VR graph

[MissMedicine]

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on the VR graph, can someone explain to me why VR increases as EDV/R atrial P decreases... BRS phys doesnt explain and stupid me, who never really understood cardio phys cant figure it out.

can someone help?

 

[AlexRusso]

when there is less pressure in the right atrium it is "easier" for blood from the venous system to flow in there and hence the venous return goes up. Blood flow is driven by pressure differences. The flow into the RA from the veins is dependent upon the pressure difference between the two (Press in veins - Press in RA) If you decrease the RA press you increase this difference i.e. if the RA press is 0 then the diff is equal to the press in the veins. Conversly, if you increase the RA pressure you decrease the gradient and thus less venous return.

 

[Gauss]

There are only 2 things you need to know about physio:
1. things go from high pressure to low pressure until equal
2. things go from high concentration to low concentration until equal

you can derive almost everything from that

The purpose of life is to prevent reaching equilibrium

 

[MissMedicine]

when there is less pressure in the right atrium it is "easier" for blood from the venous system to flow in there and hence the venous return goes up. Blood flow is driven by pressure differences. The flow into the RA from the veins is dependent upon the pressure difference between the two (Press in veins - Press in RA) If you decrease the RA press you increase this difference i.e. if the RA press is 0 then the diff is equal to the press in the veins. Conversly, if you increase the RA pressure you decrease the gradient and thus less venous return.

makes sense.... THANKS Alex!