The Blood

• Features of capillaries


  • Suitable for gas exchange
  • Found in organs
• Capillary beds


  A network of capillaries found in organs
• Blood spends most time in capillaries


  As this is the site of exchange of nutrients and wastes
• Tissue fluid


  The fluid that surrounds body cells, transporting substances between the blood and the cells
• Haemoglobin


  The protein in red blood cells that binds to oxygen
• Blood vessels


  • Arteries
  • Veins
  • Capillaries
• Red blood cells


  • Lack a nucleus to make room for more haemoglobin
  • Biconcave shape gives greater surface area for gas exchange
• What is this diagram showing?

  Tissue Fluid

  
• What are the properties of veins?

  Low pressure, thin walls, carry deoxygenated blood back to the heart.
• What are the properties of arteries?

  Thick, elastic, muscular.
• What are the properties of capillaries?

  Thin walls, small diameter, site of gas exchange, connect arterioles and venules.