According to the Merck Manual Home Health Handbook, the primary function of erythrocytes, more commonly known as red blood cells, is to transport oxygen from the lungs to the body's many tissues. Red blood cells are also responsible for retrieving carbon dioxide from tissues and transporting it back to the lungs where it can be exhaled.
The Merck Manual Home Health Handbook states that the characteristic bright red color of blood is a by-product of the protein hemoglobin, which is found within all red blood cells. Hemoglobin binds to individual oxygen molecules, allowing red blood cells to carry them throughout the cardiovascular system.
The University of Rochester Medical Center describes red blood cells as round, slightly flat, disk-like cells with an indented center. Red blood cells are produced in bone marrow, which is found within certain types of bone. Individual red blood cells live for about 120 days.
The Merck Manual Home Health Handbook reports that red blood cells are the most prolific solid component found in blood and account for roughly 40 percent of its volume. The other solids found in blood are white blood cells and platelets. The solid components of blood are suspended in a fluid called plasma, which makes up more than half of blood's volume.