Blood

We have all seen blood. It is red in colour. We also know that blood is flowing in our body. Blood flows through the arteries, veins and capillaries in our body. Scientists and doctors agree that an average adult person has about three to four kilogrammes of blood in the body.

When we look at a drop of blood under a microscope we can see four things: (a) plasma, (b) white blood cells, (c) red blood corpuscles and (d) platelets.

Plasma is a thick yellowish liquid. It carries proteins. antibiotics, glucose, fats, mineral salts etc. to every part of the body. These are needed by the body for growth and repair and also to fight against germs and bacteria.

Red blood corpuscles are like tiny discs. They are about 0.008 millimetres in diameter. They carry oxygen from one part of the body to another. The corpuscles contain a substance called haemoglobin which makes the blood look red. There are, on the average, about 45 million red blood corpuscles in a woman's body and 55 million in a man's body.

White blood cells help to prevent disease by destroying invading bacteria, while platelets help in the clotting of blood when a part of the body is injured.