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The cardiac cycle
 

The cardiac cycle

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    The cardiac cycle The cardiac cycle Presentation Transcript

    • The Cardiac Cycle Charlotte Richardson
    • The cardiac cycleThis presentation goes through the stages of the cardiac cycle that occur in one full contraction of the heart.
    • The cardiac cycleThere are four stages of the cardiac cycle: I. Isovolumetric contraction II. Ventricular ejection III. Isovolumetric relaxation IV. Ventricular filling
    • The cardiac cycleBroadly the stages of the cardiac cycle can be divided into systole and diastole: I. Isovolumetric contraction Systole- when the ventricles II. Ventricular ejection are contracting III. Isovolumetric relaxation Diastole- when the IV. Ventricular filling ventricles are relaxingHere the cycle has been depicted as starting from the end of diastole when the ventricles are relaxed and filled with blood
    • Phase 1: Isovolumetric ContractionThe left ventricle isfull of blood andbegins to contract.This causes thepressure in the left Aortic pressureventricle to increase. PRESSURE (mmHg) Left atrial pressure Left ventricular pressure Left ventricular IV I II III IV pressure PHASE OF THE CARDIAC CYCLE
    • Phase 1: Isovolumetric ContractionOnce the pressure inthe left ventricleexceeds that of theleft atrium the mitralvalve will close. Aortic pressureThis is to prevent PRESSURE (mmHg)blood from goingback into the leftatrium. Mitral valve closes Left atrial pressure Left ventricular pressure Left ventricular IV I II III IV pressure PHASE OF THE CARDIAC CYCLE
    • Phase 1: Isovolumetric ContractionThe ventriclescontinue tocontract, but until theaortic valve opens thepressure in the leftventricle increases Aortic pressurewith no change in PRESSURE (mmHg)volume- this isisovolumetriccontraction. Isovolumetric contraction Left atrial pressure Left ventricular pressure Left ventricular IV I II III IV pressure PHASE OF THE CARDIAC CYCLE
    • Phase 2: Ventricular ejectionOnce the pressure inthe left ventricleexceeds that of theaorta the aortic valvewill open. PRESSURE (mmHg) Aortic pressure Aortic valve opens Left atrial pressure Left ventricular pressure Left ventricular IV I II III IV pressure PHASE OF THE CARDIAC CYCLE
    • Phase 2: Ventricular ejectionBlood then leavesthe left ventricle into Ventricular ejectionthe systemiccirculation via theaorta- ventricularejection Aortic pressure PRESSURE (mmHg) Left atrial pressure Left ventricular pressure Left ventricular IV I II III IV pressure PHASE OF THE CARDIAC CYCLE
    • Phase 3: Isovolumetric relaxationThe ventricles nowbegin to relax once Aortic valve closesthe blood has beenejected.When the pressure Aortic pressurein the left ventricle PRESSURE (mmHg)falls below that ofthe aorta the aorticvalve will close. Thisprevents bloodflowing back into theleft ventricle from Left atrial pressurethe aorta. Left ventricular pressure Left ventricular IV I II III IV pressure PHASE OF THE CARDIAC CYCLE
    • Phase 3: Isovolumetric relaxationAs the ventriclesrelax the pressurewill fall, but therewill be no change involume until themitral valve opens- Aortic pressurethis is isovolumetric PRESSURE (mmHg)relaxation Isovolumeteric relaxation Left atrial pressure Left ventricular pressure Left ventricular IV I II III IV pressure PHASE OF THE CARDIAC CYCLE
    • Phase 4: Ventricular fillingOnce the pressure inthe left ventricle fallsbelow that in the leftatrium the mitralvalve will open. Aortic pressureThis then allows the PRESSURE (mmHg)ventricles to fill withblood from the leftatrium, preparingthe ventricles for Mitral valve opensanother round of thecardiac cycle. Left atrial pressure Left ventricular pressure Left ventricular IV I II III IV pressure PHASE OF THE CARDIAC CYCLE
    • The cardiac cycle- recapPhases of the cardiac cycle: I. Isovolumetric contraction Systole II. Ventricular ejection III. Isovolumetric relaxation Diastole IV. Ventricular filling
    • The cardiac cycle- recap Ventricular ejection Aortic valve closes PRESSURE (mmHg) Aortic pressure Aortic valve opens IsovolumetericIsovolumetric relaxationcontraction Mitral valve opens Mitral valve closes Left atrial pressure Left ventricular pressure IV I II III IV PHASE OF THE CARDIAC CYCLE