Events Of The Cardiac Cycle

Front 1

Describe the events of the cardiac cycle, including ventricular, arterial and atrial pressures, volumes and sounds, as a function of time.

Back 1

7 phases

Front 2

Draw PV loops to represent the events of the cardiac cycle

Back 2

picture

Front 3

Describe the basic concepts underlying tissue elasticity and the Law of Laplace, and how they apply to ventricular contraction

Back 3

Elasticity refers to stiffness. It is proportional to pressure difference divided by volume difference. thus, the more pressure the vessel exerts for each unit increase in its volume, the greater its elastance.

Law of Laplace:
Stress = Pressure x radius / 2h

This law may apply to ventricular contraction. The stress that a heart chamber must develop to discharge the amount of blood inside is proportional the pressure that is required to eject it and the radius of the heart (that approximates a sphere). Furthermore, it is inversely proportional the thickness of the wall (thus, the heart can decrease the stress by increasing the thickness of its wall.

The law of LaPlace can be extended to wall vessels by the following equation:
stress = P(transmural) x radius/h