HEART

• right side pumps deoxygenated blood to lungs
• left side pumps oxygenated blood to rest of body
• Cardiac Cycle


  1. Atrial Systole

  2. Ventricle Systole

  3. Diastole
• Atrial Systole


  • Ventricles relax, atria contract
  • Decreases vol of chambers in atria which inc pressure
  • This inc in pressure forces AV valves open and pushes blood into ventricles
• Ventricle Systole


  • Decreases vol and inc pressure in ventricles
  • Causes AV valve to close
  • In turn this forces SL Valve open and forces blood into arteries
• Diastole


  • Both atria and ventricles relax so pressure is reduced in both chambers
  • Higher pressure in aorta closes SL valve
  • Blood returns to heart and atria fill again due to higher pressure in vena cava
  • Inc in pressure in atria due to blood causes AV valve to open again
• cords= prevent valves opening the wrong way
• why is there a short delay before avn wave?

  allow atria to fill before ventricles contract
• valves= prevent back flow of blood]
• HEART ADAPTIONS

  • L ventricle thicker & more muscular than right as needs to contract w/ more force to pump blood around whole body
  • Ventricles thicker walls than atria as have to push blood out of heart
• PATH OF BLOOD FLOW

  1. pulmonary vein
  2. L. atrium
  3. L. AV valve
  4. L. ventricle
  5. L. SV Valve
  6. Aorta