They take oxygen from lungs and gills and spread them in blood capillaries. The cytoplasm of these cells is rich in hemoglobin which is an iron containing bio molecule able to bind oxygen. This hemoglobin is responsible to make these cells of red color. More specifically, the hemi iron ions in the hemoglobin produce red color.

In human bodies, the mature red blood cells are biconcave disks which are flexible. They lack in cell nucleus and organelles.

 

 

Erythrocyte consists of mainly hemoglobin and a typical human erythrocyte is of about 6 to 8 micrometer in diameter and 2 meter in thickness. They look like a disc. Adult human beings produce around 30 trillion red blood cells at any time. People have around 4 to 6 million of erythrocytes per cubic meter. People, who live in high altitude areas where oxygen tension is lacking, can have more erythrocytes.

Red blood cells in human bodies are more than any other cells and approximately, they are quarter of the cells present in human body.

 

 

There are many blood diseases which are involved because of red blood cells as well. Some of those diseases are, anemia, hemolysis, polycythemias and hemolytic transfusion reactions.

Human red blood cells have a life cycle; they produced from a process which is usually known as erythropoietisis, they develop from committing stem cells to mature red blood cells. When they get mature, they lie in body for 100 to 120 days and after that, they are removed through circulation. There is a lot more about red blood cells and if you are interested to know more about it, you can always check videos on internet to find how exciting our red blood cells are.