Step I Cardiovascular Question

[Mushrooomboy]

Hello,

I understand that increasing venous resistance will increase systemic filtration, but I'm stuck on why decreasing arteriolar resistance will also increase filtration. Does anyone know?

 

[studentdocftw]

Think of filtration as a straight hose with holes in the middle of it...if you kink the end of the hose (increase venous resistance) more water will move through the holes in the middle. If you kink the front of the hose (increase arteriolar resistance), less water will reach the holes in the middle and less will filter. Thus, decreasing arteriolar resistance (let's say, straightening an already kinked hose) should increase filtration as water moves through the holes more easily. This is obviously an oversimplification, as oncotic pressure plays a role, but this is a way to think of the hydrostatic aspect. Decreasing arteriolar resistance will allow more filtrate to pass thru Bowman's space, increasing filtration.