Heart structure

  • Created by: Mohsin
  • Created on: 11-04-18 15:53
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  • Heart structure
    • vascular physiology
      • Aorta
        • thick walls
          • receive nutrients and oxygen by diffusion
    • muscular artery
      • made up of collagenous connective tissue
        • strong and elastic - providing mechanical strength
    • arteriole
      • thick muscular walls
        • carry blood
    • Endothelial
      • produce a smooth surface
        • reduce surface friction
          • control contraction and status of the SM
      • provide an interrupted lining allowing small molecules to pass through diffusion
      • fenestrated capillaries (pores)
        • found in the glomeruli of the kidney
      • dis-countinous open pores
        • allow red and white blood cells to pass
          • present in the liver and spleen
      • endothelium governs blood-tissue exchange
    • Types of blood flow
      • Laminar = blood flows in a straight line through a long smooth vessel
      • Turbulent = rate of flow becomes too great, passes an obstruction, or passes over a rough surface
        • blood flows across swell as along forming currents
          • higher resistance
      • only two ways of altering flow
        • 1. Driving pressure must be changed
        • 2. Vascular resistance must be changed
    • venous return-valves
      • peripheral veins have one way valves
        • important to allow venous blood return to the heart
          • BP in the veins is low therefore challenge to return blood to the heart
    • capillaries
      • mean pressure, wall tension, radius and wall thickness is the lowest in the capillaries
        • wall stress is highest
    • vascular signalling
      • endothelium governs blood-tissue exchange
      • vascular tone
        • receptors to agonists such as Ach
          • endothelium responds to signals
            • secrete vasoactive ingredients (nitric oxide, prostacyclin)
              • act as vasodilators
              • low levels of nitric oxide may contribute to aretheroma formation


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