune system know which cells to cells attack? Your body has lots of friendly bacteria around it which help your body work properly, e.g. some bacteria inside your bowel help you to digest your food and break it up into the different things that are needed in various parts of the body. These friendly bacteria live on the surfaces of the body, such as on our skin or inside the bowel. They do not try to invade the body, so the immune system does not try to get rid of them. Other germs which cause illness, try to enter the body. Antibodies, which are made by the lymphocytes, attach to the invaders so that the other white blood cells can destroy them. They 'tag' them so they can be easily noticed. As well as attacking germs, your immune system recognizes and The red blood cells are donut shaped and regular. They carry oxygen destroys other cells which do not belong in your body. The cells in around the body. your own body are marked with a special system called antigens. The white blood cells are all different shapes because there are Your immune system can recognize these markings as 'you'. Any different types. They kill bacteria and viruses in your body. cells which do not have the right markings are 'not you' and are therefore attacked. This happens if, for example, you have a blood transfusion with the wrong types of blood cells. Your body's immune 1. Copy the diagram including the labels. system recognizes that these cells do not belong in your body, so it 2. What is the difference in the function of red and white blood destroys them. cells? 1. What do antibodies do? 2. What do antigens do? The immune system 11 The immune system 12 How you know your immune system is working How to build a strong immune system You know your immune system is working: A strong immune system is an immune system that is working well.  if you get better after you are sick This means that when an invader comes into your body, it can be  if cuts heal without getting infected destroyed very quickly. It may mean that you catch a cold  if you don't catch the same diseases over and over again sometimes, but you will be able to get better quite quickly. It may  when you get swollen glands also mean that you don’t catch the cold in the first place because  when you get swelling and soreness around a cut. your immune system destroys the germ as soon as it enters your body. Your immune system is in there working to get rid of any infection. Sometimes the immune system will make a mistake. To stay healthy, we should wash our hands before eating and after It may attack your own body as if it were the enemy. This happens the toilet, so that we don’t get germs coming into our mouths when when a person has an allergy. we handle food or put our hand to our mouth. Allergies are caused by the immune system over-reacting to To build a strong immune system there are certain foods we should something that is not really a threat, like when pollen triggers hay eat. These are fruits, vegetables and other foods from nature. Fruits fever or asthma. containing Vitamin C are particularly good. Examples of these are oranges, lemons, apples and pineapples. When the immune system is damaged, they get lots of infections and are much more likely to get serious illnesses. Their body cannot The foods that make our immune systems weak are foods recognize the infection or abnormal cells very well and the immune containing high sugar and salt, like processed snack foods in packets, system does not destroy them as well as usual. sweets, cakes and biscuits. Make a list of things we can do to build a strong immune system. How do you know if your immune system is working well?