Arteries veins and capilaries

• What type of circulatory system do humans have?

  Double circulatory system
• What is the primary function of arteries?

  Carry high-pressure blood from the heart
• What do arteries have that allows them to withstand high pressure?

  Very thick muscular walls
• How do elastic fibers in arteries function?

  They stretch and recoil to maintain blood flow
• What can be felt in the wrist as blood surges through arteries?

  Your pulse
• What happens to blood when it reaches the organs?

  It flows through capillaries
• What substances diffuse from blood to cells in capillaries?

  Glucose and oxygen
• Why do capillaries have very thin walls?

  To allow rapid diffusion of substances
• What happens to blood after it passes through the organs?

  It returns to the heart via veins
• Why do veins have thin walls?

  Because the blood pressure is low
• What do many veins contain to prevent backflow of blood?

  Valves
• How do valves in veins function?

  They open to allow forward flow and close to prevent backflow
• How do the structures of arteries, veins, and capillaries relate to their functions?

  • Arteries: Thick muscular walls for high pressure
  • Veins: Thin walls and valves for low pressure
  • Capillaries: Thin walls for rapid diffusion
• Where can you find questions on arteries, veins, and capillaries?

  In the revision workbook