BRAINCAKEErythrocytes
Erythrocytes (red blood cells) are the most numerous cells in the blood, about 5 million per mm3. Their function is to transport oxygen from the lungs to the tissues, and they also help to carry carbon dioxide.
Erythrocytes are highly specialised for this role:
• Biconcave disc shape: this gives a large surface area to volume ratio for rapid diffusion of oxygen in and out, and no part of the cytoplasm is far from the surface.
• No nucleus: mature mammalian red cells lose their nucleus, leaving more space for haemoglobin. Each cell contains about 280 million haemoglobin molecules.
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Key terms in this lesson
- haemoglobin
- A globular, conjugated protein in red blood cells made of four polypeptide chains, each with a haem prosthetic group, that transports oxygen.
More in Circulatory Systems
- Double Circulation System
- Cardiovascular System
- Components of Blood
- Plasma
- Leucocytes
- Granulocytes
- Agranulocytes
- Platelets
All 33 lessons in Circulatory Systems · All Edexcel AS-level Biology topics