 Why is our blood important? Pause the video here and try to think of some ideas. Our blood has many important functions which can be stated simply as transporting substances around our body and protecting us from disease. Sometimes though, our blood doesn't work in exactly the way it should. In this video, we will look at an example of this, anemia. Our blood is made of plasma, platelets, white blood cells, and red blood cells. If a blood sample is centrifuged, i.e. spun round very fast, in blood fractionation, this is what the sample would look like. As you can see, most of the cells in the blood are red blood cells, and it's these cells that make the blood look red. Here is a basic diagram of a red blood cell or erythrocyte. Anemia affects this type of cell. Every cubic centimetre or milliliter of blood contains five billion red blood cells. They are very small. Each one is only an average of seven micrometres in diameter. One micrometre is a millionth of a metre. Red blood cells have several adaptations for carrying as much oxygen as possible around the body. The biconcave disc shape means that it has a larger surface area. They are flexible, so they can move easily through small capillaries. And you may notice from the picture that it's missing an organelle, a cell part that almost all other eukaryotic cells have. Pause the video and see if you can think what it is. It has no nucleus. This means they have more room for oxygen, which is carried by hemoglobin molecules. Anemia is the general term for having either fewer red blood cells than normal, or having an abnormally low amount of hemoglobin in each red blood cell. There are several different types of anemia, and each one has a different cause. In this video, we will discuss two. Pernicious anemia occurs when a lack of vitamin B12 or folate causes the body to produce abnormally large red blood cells that can't function properly. Sources of vitamin B12 include fish, cheese, chicken, eggs, red meat, milk, and almonds. Iron deficiency anemia, the most common type, is when there is a lack of iron in the body, perhaps from a diet that is low in iron or because of blood loss or pregnancy. People who have particularly heavy periods are susceptible to this type of anemia. Symptoms can include tiredness and lack of energy, shortness of breath, noticeable heartbeats or heart palpitations, and pale skin. This is all because the red blood cells that are made are smaller than normal and sometimes irregular in shape, meaning each cell can carry less oxygen. They will also appear paler when looked at under a microscope and the symptoms are produced because the person's body cells do not receive enough oxygen for respiration. Doctors sometimes prescribe iron tablets if someone is suffering from iron deficiency anemia. Sufferers could also increase the amount of iron in their diet. Foods that are rich in iron include artichokes, egg yolks, red meat, dark greens, dried fruits and legumes. So now you know what red blood cells do and how they are adapted. You have also learned about two types of anemia and how they may be treated. Please like and share our videos with your friends. If you have any questions that you want help with, just comment below.