Blood vessels pack 3 part 2

• What is the primary function of blood vessels in the circulatory system?

  To transport blood throughout the body
• What are the three main types of blood vessels and their functions?

  • Arteries: Carry blood away from the heart
  • Capillaries: Exchange substances between blood and tissues
  • Veins: Return blood to the heart
• What do arteries do?

  They carry blood away from the heart.
• How do arteries carry blood?

  Under high pressure from the heart's pumping action.
• What structural features of arteries allow them to carry blood under pressure?

  Thick walls and elastic fibers.
• What is the thickness of artery walls compared to their lumen?

  The walls are thick compared to the size of the lumen.
• Why do arteries contain thick layers of muscle?


  To make them strong and elastic.
• How thick is the wall of a capillary?

  Only one cell thick.
• What do capillaries branch from?

  Arteries.
• Why are capillaries described as being really tiny?

  Because they can only be seen with a microscope.
• What is the function of capillary walls being only one cell thick?

  To facilitate diffusion of substances.
• What do veins do?

  They carry blood back to the heart.
• Why do veins have thinner walls compared to arteries?

  Because the blood is at lower pressure in veins.
• What structural feature helps veins accommodate blood flow despite lower pressure?

  Bigger lumen than arteries.
• What is the purpose of valves in veins?

  To help keep the blood flowing in the right direction.
• What is an interesting fact about the length of blood vessels in the human body?

  • The body contains about 60,000 miles of blood vessels.
  • This is approximately six times the distance from London to Sydney.
• How do capillaries supply food and oxygen to cells?

  By allowing diffusion through their thin walls.
• What is the advantage of capillary walls being only one cell thick?

  It increases the efficiency of diffusion.