Human blood is red because of the protein hemoglobin, which contains a red-colored compound called heme that’s crucial for carrying oxygen through your bloodstream. Heme contains an iron atom which binds to oxygen; it’s this molecule that transports oxygen from your lungs to other parts of the body.
Chemicals appear particular colors to our eyes based on the wavelengths of light they reflect. Hemoglobin bound to oxygen absorbs blue-green light, which means that it reflects red-orange light into our eyes, appearing red. That’s why blood turns bright cherry red when oxygen binds to its iron. Without oxygen connected, blood is a darker red color.
Carbon monoxide, a potentially deadly gas, can also bind to heme, with a bond around 200 times stronger than that of oxygen. With carbon monoxide in place, oxygen can’t bind to hemoglobin, which can lead to death. Because the carbon monoxide doesn’t let go of the heme, your blood stays cherry red, sometimes making a victim of carbon monoxide poisoning appear rosy-cheeked even in death.
Credit : The conversation
Picture Credit : Google
