Subtitles section Play video Print subtitles It's AumSum Time. Why do blood types matter? Because burger types matter. No. Usually, our blood is classified into 8 types, namely. A positive, A negative, B positive, B negative. AB positive, AB negative, O positive and O negative. This classification is based on the. Presence, absence or combination of specific antigens on our red blood cells. If we have A antigen, then our blood type is A. If we have B antigen, then our blood type is B. If we have both antigens, then our blood type is AB. And lastly, if we neither have A nor B, then our blood type is O. The positive and negative factor is determined by the RhD antigen. If we have RhD antigen, then we are Rh-positive, otherwise we are Rh-negative. But what is the use of these blood types? Our immune system produces antibodies against the antigens we don't have. So, during transfusion, if wrong blood is injected. Our antibodies will recognize the unknown antigen. As an invader and start attacking it. This can cause transfused blood to clot which can be potentially fatal. What is blood pressure? It's a form of acupressure. No. In order to deliver oxygen and nutrients. To each and every cell of our body. Our heart pushes blood through tubes called blood vessels. As the blood moves, it exerts force on the vessels' walls. The measurement of this force of blood on the walls is called blood pressure. The ideal blood pressure reading is. About 120 over 80 millimeters of mercury or slightly below it. But why does the reading have 2 numbers? It is because our heart is constantly contracting and relaxing. During a phase called systole. Our heart contracts to push the blood through arteries. Thus increasing the pressure. So, the bigger number indicates the systolic blood pressure. Whereas during diastole, our heart relaxes, decreasing the pressure. So, the smaller number indicates the diastolic blood pressure. Blood Rain. Relax. Blood rain has red colored water droplets. There are various reasons behind this. Around Sahara Desert. Brownish dust and sand carried by storms mix with water droplets in clouds. Giving rain its brownish red color. In Kerala, red spores of algae called Trentepohlia Annulata. Got carried by wind and mixed with water droplets, causing blood rain. While, in Zamora, Haematococcus Pluvialis algae got caught in rainclouds. Got stressed and produced a red pigment called astaxanthin. Causing blood rain. Why is blood red in color? Because everyday it bathes using red paint. No. Our blood mainly consists of. A liquid called plasma, red blood cells, white blood cells and platelets. However, the color of our blood is basically because of red blood cells. Each of the red blood cells contains hemoglobin. Hemoglobin is an iron rich protein. When hemoglobin binds with oxygen. The interaction between them gives our blood its red color. Moreover, like human beings, not all animals have red color blood. This is because the blood of some animals. Such as octopuses, spiders, etc. has hemocyanin instead of hemoglobin. Hemocyanin is a copper containing protein. When hemocyanin binds with oxygen, their interaction gives the blood a blue color. The blood of some lizards has biliverdin instead of hemoglobin. Which give their blood a green color.