Question about ventricular compliance

[echox184]

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Hello,

Was hoping someone could explain this to me. Why when there is decreased compliance (increased stiffness), does ventricular pressure go up? I feel like if the ventricular walls are stiff and there is reduced EDV (less blood going into the ventricle, and less pressure when it contracts to push it out) the pressure would overall decrease since the volume going into the ventricle is smaller, and the ability for it to contract is also reduced so wouldn't the pressure go down? Am i thinking about this the wrong way?

 

[FMDoge2020]

It is more like when you increase transmural pressure by vasoconstriction, the compliance goes down. You can also think of compliance as the ability for the vein to store blood(capacitance).
when there's a decrease in venous compliance, less "blood pool" can be reserve in the vein(not stretchy anymore), allowing the blood to return to the heart. So your EDV increase due to increase of venous return. And this can be a consequence of sympathetic stimulation.

Main point:
1)when you vasoconstricts, pressure goes up not down
2)most blood at normal resting condition is stored in the vein
3)the body decrease compliance of vein to facilitate venous return.(so a increase, not decrease in EDV)
4)the total pressure is mainly regulated by the artery and arterioles, not vein

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