We are full of it, we need it, and we can't live without it.

So what exactly is blood and how much blood do I have?

Blood is the red-coloured fluid flowing continuously in our body. Approximately 1/12th of the body weight of a healthy human is blood. About 5 - 6 liters of blood is present in our body.

What are the main blood components?

Blood mainly consists of a fluid called plasma which includes suspended cellular particles; Red Blood Cells or RBC's, White Blood Cells or WBC's and tiny platelets.

What is the function of these components?

(a) Plasma acts as a vehicle that carries substances like enzymes, and hormones, glucose, fats, and proteins, etc., in addition to the blood cells. (b) Red Cells mainly carry oxygen from lungs to different body tissues; in turn, taking back carbon dioxide from the tissues to be thrown out of body. (c) White cells acts as body scavengers and guards. They help maintain the immune system function as the defense forces -killing the bacteria or any other foreign organism that enter the body. (d) What Platelets do is that they help in clotting and the coagulation process of blood.

The big question: How is blood formed?

As explained above blood consists of RBCs, WBCs, and platelets floating freely in the plasma. Early embryonic life- blood cells are formed in liver and spleen. By the fifth month- Haemopoisis (a fancy word for formation of blood) occurs in two locations: bone marrow & lymphatic tissues. At the birth of the child- the entire bone marrow is red and active. Gradually, with the growth of the child, the marrow remains red only in the flat bones and vertebrae. Every day new blood cells are produced in the bone marrow and old cells die. Red blood cells have a life of 120 days while white cells live for a few days and platelets only for a few hours.