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The Steps of The Cardiac Cycle

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Presentation on theme: "The Steps of The Cardiac Cycle"— Presentation transcript:

1 The Steps of The Cardiac Cycle
“The Rhythm is gonna get you”

2 Atrial Systole Lasts 0.1 sec Atria contract, and the ventricles relax
SA node depolarizes This causes a P wave on an EKG Forces blood through the open AV valves into the ventricles Creates Systole Atrial Systole contributes to the final forced push of about 25 mL of blood into the ventricles from the atria

3

4 Ventricular Systole Ventricles depolarize and the atria relax
Lasts seconds At the beginning of this phase the pressure rises in the ventricle chambers and it pushes blood against the AV valves forcing them shut Myocardium begins to contract but does not exert force right away As the ventricles begin to contract, pressure rises since the valves are closed off

5 Ventricular Systole Cont
Once left ventricular pressure rises above about 80 mmHg and right ventricular pressure rises above 20 mmHg, both semilunar valves open and blood is ejected Pressure continues to rise in the left ventricle to about 120 mmHg Rises to about mmHg in the right ventricle At the end of this phase the T wave of the EKG marks the point of ventricular repolarization This is the point where they cannot contract

6

7 Relaxation Period Lasts about 0.2-0.4 seconds
Marks the time when the atria and ventricles both relax SL valves close off since blood begins to flow back due to the lack of pressure from the ventricles As soon as the ventricular pressure falls below the atrial pressure the AV valves open up and the filling process begins over again At the end of the relaxation period the ventricles are about ¾ full and the next cycle begins One cycle lasts 0.8 sec in an average heart

8 Process Diagrams Step-by-Step
Cardiac Cycle Process Diagrams Step-by-Step Copyright © 2007 by John Wiley & Sons, Inc.

9 R T (a) ECG P 1 Atrial depolarization 1 Q S 0.1 sec 0.3 sec 0.4 sec Atrial systole Ventricular systole Relaxation period 120 100 Dicrotic wave Aortic pressure 80 (b) Pressure (mmHg) Left ventricular pressure 60 40 Left atrial pressure 20 (c) Heart sounds S1 S2 S3 S4 130 (d) Volume in ventricle (mL) 60 (e) Phases of the cardiac cycle Atrial contraction Isovolumetric contraction Ventricular ejection Isovolumetric relaxation Ventricular filling Atrial contraction

10 R T (a) ECG P 1 Atrial depolarization 1 Q S 0.1 sec 0.3 sec 0.4 sec 2 Begin atrial systole Atrial systole Ventricular systole Relaxation period 120 100 Dicrotic wave Aortic pressure 80 (b) Pressure (mmHg) Left ventricular pressure 60 40 Left atrial pressure 20 2 (c) Heart sounds S1 S2 S3 S4 130 (d) Volume in ventricle (mL) 60 (e) Phases of the cardiac cycle Atrial contraction Isovolumetric contraction Ventricular ejection Isovolumetric relaxation Ventricular filling Atrial contraction

11 R T (a) ECG P 1 Atrial depolarization 1 Q S 0.1 sec Begin atrial systole 0.3 sec 0.4 sec 2 Atrial systole Ventricular systole Relaxation period 3 End (ventricular) diastolic volume 120 100 Dicrotic wave Aortic pressure 80 (b) Pressure (mmHg) Left ventricular pressure 60 40 Left atrial pressure 20 2 (c) Heart sounds S1 S2 S3 S4 3 End (ventricular) diastolic volume 130 (d) Volume in ventricle (mL) 60 (e) Phases of the cardiac cycle Atrial contraction Isovolumetric contraction Ventricular ejection Isovolumetric relaxation Ventricular filling Atrial contraction

12 R T (a) ECG P 1 Atrial depolarization Q 4 S 0.1 sec Begin atrial systole 0.3 sec 0.4 sec 2 Atrial systole Ventricular systole Relaxation period 3 End (ventricular) diastolic volume 120 Ventricular depolarization 100 Dicrotic wave 4 Aortic pressure 80 (b) Pressure (mmHg) Left ventricular pressure 60 40 Left atrial pressure 20 (c) Heart sounds S1 S2 S3 S4 End (ventricular) diastolic volume 130 (d) Volume in ventricle (mL) 60 (e) Phases of the cardiac cycle Atrial contraction Isovolumetric contraction Ventricular ejection Isovolumetric relaxation Ventricular filling Atrial contraction

13 R T (a) ECG P 1 Atrial depolarization Q 4 S 0.1 sec 2 Begin atrial systole 0.3 sec 0.4 sec Atrial systole Ventricular systole Relaxation period 3 End (ventricular) diastolic volume 120 Dicrotic wave 4 Ventricular depolarization 100 Aortic pressure 5 80 5 Isovolumetric contraction (b) Pressure (mmHg) Left ventricular pressure 60 40 Left atrial pressure 20 (c) Heart sounds S1 S2 S3 S4 End (ventricular) diastolic volume 130 (d) Volume in ventricle (mL) 60 (e) Phases of the cardiac cycle Atrial contraction Isovolumetric contraction Ventricular ejection Isovolumetric relaxation Ventricular filling Atrial contraction

