The primary role of red blood cells (RBCs), or erythrocytes, is to transport oxygen from the lungs to the body’s tissues and to carry carbon dioxide from the tissues back to the lungs for exhalation. These cells contain hemoglobin, a specialized protein that binds to oxygen, allowing efficient gas exchange. The ability of red blood cells to deform easily helps them navigate through capillaries, optimizing oxygen delivery. An adequate number of healthy red blood cells is crucial for maintaining energy levels and overall health, as they play a vital role in cellular respiration.