blood vessels

• structure of artery?

  • thick muscular wall that withstands high blood pressure.
  • collagen coat (strength)
  • smooth muscle layer, contracts to control blood flow
  • elastic fibres, stretch and recoil to maintain blood pressure
  • smooth endothelium to reduce friction
  • narrow lumen
  • NO valves
• structure of vein?

  • smooth endothelium, reduces friction
  • wide lumen
  • valves, prevent backflow of blood
  • smooth muscle layer (thin) has less contraction ability
  • elastic fibres, has less elastic recoil
• structure of a capillary?

  • endothelium wall is 1 cell thick (short diffusion distance)
  • narrow lumen, slows blood flow + allows exchange time
  • pores on walls, allows passage of materials through wall into tissue fluid