The Blood Vessels

• Why is the human circulatory system a double circulatory system?

  blood passes through the heart twice for every circuit around the body – deoxygenated blood is pumped from the right side of the heart to the lungs, and the oxygenated blood that returns is pumped from the left side of the heart to the body
• How does the structure of an artery relate to its function?

  carries blood away from the heart under high pressure – has a small lumen and thick, elasticated walls that can stretch
• How does the structure of a vein relate to its function?

  carries blood back to the heart at low pressure –doesn’t need thick, elasticated walls, but has valves to prevent blood flowing the wrong way
• How does the structure of a capillary relate to its function?

  carries blood to cells and tissues – has a one-cell-thick wall to provide a short diffusion distance
• What is the function of the red blood cells?

  Bind to oxygen and transport it around the body
• What is the function of the white blood cells?

  Defend the body against pathogens
• What is the function of the plasma?

  Transports blood cells and substances around the body
• What are the three main types of blood vessels that blood flows around in the body?

  • Arteries
  • Veins
  • Capillaries
• Where do arteries carry blood?

  away from the heart
• What size lumen do arteries have?

  small lumen
• What type of walls do arteries have?

  thick walls containing muscle and elastic tissue
• Label the artery:

  A) small lumen

  B) thick wall

  C) thick layer of muscle and elastic fibres

  
• Where do Veins carry blood?

  toward the heart
• What size lumen do veins have?

  large lumen
• What type of walls do veins have?

  relatively thin walls
• Why do veins often have valves along their length?

  to prevent backflow of blood
• Label the vein:

  A) large lumen

  B) relatively thin wall

  C) often has valves

  
• What type of walls do capillaries have?

  narrow, thin-walled
• Where do the capillaries carry blood?

  through the organs
• What kind of lumen does a capillary have?

  narrow lumen
• What do capillaries do?

  allow the exchange of substances with all the living cells in the body
• Label the capillary:

  A) wall one cell thick

  B) tiny vessel with narrow lumen

  
• What are the blood vessels in humans and other mammals arranged into?

  a Double Circulatory System
• What do the Transport systems do in a double circulatory system? (2)

  • One transport system carries blood from your heart to your lungs and back again
  • The other transport system carries blood from your heart to all other organs of your body and back again.
• Label the Double Circulatory System:

  A) lungs

  B) pulmonary vein

  C) aorta

  D) head and body

  E) vena cava

  F) pulmonary artery