Is your blood red or blue?

Human blood is definitely not blue. This is a common misconception that comes from looking at the 'blue' veins in the skin and anatomy charts. The color in blood comes from hemoglobin, a protein that carries oxygen. When there is lots of oxygen in the blood, the hemoglobin turns a little brighter red. When blood is in your veins (that are mostly red too), and is de-oxygenated and carrying wastes from the body tissues, it is a very, very dark red. It only seems blue when you look through your skin because the skin and blood reflect light differently and make the veins and venous blood seem blue looking through light colored skin. If you were to look inside someone, their veins and arteries and the blood inside them would look very similar, not blue at all. Blue is only a reflective property of the skin and underlying veins. Arteries would look just the same if they were close enough to the surface to see like veins.