Why does hemoglobin make blood red?

Answer 1

Blood contains a protein called hemoglobin. Hemoglobin, which contains iron, is found in red blood cells and is the ingredient that makes blood red. Hemoglobin transports oxygen from the lungs to wherever it's needed throughout your body. You've probably noticed that sometimes blood is bright red, while other times it is dark red. The difference in color comes from the changing amounts of oxygen in the blood. Arteries, a type of blood vessel, carry blood away from the lungs and heart to the rest of your body. That blood is rich in oxygen, which joins with hemoglobin to give the blood its bright red color. Tiny blood vessels called capillaries, which have narrow walls through which tiny substances can pass, distribute oxygen and nutrients to all of your body's cells.