Blood Vessels

• What do arteries carry blood away from?

  The heart
• What is the function of the endothelium in arteries?

  It reduces friction
• What role do elastic fibres play in arteries?

  They enable stretch and recoil
• How do smooth muscle and elastic tissue in arteries help maintain pressure?

  They prevent bursting and maintain pressure
• What is the function of collagen in arteries?

  It provides strength
• How do arterioles differ from arteries in terms of their structure?

  Arterioles have a narrower lumen
• What is the primary function of veins?

  To carry blood to the heart
• How do veins facilitate blood flow despite lower pressure?

  They contain valves to stop backflow
• How do the structures of veins and venules differ?

  Venules are smaller and have thinner walls
• What role do skeletal muscles play in blood flow in larger veins?

  They help push blood along towards the heart
• How do breathing movements assist in blood flow to the heart?

  They create pressure changes that move blood back
• What is the thickness of capillary walls?

  One cell thick
• What allows fluids to move out of capillaries?

  Gaps between epithelial cells
• Why is a large number of capillaries beneficial for diffusion?

  They provide a large surface area
• How does the lumen size of capillaries affect blood flow?

  It is smaller than arterioles, slowing blood flow
• What is the effect of the total cross-sectional area of capillaries on blood flow?

  It slows the flow down to allow more diffusion
• What are the main structural differences between arteries and veins?

  • Arteries have a narrow lumen; veins have a large lumen
  • Arteries have thicker walls; veins have thinner walls
  • Arteries contain more elastic tissue; veins have less
  • Veins contain valves; arteries do not