Blood vessels and thier functions

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Four different types of blood vessels:

  • Arteries - Carry blood away from heart and into the arterioles
  • Arterioles - Smaller arteries that control blood flow from arteries to capillaries
  • Capillaries - Tiny vessels that link arterioles to veins
  • Veins - Carry blood from the capillaries back to the heart

Arteries,arterioles and veins have the same basic structure. From the outside in they have:

  • Tough outer layer = resists pressure changes
  • Muscle layer = contracts and relaxes to control flow of blood
  • Elastic layer = Helps to maintain blood pressure by streching and pinging back
  • Thin inner lining (endotherlium) = Smooth so prevents friction and thin to allow diffusion
  • Lumen = Central cavity of the blood vessel  through which the blood flows
  • 

Arteries - strcuture and function

TRANSPORT BLOOD RAPIDLY UNDER HIGH PRESSURE FROM HEART TO TISSUES

  • Thick muscle layer compared to veins = smaller arteries can constrict and dialate to control the volume of blood passing through
  • Elastic layer is thin comapred to veins = Becuase blood pressure in the arteries needs to be kept high to reach everywhere in the body
  • Thick wall = Makes sure the vessel doesn't burst under pressure

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