The function of red blood cells is to transport oxygen from the lungs to tissues throughout the body and to carry carbon dioxide back to the lungs for exhalation. These cells, also known as erythrocytes, contain hemoglobin, a protein that binds to oxygen molecules and facilitates their delivery to cells requiring oxygen for energy production. The biconcave shape of red blood cells increases their surface area, enhancing their ability to absorb and release gases efficiently. Maintaining healthy red blood cell levels is crucial for overall bodily function and proper oxygenation, supporting metabolic activities and cellular processes.