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Why are veins blue if blood is red

by Alivia Nyhan
Published: Last Updated on

In the arm, in the hands, in the neck, in the temples, or even the varicose veins, wherever we look, our veins are bluish. This makes many people wonder why they appear this color if the Blood is red. The first logical answer might be to think that the veins are blue, but we have already advanced that they are not. So why are veins blue if Blood is red? If you want to know the answer in the following FastlyHealarticle, we will explain it.

Why are veins blue if Blood is red

The Blood is red, which we all have clear, and we have been able to verify reliably. So how is it possible that we see blue veins? Are they blue? The truth is that we do not see all veins blue; some we see purple, others more reddish and others of a more greenish tone, be that as it may, everything has an explanation.

The reason we see blue veins is an optical illusion. We only see blue those veins that are more superficial, those located half a millimeter below the skin, for example, the vein that crosses the arm and where they draw Blood.

The fact is that the spectrum of light is made up of different wavelengths, and each length corresponds to a different color. When the light hits our skin, the most extended measurements reach the deepest, while those that remain on the surface are the shortest. Considering that the longest waves are those of the red color and the shorter ones are those of blue color, we have the answer to why we see the blue veins and why, precisely, they are the most superficial. The thinner a person’s skin and the less subcutaneous fat, the closer the veins are to the surface, the bluer they will appear.

We have already explained that the superficial veins are the ones that we see blue, or rather, they are the ones we see. But what are they? We must say that the veins of our body can be separated between those of the deep venous system and the central venous system:

  • The deep venous system carries more than 90% of the blood flow and feeds the muscles and most of the body’s functions.
  • Superficial venous systems do not reach 10% of the blood flow, but they are all that we can see and feel. They are those that are located just under the skin.

Why are arteries red and blood blue

But the location of the veins is not the only reason, there is another that makes us see the blue, and that is that, unlike the arteries, the veins are a little more bluish. The reason is that the Blood that passes through the streets is full of oxygen, erythrocytes, and other cells that give it a reddish color, while when it circulates through the veins, they have already been emptied and are somewhat more bluish.

This is what causes that when the double blood circulation system is drawn, the arteries are painted red, and the veins are characterized by blue.

How are the veins

Arteries and veins have different characteristics. To begin with, they are made up of three distinct layers :

  • Intimate layer: the innermost layer, which, among other functions, prevents blood clotting.
  • Adventitious layer: the outermost layer, where nerve impulses occur.
  • Middle layer: the part that can be contracted, thicker in the arteries than in the veins, since in the former, the Blood has more pressure.

How veins work

Cells can contract; however, this contraction occurs involuntarily under certain circumstances. For example, in heat, veins expand to dissipate it, while when it is cold, they contract to maintain temperature.

The same happens depending on the blood pressure, which causes the veins to constrict. This is precisely why when we are stressed, anxious, or getting dizzy; we turn pale: because the veins constrict, and our skin loses the reddish coloration of the Blood.

This article is merely informative, at FastlyHeal .com we do not have the power to prescribe medical treatments or make any type of diagnosis. We invite you to see a doctor in the case of presenting any type of condition or discomfort.

If you want to read more articles similar to Why are veins blue if Blood is red, we recommend that you enter our Blood, heart and circulation category .

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