Blood is an important part of human body. Ever imagined why our blood, which is actually red in color, turns blue in veins? Well, it's because of the oxygen.
According to experts, heart pumps blood to the lungs to pick up oxygen.
The oxygen-rich blood is then pumped out to the body through arteries, which is red in color, reports Live Science.
Then from arteries, the blood flows through tiny blood vessels called capillaries, where it gives up its oxygen to the body's tissues.
When the blood lacks oxygen it turns blue and returns to heart through veins.