From the Research
A single red blood cell (RBC) contains approximately 270 million hemoglobin (Hb) molecules. This high concentration of hemoglobin is what gives red blood cells their primary function of oxygen transport throughout the body. Each hemoglobin molecule can carry up to four oxygen molecules, which means a single RBC can transport over a billion oxygen molecules at once. The abundance of hemoglobin in RBCs is necessary because oxygen has limited solubility in blood plasma alone. Hemoglobin's structure, with its four protein subunits each containing a heme group with an iron atom at its center, allows it to bind oxygen in the lungs where oxygen concentration is high and release it in tissues where oxygen concentration is lower. This remarkable concentration of hemoglobin molecules explains why RBCs appear red and why they are so efficient at their specialized role of oxygen delivery throughout the body. Some key points to consider:
- The number of hemoglobin molecules in a red blood cell is crucial for its function in oxygen transport 1.
- Each hemoglobin molecule can carry up to four oxygen molecules, allowing a single RBC to transport a large number of oxygen molecules at once.
- The structure of hemoglobin, with its four protein subunits and iron atom at the center, enables it to bind and release oxygen as needed.
- The high concentration of hemoglobin in RBCs is necessary due to the limited solubility of oxygen in blood plasma alone.
- The recycling of hemoglobin from senescent red cells is an important source of iron flux in the body, with roughly 2 million senescent red cells being recycled each second 1.