Arteries, veins and capillaries

• What should you be able to explain by the end of the video?

  Structure of arteries, veins, and capillaries
• What is the purpose of the double circulatory system in humans?

  To pump blood to lungs and body cells
• What do arteries carry from the heart?

  Very high pressure blood
• Why do arteries have thick muscular walls?

  To withstand very high pressure of blood
• What happens to blood in arteries with each heartbeat?

  It surges through the arteries
• What can be felt in the wrist as blood surges through arteries?

  Your pulse
• What role do elastic fibers play in arteries?

  They stretch and recoil to keep blood moving
• What do capillaries allow to diffuse from blood to cells?

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

  To allow rapid diffusion of substances
• What diffuses from cells back to the blood in capillaries?

  Carbon dioxide
• What happens to blood after it passes through the organs?

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

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

  Valves
• What is the function of valves in veins?

  To stop blood from flowing backwards
• What happens to valves when blood flows in the correct direction?

  They open to allow blood flow
• What happens to valves when blood starts to flow backwards?

  They shut to prevent backflow
• How do the structures of arteries, veins, and capillaries relate to their functions?

  • Arteries: Thick muscular walls withstand high pressure
  • Capillaries: Thin walls allow rapid diffusion
  • Veins: Thin walls and valves prevent backflow
• What are the main components of the human circulatory system?

  • Heart
  • Arteries
  • Veins
  • Capillaries