blood vessels

• How does the structure of arteries relate to their function?

  thick, muscular walls to handle high pressure without tearing

  elastic tissue allows recoil to prevent pressure surges

  narrow lumen to maintain pressure
• How is the structure of veins related to their function?

  thin walls due to lower pressure

  has valves to ensure blood doesn't flow backwards

  have less muscular and elastic tissue as they don't have to control blood flow
• How is the structure of capillaries related to their function?

  walls are only one cell thick, providing short diffusion distance

  very narrow, so can permeate tissues and red blood cells can lie flat against the wall, effectively delivering oxygen to tissues

  numerous, and highly branched, providing a large surface area
• How is the structure of arterioles related to their function?

  branch off arteries and veins in order to feed blood into capillaries

  smaller than arteries and veins so that the change in pressure is more gradual as blood passes through increasingly small vessels
• How are venules structure related to their function?

  capillaries connect to venules

  have very thin walls that can contain some muscle cells

  venules join together to form veins
• Structure and function of veins?

  veins take blood back to the heart under low pressure

  they have a wider lumen than arteries

  they have very little elastic or muscle tissue

  veins contain valves to stop the blood flowing backwards

  blood flow through the veins is helped by contraction of the body muscles surrounding them
• What type of blood do veins carry?

  all veins carry deoxygenated blood, except for the pulmonary veins which carry oxygenated blood to the heart from the lungs
• Why do arterioles have a layer of smooth muscle?

  to allow them to expand or contract, thus controlling the volume of blood flowing into tissues