Blood is always raid right? Wrong. Blood comes in a variety of colors. It may be raiding humans and in other mammals, but in octubus for example, have blue blood. And oscillated icefish have blood that is completely clear. In Papua New Guinea, they are green blooded shank. So don't be fooled into thinking blood is always raid. In this video we are going to discover what blood is made of and the roles of the different components. Blood consists of red blood cells, white blood cells, platelets and plasma. 55% of our blood is this pale yellow sticky liquid called plasma. Plasma is mainly made up of water and proteins. Plasma carries nutrients, hormones and proteins around the body and it also just distributes heat around the body so it is pretty important. However this is not the part that makes blood red, green, blue or clear. Plasma equals about 92% water and just under 8% plasma. About 45% of our blood is made up of red blood cells. Red blood cells are tiny by concave disc shaped cells known as erythrocytes. They are made in the bone marrow and contain a special ion containing protein called hemoglobin. Hemoglobin is what enables our red blood cells to carry oxygen around the body and it is hemoglobin that makes our blood red. Octopus have a different special protein called hemocyanin which makes their blood blue. And the icefish doesn't have either hemoglobin or the homocyanin which is why the blood rhymes clear. Watch our video on red blood cells to learn more about these important bio-canocave discs. White blood cells and platelets make up less than 1% of our blood. White blood cells are warriors. They protect our body against invasion from disease causing organisms known as pathogens. Eat liver little cells, do this in two ways. 70% of our white blood cells are phagocytes and engulf the foreign pathogens in a process known as phagocytosis or the others are lymphocytes which produce antibodies. Antibodies bind to the foreign pathagon and stop it from invading further. You will learn more about white blood cells when learning about disease and how our body defend itself against pathogens. And finally platelets. Platelets make a tiny fraction of our blood. They help the blood to clot when you cut yourself, stop in the bleeding and prevent in the wound from becoming infected. From this video you should know that blood isn't necessarily red and the color depends upon what the red blood cells are made up of. Blood consists of the nutrient and the heat transporting plasma. The oxygen carrying red blood cells. And then less than 1% is made up of a very important pathogen fighting white blood cells. And lastly the blood clotting platelets.