7.6 - Blood vessels an their functions

Cards (17)

  • What are the 4 blood vessels ?
    Arteries, veins, capillaries, arterioles
  • What do arterioles do ?
    Control blood flow from arteries to capillaries
  • What are the 5 layers that arteries, veins and arterioles have ?
    Tough fibrous layer, muscle, elastic layer, endothelium (inner lining), lumen
  • What’s the function of the tough fibrous outer layer ?
    Resist internal and external pressure changes
  • What’s the function of the muscle layer ?
    Constricts and dilates the vessel to control blood flow
  • What’s the function of the elastic layer ?
    Stretches and recoils to maintain blood pressure
  • What’s the function of the endothelium ?
    Smooth to reduce friction
  • What layers do capillaries have ?
    Endothelium and lumen
  • 4 ways in which artery structure is different to veins and how this helps with its function ?
    • Thicker muscle than veins - blood at higher pressure so can constrict and dilate to control volume of blood into arterioles
    • Thicker elastic layer than veins - stretch and recoils allows high pressure to be maintained
    • Thicker wall - ensures no bursting under high pressure
    • No valves - blood unlikely to back flow as at constant high pressure
  • 2 ways in which arterioles structure is different to arteries and how it helps with their function ?
    • Thicker muscle than arteries - allows lumen to constrict to restrict and control blood flow into capillaries
    • Thinner elastic layer than arteries - more area so at lower pressure, not a much stretch or recoils allows high needed
  • 4 ways in which vein structure is different to arteries and how this helps their function ?
    • Thinner muscle - blood not at high pressure, carry away from tissues
    • Thinner elastic - lower pressure, no need to stretch or recoil
    • Less thick walls - low pressure, allows flattening during skeletal contraction
    • Valves - low pressure so prevents backflow of blood
  • 4 ways in which capillaries structure aids their function ?
    • Walls are mostly endothelium - thin so shorter diffusion distance for rapid diffusion
    • Numerous and highly branched - provides a larger surface area for exchange
    • Narrow lumen - squeezes RBCs against walls, reducing diff distance
    • Spaces between endothelial cells - all WBCs to move out and fight infection in tissues and tissue fluid formation
  • What pressure does the pumping of the heart create?
    Hydrostatic pressure
  • What is tissue fluid formed by ?
    The ultrafiltration of blood plasma
  • Explain how tissue fluid is formed and returned back to the circulatory system
    • Ventricular systole means hydrostatic pressure is high at arterial end of capillaries
    • pressure causes small molecules (oxygen, water, ions, AA, glucose) to move out of blood plasma by ultrafiltration
    • hydrostatic pressure and water potential in the capillary is now lower than the tissue fluid outside
    • so water is forced back into capillary at venule end by the higher hydrostatic pressure also water leaves tissue fluid and enters blood via osmosis down a water potential gradient
  • How is excess tissue fluid returned to the circulatory system ?
    • carried back in the lymphatic system
    • Drains into blood via 2 ducts into veins close to the heart
  • In what 2 ways is the contents of the lymphatic system moved ?
    • Hydrostatic pressure of tissue fluid that left the capillaries
    • Contraction of body muscles squeeze lymph vessels