BRAINCAKERed Blood Cells
Red blood cells (erythrocytes) transport oxygen from the lungs to respiring tissues. They are the most numerous cells in the blood and are highly specialised for this job.
Adaptations:
• Biconcave disc shape: this gives a large surface area to volume ratio, so oxygen diffuses in and out quickly.
• Small size (about 7-8 µm in diameter): every haemoglobin molecule is close to the cell surface, so the diffusion distance is short. The cells fit through capillaries in single file, bringing them close to tissue cells.
• No nucleus (in mammals), and no mitochondria or endoplasmic reticulum: this leaves more space for haemoglobin, so each cell carries more oxygen. Without mitochondria, the cell does not use the oxygen it carries.
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Key terms in this lesson
- haemoglobin
- The iron-containing, globular protein in red blood cells that binds reversibly to oxygen for transport around the body.
More in Transport in Animals
- Heart Sounds
- Basic Rhythm of the Heart
- Electrocardiograms
- Aortic Aneurysms
- Haemoglobin
- Oxygen Loading and Unloading
- The Oxygen Dissociation Curve
- Partial Pressure of Oxygen
All 32 lessons in Transport in Animals · All OCR AS-level Biology topics