The Blood Vessels

• What are the three main types of blood vessels?

  Arteries, capillaries, and veins
• What is the primary function of arteries?

  To carry blood away from the heart
• What role do capillaries play in the circulatory system?

  They are involved in the exchange of materials at the tissues
• What is the function of veins in the circulatory system?

  To carry blood back to the heart
• How do arteries handle the blood pumped from the heart?

  They carry blood under high pressure
• What features of artery walls contribute to their function?

  They are strong, elastic, and have thick layers of muscle
• What do arteries branch into?

  Arterioles
• What are capillaries described as?

  Really tiny and too small to see
• What are networks of capillaries in tissue called?

  Capillary beds
• How do capillaries facilitate the exchange of substances?

  They carry blood really close to every cell and have permeable walls
• What substances do capillaries supply and remove?

  They supply food and oxygen, and take away wastes like CO₂
• Why are capillary walls usually only one cell thick?

  To increase the rate of diffusion by decreasing the distance
• What do capillaries branch into?

  Venules
• How do venules relate to veins?

  Venules eventually join up to form veins
• Why do veins have thinner walls compared to arteries?

  Because the blood is at lower pressure in the veins
• What is the lumen of veins compared to arteries?

  Veins have a larger lumen than arteries
• What feature do veins have to help blood flow in the right direction?

  Valves
• What is an interesting fact about the total length of blood vessels in the human body?

  • The body contains about 60,000 miles of blood vessels.
  • This is about ten times the distance from London to Sydney.
  • Capillaries are tiny and can only be seen with a microscope.
• What is the purpose of the extra page in the study material?

  To provide more information about the circulatory system
• How do the structures of arteries, capillaries, and veins relate to their functions?

  Arteries have thick, elastic walls for high pressure; capillaries are thin for diffusion; veins have valves and larger lumens for low pressure.