Blood Vessels

• The function of the Artery was to carry blood away from the heart to the body at high pressures
• The Artery:

  A) Small Lumen

  B) Thick and elastic muscle layer

  
• The function of the vein is to carry blood back to the heart from the body at low pressures.
• The Vein:

  A) Valves

  B) Large Lumen

  C) Thin muscle layer

  
• The function of the capillary is to allow the exchange of substances between the blood and the tissues
• The Capillary:

  A) Single Cell Wall

  B) Very small lumen

  
• The Double Circulatory System:

  A) Pulmonary Circulation

  B) Systemic Circulation

  C) Capillaries

  
• Why do the veins have a valves?

  To prevent backflow of oxygenated and deoxygenated blood
• Why do capillaries have no muscle layer?

  To make the walls permeable for diffusion
• Why are the arteries' muscle layer elastic and collagen fibres?

  To regulate the pressure of the blood by contracting and expanding