Circulatory system-blood vessels

• What is the primary function of arteries in the circulatory system?


  Carry blood away from the heart
• What is the role of capillaries in the circulatory system?


  Exchange nutrients and oxygen with tissues
• What do veins do in the circulatory system?


  Carry blood back to the heart
• Why do arteries need to be strong and elastic?


  To withstand high pressures of blood inside
• What are the structural features of arteries?


  • Thick layer of muscle tissue
  • Thick layer of elastic tissue
  • Strong and elastic walls
• How do the walls of arteries compare to veins?


  Arteries have thicker walls than veins
• What are capillaries characterized by?


  Small vessels that come into contact with all cells
• What is the significance of capillary walls being thin and permeable?


  It allows substances to easily diffuse through
• What is the lumen of a capillary like?


  It is tiny
• Why do capillaries have lower blood pressure?


  It allows for slower flow, giving time for exchange
• What is the characteristic of veins regarding blood pressure?


  Veins operate at low pressure
• What are the structural features of veins?

  • Large lumen
  • Thin walls (small layer of elastic fibers and smooth muscle)
  • Have valves to prevent backflow
• How is the rate of blood flow calculated?


  Rate of blood flow = volume of blood / time taken
• Describe the flow of blood through the circulatory system.


  1. Heart
  2. Arteries
  3. Capillaries
  4. Veins
  5. Back to heart
• 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
• Why do arteries have thick muscle and elastic layers?


  Because blood pressure is high
• What is the main function of capillaries?


  To carry blood close to body cells for substance exchange
• What are the characteristics of capillary walls?


  They have thin, permeable walls
• Why are capillary walls thin and permeable?


  To allow substances to diffuse in and out easily
• What is the primary function of veins?


  To carry blood back to the heart
• What feature do veins have to prevent backflow of blood?


  Valves inside
• How do the walls of veins compare to those of arteries?


  Veins have thinner walls than arteries
• Why do veins have thinner walls than arteries?


  Because blood pressure is lower
• How is the rate of blood flow calculated?


  • Rate of blood flow = volume of blood / time taken
• What are the three different 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?


  To carry blood to the heart
• How does the heart affect blood pressure in arteries?


  The heart pumps blood out at high pressure to the arteries
• What are the characteristics of artery walls?


  Strong, elastic, and thick compared to the lumen
• Why do arteries contain thick layers of muscle?


  To make them strong and allow them to stretch
• What is the lumen in blood vessels?


  The hole down the middle of the blood vessel
• How thick are capillary walls?


  Only one cell thick
• What is the significance of capillaries being really small?


  They carry blood close to many cells for substance exchange
• What do the permeable walls of capillaries allow?


  Substances to diffuse in and out
• What substances do capillaries supply and remove?


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


  To increase the rate of diffusion by decreasing the distance
• How do veins form in the circulatory system?


  Capillaries eventually join up to form veins
• Why do veins have thinner walls than arteries?


  Because the blood is at lower pressure in the veins