What is a "red blood cell"?

A red blood cell, also known as an erythrocyte, is the most abundant type of blood cell in the human body. They are responsible for transporting oxygen from the lungs to various tissues and organs and carrying carbon dioxide, a waste product, back to the lungs for exhalation. Red blood cells are specialized cells that lack a nucleus and are packed with a protein called hemoglobin, which binds to oxygen molecules. Their unique biconcave shape increases their surface area, allowing for efficient gas exchange. Red blood cells play a crucial role in maintaining oxygenation and supporting the overall functioning of the body's systems.