Red Blood Cell are red in colour due to the presence of a red pigment called haemoglobin inside them. Red Blood Cell (RBC) are carries of oxygen. Red blood cells carry oxygen from the lungs to all the cells or all the pats of the body which are connected to heart. It is actually the haemoglobin present red blood cells which carries oxygen in the body. Hemoglobin performs a very important function of carrying oxygen from lungs to body tissues. Haemoglobin also carries some of the carbon dioxide from body tissues to the lungs (most of carbon dioxide is carried by plasma of blood in the dissolved form). Red blood cells are circular in shape. Red blood cells do not have nuclei. Red blood cells have made very quickly upto only 1 days because they do not live for very long. Each red blood cells lives for about 4 months or 120 – 130 days only.
One reason for the short life of red blood cells is that they do not have nuclei. It has been estimated that about three million red blood cells of the human blood die everyday but four times that number are made in the bone marrow everyday. So, when we donate the blood to save the life of a other person, then the loss of blood from our body can be made up very quickly, within a day. This is because red blood cells are made very fast in only 1 second about 2 million red blood cells were formed in our bone marrow. please note that most of the cells in blood are red blood cells.