transport oxygen and carbon dioxide in the bloodstream
Red Blood Cells (RBCs), also known as erythrocytes, are the most common type of blood cell and are responsible for transporting oxygen from the lungs to the rest of the body and returning carbon dioxide back to the lungs for exhalation. They contain hemoglobin, a protein that binds to oxygen, and their biconcave shape increases the surface area for gas exchange, making them highly efficient at their job.