blood vessels

• what does an artery do

  carry blood away from the heart under the highest pressure
• what is the structure of an artery

  3 layers - tunica interma, tunica media, tunica external
• what is the outer layer of the artery made from

  collagen
• what is the middle layer of the artery made from

  smooth muscle
• how does the inner layer of the artery regulate blood pressure

  folds open/closed when blood is pumped
• what happens when the inner layer of the artery gets damaged

  body fills the hole with cholesterol

  cholesterol will bind to more cholesterol and form a plaque which when builds up can cause clotting
• when is blood clotting a problem

  in the brain - causes stroke

  in the heart - causes heart attack
• what are capillary walls made from

  squamous epithelial cells
• what do capillaries do

  carry blood at low pressure - one blood cell at a time
• how are veins structured

  large lumen

  less smooth muscle than arteries but more collagen
• how is blood moved

  skeletal contraction
• what prevents the backflow of blood

  valves
• what are the conditions under which blood is pumped away from the heart

  high pressure

  small amount
• what are the conditions under which blood is pumped towards the heart

  low pressure

  large volume