This is the reason why blood is red.

Although we know the term blue blood for those from noble families. In reality humans have blood with a red color, regardless of race or social status. Then why the blood is red ???

Health expert Jonathan Polley mentioned that actually inside our body there are different blood color difference. Indeed, this difference is not so clear because basically the blood remains red. In organs such as lungs, as long as we do not smoke and keep a healthy lifestyle, the color of the blood inside should be pink. Meanwhile, blood in the liver organ usually tends to be brownish or grayish. Blood present in blood vessels is what we know as red. Polley says that the main blood component is plasma. But the color of the blood plasma is very pale and can be influenced by other colors. Many people think if the cause of the color of red blood cells rich in hemoglobin and this protein is due to the presence of iron. Though this is not true, the cause of red blood color is the existence of a sub unit of protein called "heme". This heme is able to bind iron present in hemoglobin. Whereas oxygen is also bound to this iron. The interaction between the heme and oxygen groups is what makes the blood red. If the hemoglobin levels carry oxygen in very large quantities, then hemoglobin will tend to absorb darker colors, making the red color darker. Meanwhile, if the content of carbon dioxide in the blood quite a lot, then the color tends to be blue or purplish.