Why is blood red?
Becasue one of the most important ingredients of blood is haemoglobin, the molecule which carries blood around, which is held in the red blood cells. At the core of haemoglobin is an atom of iron which can exist either in an oxidised state, with an atom of oxygen attached to it, when it is red, or in a non-oxydised state, when it is blue. Normal function is for the heamoglobin to be pumped to the lungs, where it it picks up oxygen, then pumped round the body to where the oxygen is needed. When the oxygen is taken away, for example to power a muscle, heamoglobin is routed back via the veins (which appear blue) to the lungs again. Of course, if you cut yourself, even venous blood is instantly oxygenated by contact with the air, so blood outside the body always appears red.
So it is easier to spot. The blood flowing through the arteries, capillaries, and veins of our bodies contains many different materials and cells, each with a different function. Plasma, the liquid portion of the blood, comprises more than half of the blood. Plasma is light yellow in color, and is thicker than water, because it contains many substances, in addition to the actual blood cells. These substances include proteins, antibodies that combat disease, fibrinogen, which helps blood clot, carbohydrates, fats, salts, and others. Red blood cells, or corpuscles, encased in blood vessels, color the blood. Since there are about 35 trillion of these tiny, round, flat discs circulating in one’s body at any one time, their sheer number necessarily lends their red color to the blood. As the young red blood cell matures, and takes on an adult form in the marrow of the bone, it loses it’s nucleus, and it increases its production of hemoglobin. Hemoglobin is the red pigment, or color of blood,
