Source: Healthline
The blood inside your veins is dark red. So, many people wonder why veins look green or blue through the skin instead of red.
Veins are types of blood vessels. The other blood vessel types are capillaries and arteries. Blood vessels help transport blood and nutrients throughout your body.
The job of most veins is to carry oxygen-depleted blood from bodily tissues back to your heart. Your pulmonary artery brings your blood to your lungs, where it receives a fresh supply of oxygen. Your arteries then carry the oxygenated blood to your tissues and organs. In this article, we’ll explain why veins can look green or blue, particularly through lighter-colored skin. We’ll also go into detail about vein symptoms that require medical attention.
Why do veins look green?
There are three types of veins: deep veins, pulmonary veins, and superficial veins. Superficial veins are the type that you can see.
They may look green instead of red because the color green has a shorter wavelength than the color red. They may also look blue or blueish-green because blue also has a shorter wavelength than red.
The electromagnetic spectrum contains wavelengths, or visible light that your eye can see. The colors of visible light range from red to violet in this order: red, orange, yellow, green, blue, violet. Red has the longest wavelength, lowest frequency, and least amount of energy.
What we perceive as “color” is actually the frequencies of the visual light spectrum that are reflected from a surface while other waves are absorbed. For instance, a green leaf reflects the green waves and absorbs the other colors, which is why we see it as green.
The illusion of “green” or “blue” veins occurs because you’re viewing them through layers of skin and tissue, which absorb more of the red frequencies while allowing higher frequency waves to reach your eyes.
Superficial green veins may be most visible on specific parts of your body and face such as:
backs of hands
shins
thighs
abdomen
chest
forehead
neck
Green and blue veins can also be seen where your skin is thin. Skin can become thinner and less elastic with age, making veins appear more prominent. Also, the less fat you have, the more your veins may show, regardless of your age.
Other reasons why veins may be more visible
Here are some other reasons why veins may appear more prominent:
Genetics can play a role in how visible your veins appear. For example, if one of your parents has noticeable veins, you may have them as well.
Emotion can also have an effect. If you’re angry, yelling, or laughing uproariously, an increase in pressure may make your veins expand and bulge. This may be most likely to occur on your forehead, temples, and neck. Sneezing can also have this effect.
Exercising can also raise blood pressure, making veins more prominent.
Heat and hot weather can cause veins to expand and dilate, making them more visible.