Venous return mechanisms

• Return of blood to the heart

  The amount of blood the heart pumps is limited by venous return. Five mechanisms help to regulate it
• 1. Muscle pump


  Skeletal muscles contracting concentrically squeeze blood back to the heart quicker
• 2. Gravity


  Blood above the heart is aided in its return by gravity
• 3. Smooth muscle


  Can contract and relax smooth muscle to help push blood along the veins
• 4. Pocket valves


  One way valves prevent the 'backflow' of blood in the veins
• 5. Respiratory pump


  During inspiration blood is sucked back to the heart this is because high pressure in the abdomen and low pressure in the thoracic cavity