Question 16

Compare the structure, function and coronary circulation of the right and left ventricles.

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College Answer

The question sought information on the structure (anatomy), function (physiology) and vascular supply of the right and left ventricle. Good answers provided detail in each section e.g. values for ventricular pressure rather than simply stating “high- and low-pressure systems”. Many marks may be gained by a simple anatomical description & labelled PV loop for each ventricle. Many candidates focussed solely on the coronary circulation, to which only a proportion of the marks were allocated

Discussion

An Anatomical Comparison of the Right and Left Ventricle
Domain Right ventricle Left ventricle
Shape Irregular; vaguely triangular Conical
Valves Tricuspid and pulmonic Mitral and aortic
Thickness Relatively thin: 2-5mm Three times thicker: 7-11mm
Mass ~ 26g ~90g
Position in the chest Right and anterior Left and posterior
Blood supply RCA and circumflex LAD and circumflex

From a functional point of view, the college asked to compare PV loops of the two ventricles, which might actually be insufficient (as it is hard to represent everything on the same diagram). Here is an optional diagram  which emphasises the differences of the RV:

right ventricular PV loop

And here is a table which offers a summary of the differences:

A Functional Comparison of the Right and Left Ventricle
Domain Right ventricle Left ventricle
End-diastolic volume Slightly higher than LV Slightly lower than RV
End-systolic volume Slightly higher than LV Slightly lower than RV
Stroke volume The same The same
Systolic pressure 25 mmHg 120 mmHg
Diastolic pressure 0 mmHg 3-8 mmHg
ESPVR (contractility) Lower Higher
EDPVR (elastance) Lower Higher
Ea (Afterload) Lower Higher
Stroke work (PV loop area) Lower Higher

References

Pasipoularides, Ares. "Right and left ventricular diastolic pressure–volume relations: a comprehensive review." Journal of cardiovascular translational research 6.2 (2013): 239-252.