Arteries,veins and capillaries

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

  How the structure of arteries, veins, and capillaries relates to their function
• What type of circulatory system do humans have?

  A double circulatory system
• Where does blood collect oxygen in the circulatory process?

  In the lungs
• What happens to blood after it collects oxygen in the lungs?

  It returns to the heart and is pumped around the body
• What do arteries carry from the heart to the organs?

  Very high pressure blood
• What is the first adaptation of arteries that helps them function?

  They have very thick muscular walls
• Why do arteries need thick muscular walls?

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

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

  Your pulse
• What do elastic fibers in arteries do?

  They stretch and recoil to keep blood moving
• What are capillaries responsible for in the circulatory system?

  Allowing substances to diffuse between blood and cells
• What substances diffuse from the blood to the cells in capillaries?

  Glucose and oxygen
• What is the diffusion pathway like in capillaries?

  Very short due to their thin walls
• What happens to blood after it passes through the organs?

  It makes its way back to the heart through veins
• What is a problem with blood traveling back to the heart through veins?

  It travels slowly under low pressure
• Why do veins have thin walls?

  Because the blood pressure is low
• What do many veins contain to assist blood flow?

  Valves
• What is the function of valves in veins?

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

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

  They shut to prevent backflow
• What are the key structural differences between arteries, veins, and capillaries?

  • Arteries: Thick muscular walls, elastic fibers, carry high pressure blood
  • Veins: Thin walls, contain valves, carry low pressure blood
  • Capillaries: Very thin walls, allow for rapid diffusion of substances