A red blood cell (erythrocyte) is the most abundant blood cell and is responsible for transporting oxygen from the lungs to the body’s tissues and carrying carbon dioxide back to the lungs.
Red blood cells contain hemoglobin, an iron-rich protein that binds oxygen. Their distinctive biconcave disc shape increases surface area for gas exchange and allows them to pass through very small blood vessels.
Unlike most cells, mature human red blood cells do not have a nucleus, leaving more space for hemoglobin.
QUICK FACT
- Red blood cells circulate through blood vessels for approximately 120 days before being removed and recycled primarily by the spleen and liver.
- An average adult has about 20–30 trillion red blood cells circulating at any given time.
COMMONLY CONFUSED WITH
- Hemoglobin: the oxygen-carrying protein inside red blood cells.
- White blood cell: immune cell involved in defense and inflammation.
- Platelet: cell fragment involved in blood clotting.
SEE ALSO
