Difference Between Red & White Blood Cells

Two of the main components of human blood are red blood cells and white blood cells. While both types of blood cells are produced in similar ways, they have very different functions in the body. Without both red and white blood cells, bodily functions that are essential to good health would not be possible.

A doctor holding a test tube with blood inside. (Image: psphotograph/iStock/Getty Images)

Origins

Both red and white blood cells are produced in the same way. Ninety-five percent of all blood cells are produced in the bone marrow, which is the soft, sponge-like material in the center of the bone. Other blood cells are produced in the liver, spleen and lymph nodes. All blood cells start out as stem cells. The stem cell then matures and evolves to become a red blood cell, white blood cell or platelet.

Function of Red Blood Cells

Red blood cells help blood to perform its most important function. Red blood cells travel through the bloodstream to transport oxygen from the lungs to the other parts of the body and carry carbon dioxide back to the lungs. The gases are transported by a protein within the red blood cell known as hemoglobin. Hemoglobin makes up 95 percent of the volume of a red blood cell and, when oxygenated, gives the red blood cells their signature red color.

Function of White Blood Cells

White blood cells are the disease-fighting cells of the human body. These cells fight harmful bacteria, viruses and fungi and help to remove them from the body. White blood cells produce antibodies, which can overpower a germ. They also can work by surrounding and devouring harmful bacteria. White blood cells also serve an important role in removing dead and dying red blood cells from the body, as well as devouring foreign substances such as dust and asbestos.

Lifespan

Red and white blood cells live within the body for different lengths of time. All blood cells eventually outlive their useful lifespan and die. The average life span for a red blood cell is 120 days. White blood cells have a much shorter life span, living on average from a few days to a few weeks. As these cells die, they are constantly being replaced by new blood cells produced within the bone marrow.

Number

A healthy bloodstream contains more red blood cells than white blood cells. In a healthy body, red blood cells typically make up between 40 and 50 percent of the overall blood volume. White blood cells generally compose about 1 percent of the blood volume. The amount of each type of blood cell present in the blood can vary based on certain medical conditions. People who suffer from anemia typically have fewer red blood cells. People fighting an infection are likely to have more white blood cells.