The colour blood red is a dark shade of the colour red meant to resemble the colour of human blood (which is composed of oxygenated red erythrocytes, white leukocytes, and yellow blood plasma). It is the iron in hemoglobin specifically that gives blood its red colour. The actual colour ranges from crimson to a dark brown-blood depending on how oxygenated the blood is, and may have a slightly orange hue. Deoxygenated blood, which circulates closer to the body's surface and which is therefore generally more likely to be seen than oxygenated blood, issues from bodily veins in a dark red state, but quickly oxygenates upon exposure to air, turning a brighter shade of red. This happens more quickly with smaller volumes of blood such as a pinprick and less quickly from cuts or punctures that caus