NEET MDS

The Power Course

Work done by left ventricle is more than the right ventricle because of



Choices

1 ) Wall is thicker
2 ) Stroke volume is greater
3 ) Contraction is slower
4 ) Afterload is more
5 ) Preload is more

Explanation


Work-done by heart

Work done by any pump is calculated by  W = PΔV.  Where P is Pressure generated and ΔV is change in volume. The heart is also a pump so pressure here is intraventricular pressure generated and Volume change is the amount of blood ejected i.e stroke volume

Preload

Amount of distention before contracting i.e before systole. This is measured by end-diastolic volume. As per the Frank-Starling equation, within the limits force of contraction increases with distention. Cardiac preload is not much different, between left and right ventricle in physiological conditions. So, this not the reason for the difference in work done

Afterload

This is the amount of pressure generated during contraction i.e. systolic pressure. systolic pressure in the left ventricle is normally around 120mmhg and right ventricle is around 25mmhg So this is the main reason for different work done between  left and right ventricle

Stroke volume

This is the amount of blood ejected by one ventricle in single systole.  There is no difference between left and right ventricular stroke volume in "physiological conditions". There may be a difference in pathological conditions like MR AR TR PR and shunts.

 

 

 


Answer

Afterload is more

Last Modified : 25-Dec-2019

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