Final answer:
Erythrocytes, or red blood cells, primarily transport oxygen to body tissues and carbon dioxide to the lungs, facilitated by the hemoglobin they contain.
Step-by-step explanation:
The main function of erythrocytes, commonly known as red blood cells (RBC), is to transport oxygen to tissues and remove carbon dioxide to the lungs. Red blood cells are equipped with hemoglobin, a metalloprotein that has the ability to bind up to four molecules of oxygen per molecule ensuring that a vast majority of oxygen that is transported through the blood is done so efficiently. This function is so critical that, without sufficient oxygen delivery to tissues, cells are unable to carry out their essential biochemical processes. The hemoglobin also transports a portion of carbon dioxide, a waste product, from the tissues back to the lungs, where it can be exhaled.