Cvs module phase II MBBS 2007- 2008 CARDIAC CYCLE PHYSIOLOGY CARDIOVASCULAR MODULE PHASE II...
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Transcript of Cvs module phase II MBBS 2007- 2008 CARDIAC CYCLE PHYSIOLOGY CARDIOVASCULAR MODULE PHASE II...
cvs module phase II MBBS 2007-2008
CARDIAC CYCLE
PHYSIOLOGY
CARDIOVASCULAR MODULE
PHASE II 2007-2008
cvs module phase II MBBS 2007-2008
INSTRUCTOR INFORMATIONDr AZRA KIRMANIASSISTANT PROFESSORDEPARTMENT OF PHYSIOLOGYROOM NO 951/1FIRST FLOOR BUILDING 9EXT- 24306MOBIL- 0501639346, RESIDENCE - 6022433
cvs module phase II MBBS 2007-2008
Events of the cardiac cycle at a heart rate of 75 beats/min
Ventricular Diastole 0.5 seconds
Ventricular Systole 0.3 seconds
Atrial systole 0.1 secondAtrial Systole 0.7 seconds
cvs module phase II MBBS 2007-2008
• Atrial systole contributes 30% 0f ventricular filling.
• The end diastolic ventricular volume is 130ml.
cvs module phase II MBBS 2007-2008
REDUCED EJECTION
Late in systole, the aortic pressure actually exceeds the ventricular, but for a short period momentum keeps the blood moving forward.
cvs module phase II MBBS 2007-2008
PROTODIASTOLE
• Once the ventricular muscle is fully contracted, the already falling ventricular pressures drop more rapidly. This is the period of protodiastole. It lasts about 0.04 s. It ends when the momentum of the ejected blood is overcome and the aortic and pulmonary valves close, setting up transient vibrations in the blood and blood vessel walls.
cvs module phase II MBBS 2007-2008
• The amount of blood ejected by each ventricle per stroke at rest is 70-90 mL.
• The end-diastolic ventricular volume is about 130 mL.
• Thus, about 50 mL of blood remains in each ventricle at the end of systole (end-systolic ventricular volume).
• The ejection fraction, the percent of the end-diastolic ventricular volume that is ejected with each stroke, is about 65%.
• The ejection fraction is a valuable index of ventricular function.
cvs module phase II MBBS 2007-2008
Events of the cardiac cycle at a heart rate of 75 beats/min
• 1, atrial systole;
• 2, isovolumetric ventricular contraction;
• 3, ventricular ejection; – Rapid ejection– Slow ejection– Protodiastole
• 4, isovolumetric ventricular relaxation;
• 5, ventricular filling.
cvs module phase II MBBS 2007-2008
Note that late in systole, aortic pressure actually exceeds leftventricular pressure. However, the momentum of the blood keeps it flowing out
of the ventricle for a short period.