Physiology Of The Heart

Front 1

Describe the events that occur during physiological systole

Back 1

• Mitral valve closes at the onset of systole
  
• A period of isovolumetric contraction occurs where ventricular pressure rises without any change in ventricular volume.
• Aortic valve opens once Ventricular pressure rises above aortic pressure
• blood ejection occurs until aortic valve closes due to aortic pressure exceeding ventricular pressure due to relaxation of the ventricle.

Front 2

Explain the pressure volume loop shown.

explain how to calculate SV and ejection fraction

Back 2

PV loop shows the ventricles relationship of pressure to volume.

• D correlates to the the closing of the MV and the end of diastole (First heart sound)
• Between d and C you can see isolvolumetric contraction before the aortic valve opens between C and A. Point C also depicts the end systolic volume and pressure. Aorta closes and you hear the second heart sound.
  
• the difference between the top of the curve and C = pulse pressure of ventricle
• stroke volume = the difference in volume between C and A
• The ejection fraction = stroke vol/ peak volume (D)

Front 3

Describe the shape and contraction of the left ventricle compared to the Right ventricle

Back 3

• Left ventricle has a shape like a cone and contracts with an apex to base squeezing motion. The LV muscle fibre orientation creates 3 separate motions during systole
  

- Inward/ radial

- longitudinal (base comes closer to apex)

- rotational motion (apex twist relative to the base)

• Right ventricle has a more complex shape, the infundibulum outflow tract wraps around the left ventricle anteriorly. Contraction is via a blow like motion contracting inwards towards the Ventricular septum
  

Front 4

Explian these terms:

1. Ejection fraction
2. Stroke volume
3. Cardiac output

Back 4

1. SV = the percentage change in the volume of the ventricle from EDV to ESV.

EF = SV/ EDV (Peak vol)

2. SV = Amount of blood ejected each beat = LVEDV - LVESV (peak volume - minimal volume)

3. CO = the amount of blood the heart pumps in one minute = SV x HR

Front 5

List the differences between the right ventricle and the left ventricle.

Back 5

Right ventricle has

• thinner walls
• one direction of contraction (compared to 3 for the LV)
• operates in a low pressure circuit
  
• Has a complicated shape with its outflow tract wrapping around the LV anteriorly.