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GCSE Physical Education · key term
A tiny blood vessel with a wall one cell thick, where substances are exchanged between blood and surrounding tissues.
Used by AQA and OCR
Paper 1
A tiny blood vessel with a wall one cell thick, allowing substances to be exchanged between the blood and its surroundings.
Revise: Gaseous exchangeEach alveolus is surrounded by tiny blood vessels called capillaries.
A very small blood vessel linking the arterial and venous sides of circulation, where substances are exchanged between blood and surrounding tissues.
Paper 1
Revise: Cardiovascular System Structure and FunctionCapillaries are the smallest blood vessels. Their narrow passages allow red blood cells to squeeze through, and their walls are only one cell thick. This thin barrier allows substances such as oxygen and carbon dioxide to diffuse between blood and surrounding tissues.
When explaining an adaptation, link structure to function: for example, capillary walls are one cell thick, giving a short diffusion distance.
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