How does blood change colors?

Blood comes in two primary colors: blue when it contains carbon dioxide and red when it contains oxygen.

Hemoglobin's iron molecules have changed color, giving it its red hue.

The chemical makeup of blood, which includes salts, proteins, and platelets, as well as the quantity of iron in the blood, all influence how red the blood can appear.

After my dad broke his thumb in a car door when I was a little child, he ruptured a vein beneath his nail, capturing bright blue blood beneath it. The doctor heated a paper clip and poked the nail with it to relieve pressure, causing the blue blood to turn bed immediately as a geyser of blood spurted upward from under the nail.

This is the same color shift that occurs in the capillaries surrounding the lungs' alveoli during the exchange of carbon dioxide and oxygen, and it is an image that I will never forget.

Blood changes colors depending on its oxygenation level. Oxygen-rich blood, such as that found in arteries, appears bright red due to the presence of oxygen-bound hemoglobin. Deoxygenated blood, like that found in veins, appears darker red or even bluish-red due to the reduced oxygen content. Additionally, blood can appear darker or brighter depending on factors such as the thickness of the skin and the depth at which the blood vessels are located.