EVERYDAY SCIENCE

Detailed explanation-1: -It is a common myth that veins are blue because they carry deoxygenated blood. Blood in the human body is red regardless of how oxygen-rich it is, but the shade of red may vary. The level or amount of oxygen in the blood determines the hue of red. As blood leaves the heart and is oxygen-rich, it is bright red.

Detailed explanation-2: -Furthermore, the blood in human veins is also not blue. Blood is always red. Blood that has been oxygenated (mostly flowing through the arteries) is bright red and blood that has lost its oxygen (mostly flowing through the veins) is dark red.

Detailed explanation-3: -Human blood is red because hemoglobin, which is carried in the blood and functions to transport oxygen, is iron-rich and red in color. Octopuses and horseshoe crabs have blue blood. This is because the protein transporting oxygen in their blood, hemocyanin, is actually blue.

Detailed explanation-4: -What color is blood? There’s no need to build up the suspense: Blood is red. It might vary from a bright cherry red to a dark brick red, but it’s always red.

Detailed explanation-5: -The external structures of the heart include the ventricles, atria, arteries and veins. Arteries carry blood away from the heart while veins carry blood into the heart. The vessels colored blue indicate the transport of blood with relatively low content of oxygen and high content of carbon dioxide.