Generally, there is 3 to 4 litres of blood in the body of normal person. The blood circulates in the arteries, veins and capillaries. We all know that the colour of blood is red in men, women and all over the world.
Do you know why the blood is red in colour?
To give the answer of this question, first we have to know about the composition of blood. There are four main constituents in our blood. These are white blood corpuscles, red blood corpuscles, plasma and platelets. More than half of the human blood consists of plasma. It is yellow coloured thick fluid, which contains carbohydrates, fats, proteins, salts, fibrinogens, antibodies etc. Proteins help the body to grow, antibodies help to kill the harmful bacteria and neutralize the toxins secreted by them. The bleeding from the cuts can be stopped with the help of fibrinogen. The size of white blood corpuscles about .01 mm and they are less in number. For every 700 red blood corpuscles, there is only one white blood corpuscle. They fight against the germs of diseases and protect our body from them. Platelets are also very small in size-about 0.002 mm. There are about 150,000 to 400,000 platelets in one cubic millimeter of blood. These platelets are helpful in the clotting of blood. Red blood corpuscles are saucer shaped and they have size about .008 mm. They give colour to the blood. These cells carry oxygen from one part to another in the body. They contain a red coloured pigment known as ‘hemoglobin’. Because of this pigment the color of the blood is red. Hemoglobin is made up of proteins and iron. In a healthy woman each cubic millimeter of blood have about 4.5 million red blood corpuscles, whereas in man, one cubic millimetre blood has 5.5 million red blood corpuscles. Shortage of these cells causes anemia. As soon as the blood passes through the lungs, these particles absorb oxygen and then carry it to various parts of the body. Every red blood corpuscle breaks up after four months in the spleen. The worn out cells are replaced by the new red cells which are always being formed.