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Atrial Pressure Changes During Cardiac Cycle

  • Atrial contraction → increase in atrial pressure ('a' wave).

  • As the atria begin to relax → there is small fall in pressure ('x' wave).

  • [1. (As the atrioventricular valves close → there is a small backflow of blood.) + 2. (Ventricles contract as close chambers → rise in ventricular pressure → some bulging of atrioventricular valve into the atria)] → Rise in atrial pressure ('c' wave).

  • Contraction of ventricular musculature along with contraction of papillary muscles of atrioventricular valve → pulls atrioventricular valve towards ventricles → fall in atrial pressure ('x1' wave).

  • Ongoing filling of atria during diastole → rise in pressure ('v' wave).

  • Opening of atrioventricular valve → rushing of blood from atria to ventricles → fall in pressure ('y' wave).

  • Next cycle begins with atrial contraction → increase in pressure ('a' wave) .


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