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Physical Education

The circulatory system

Blood vessels

There are three types of blood vessel:

Arteries

  • Carry blood away from the heart (always oxygenated apart from the pulmonary artery which goes to the lungs)
  • Have thick muscular walls
  • Have small passageways for blood (internal lumen)
  • Contain blood under high pressure

Veins

  • Carry blood to the heart (always de-oxygenated apart from the pulmonary vein which goes from the lungs to the heart)
  • Have thin walls
  • Have larger internal lumenlumen: The central cavity of a hollow structure in an organism or cell.
  • Contain blood under low pressure
  • Have valves to prevent blood flowing backwards

Capillaries

  • Found in the muscles and lungs
  • Microscopic – one cell thick
  • Very low blood pressure
  • Where gas exchange takes place. Oxygen passes through the capillary wall and into the tissues, carbon dioxide passes from the tissues into the blood

Back to Applied anatomy and physiology index

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