blood

• adaptations of capillaries:

  • thin = reduce diffusion distance
  • highly branched = large surface area for diffusion
  • narrow lumen = more diffusion
• collagen fibres in the heart prevent direct electrical flow from atria to ventricles
• movement of tissue fluid back into capillaries at the venule end is due to lower water potential in capillaries
• semi lunar valves location = between ventricles, pulmonary artery and aorta