14 R T (a) ECG P 1 Atrial depolarization Q 4 S 0.1 sec 0.3 sec 0.4 sec 2 Begin atrial systole Atrial systole Ventricular systole Relaxation period 3 End (ventricular) diastolic volume 120 Ventricular depolarization 100 Dicrotic wave 4 Aortic pressure 5 80 5 Isovolumetric contraction 6 (b) Pressure (mmHg) Left ventricular pressure 60 40 6 Begin ventricular ejection Left atrial pressure 20 (c) Heart sounds S1 S2 S3 S4 End (ventricular) diastolic volume 130 (d) Volume in ventricle (mL) 60 (e) Phases of the cardiac cycle Atrial contraction Isovolumetric contraction Ventricular ejection Isovolumetric relaxation Ventricular filling Atrial contraction

15 R T (a) ECG P 1 Atrial depolarization Q 4 S 0.1 sec 2 Begin atrial systole 0.3 sec 0.4 sec Atrial systole Ventricular systole Relaxation period 3 End (ventricular) diastolic volume 120 4 Ventricular depolarization 100 Dicrotic wave Aortic pressure 5 80 5 Isovolumetric contraction 6 (b) Pressure (mmHg) Left ventricular pressure 60 40 6 Begin ventricular ejection Left atrial pressure 20 7 End (ventricular) systolic volume (c) Heart sounds S1 S2 S3 S4 End (ventricular) diastolic volume 130 Stroke volume (d) Volume in ventricle (mL) 60 7 (e) Phases of the cardiac cycle Atrial contraction Isovolumetric contraction Ventricular ejection Isovolumetric relaxation Ventricular filling Atrial contraction

16 R T (a) ECG P Q 8 1 Atrial depolarization S 0.1 sec Begin atrial systole 0.3 sec 0.4 sec 2 Atrial systole Ventricular systole Relaxation period 3 End (ventricular) diastolic volume 120 Ventricular depolarization 100 Dicrotic wave 4 Aortic pressure 80 5 Isovolumetric contraction (b) Pressure (mmHg) Left ventricular pressure 60 40 6 Begin ventricular ejection Left atrial pressure 20 7 End (ventricular) systolic volume 8 Begin ventricular repolarization (c) Heart sounds S1 S2 S3 S4 End (ventricular) diastolic volume 130 Stroke volume (d) Volume in ventricle (mL) 60 (e) Phases of the cardiac cycle Atrial contraction Isovolumetric contraction Ventricular ejection Isovolumetric relaxation Ventricular filling Atrial contraction

17 R T (a) ECG P 1 Atrial depolarization Q 8 S 0.1 sec Begin atrial systole 0.3 sec 0.4 sec 2 Atrial systole Ventricular systole Relaxation period 3 End (ventricular) diastolic volume 120 9 Ventricular depolarization 100 Dicrotic wave 4 Aortic pressure 80 5 Isovolumetric contraction (b) Pressure (mmHg) Left ventricular pressure 60 6 Begin ventricular ejection 40 Left atrial pressure 20 7 End (ventricular) systolic volume 8 Begin ventricular repolarization (c) Heart sounds S1 S2 S3 S4 9 Isovolumetric relaxation End (ventricular) diastolic volume 130 Stroke volume (d) Volume in ventricle (mL) 60 (e) Phases of the cardiac cycle Atrial contraction Isovolumetric contraction Ventricular ejection Isovolumetric relaxation Ventricular filling Atrial contraction

18 R T (a) ECG P 8 1 Atrial depolarization Q S 0.1 sec 0.3 sec 0.4 sec 2 Begin atrial systole Atrial systole Ventricular systole Relaxation period 3 End (ventricular) diastolic volume 120 9 Ventricular depolarization 100 Dicrotic wave 4 Aortic pressure 80 5 Isovolumetric contraction (b) Pressure (mmHg) Left ventricular pressure 60 Begin ventricular ejection 40 6 Left atrial pressure 20 10 7 End (ventricular) systolic volume 8 Begin ventricular repolarization (c) Heart sounds S1 S2 S3 S4 9 Isovolumetric relaxation End (ventricular) diastolic volume 130 10 Ventricular filling Stroke volume (d) Volume in ventricle (mL) 60 (e) Phases of the cardiac cycle Atrial contraction Isovolumetric contraction Ventricular ejection Isovolumetric relaxation Ventricular filling Atrial contraction

19 R T (a) ECG P 1 Atrial depolarization 1 Q S 0.1 sec 0.3 sec 0.4 sec Atrial systole Ventricular systole Relaxation period 120 100 Dicrotic wave Aortic pressure 80 (b) Pressure (mmHg) Left ventricular pressure 60 40 Left atrial pressure 20 (c) Heart sounds S1 S2 S3 S4 130 (d) Volume in ventricle (mL) 60 (e) Phases of the cardiac cycle Atrial contraction Isovolumetric contraction Ventricular ejection Isovolumetric relaxation Ventricular filling Atrial contraction

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