A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

If blood is red, why do veins look blue?

Best Answers

Blood is always red, actually. Veins look blue because light has to penetrate the skin to illuminate them, blue and red light (being of different wavelengths) penetrate with different degrees of success. What makes it back to your eye is the blue light. Meanwhile, here's what happens to the blood in your body:. read more

They aren't actually blue, but there are reasons why veins look that way: Skin absorbs blue light: Subcutaneous fat only allows blue light to penetrate skin all the way to veins, so this is the color that is reflected back. read more

Blood is always red, actually. Veins look blue because light has to penetrate the skin to illuminate them, blue and red light (being of different wavelengths) penetrate with different degrees of success. read more

So, if a vein is close to the surface of the skin, most of the blue light will be absorbed, and even though red light doesn't reflect as much, the red light:blue light ratio is high enough to make the vein appear red. With deeper veins, the blood doesn't absorb as much blue or red light. read more

They aren't actually blue, but there are reasons why veins look that way: Skin absorbs blue light. Subcutaneous fat only allows blue light to penetrate skin all the way to veins, so this is the color that is reflected back. read more