The apparent coloration of blood vessels beneath the skin often elicits curiosity. While blood itself is red due to the presence of hemoglobin, the oxygen-carrying molecule containing iron, the visual perception of veins as green or blue is an optical illusion. This phenomenon arises from the interaction of light with skin and subcutaneous tissues.
This perceived hue, although not the true color of the blood within, is significant in understanding how light interacts with the body. Factors such as the scattering of light by the skin, the absorption of different wavelengths, and the depth of the vessel all contribute to the final perceived color. Historically, this misconception has been reinforced by anatomical illustrations and descriptions, often simplifying complex physiological processes.