B4.1 - The Blood

Composition of the Blood

Blood transports materials and heat around the body, and helps to protect against disease. It contains:

• Plasma 
• Red blood cells 
• White blood cells 
• Platelets

Red blood cells

Red blood cells transport oxygen for aerobic respiration. They must be able to absorb oxygen in the lungs, pass through narrow blood vessels, and release oxygen to respiring cells.

Red blood cells have adaptations that make them suitable for this:

• they contain haemoglobin - a red protein that combines…