B2- The circulatory system (blood vessels)

• What are the three 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
• What is the function of veins?

  To carry blood to the heart
• Why do arteries have thick walls?

  To withstand high pressure from the heart
• What is the lumen in blood vessels?

  The hole down the middle of the vessel
• What features make arteries strong and elastic?

  Thick muscle layers and elastic fibres
• How thick are capillary walls?

  One cell thick
• Why are capillaries important for diffusion?

  They have permeable walls for substance exchange
• What do capillaries supply to cells?

  Food and oxygen
• What do capillaries remove from cells?

  Waste like Carbon dioxide
• How do capillary walls affect diffusion rates?

  Thinner walls increase diffusion rates
• What happens to capillaries as they connect to veins?

  They join up to form veins
• Why are vein walls thinner than artery walls?

  Blood is at lower pressure in veins
• What is the lumen size comparison between veins and arteries?

  Veins have a larger lumen than arteries
• What do veins have to ensure blood flows correctly?

  Valves to keep blood flowing in one direction
• How do you calculate the rate of blood flow?

  Volume of blood ÷ number of minutes
• If 1464 ml of blood passes through an artery in 45 minutes, what is the rate of blood flow?

  $325 \text{ ml/min}$
• Why is it important to know the rate of blood flow?

  It helps assess circulatory system health