What is the primary function of red blood cells?

The primary function of red blood cells (RBCs) is to transport oxygen from the lungs to tissues and carry carbon dioxide back to the lungs for exhalation. RBCs contain haemoglobin, a protein that binds to oxygen, giving them their red colour. These cells are produced in the bone marrow and have a lifespan of about 120 days. Their biconcave shape increases surface area, allowing efficient gas exchange. A healthy red blood cell count is crucial for oxygen delivery and overall energy levels. Anaemia, a condition caused by low RBC levels, can lead to fatigue and other health issues.