The card does need some working, but the adjustment leaves it a bit open-ended. Oncotic pressure by far not the only pressure that moves fluid into or out of the blood vessel. The suggestion’s phrasing leaves no way to discern which of a few pressures you’re talking about
{{c1::Oncotic pressure::… pressure}} exclusively moves fluid {{c2::into::into or out of}} the blood vessel. maybe?
Is it exclusive in that? I don’t know that it is, tbh
For sure oncotic and osmotic are not interchangeable terms, so the card does need to be clarified, though
It’s actually a little tricky. It’s a frame of reference problem. By definition, oncotic pressure always refers to a pull into a substance. Here’s the starling equation:
• The term (\pi_c - \pi_i**)** shows oncotic forces as a net effect.
• If \pi_c dominates, net movement is into the capillary.
• If \pi_i dominates, net movement is out of the capillary.
The actual mechanism never changes—oncotic pressure always pulls, but whether it pulls into or out of the capillary depends on which pressure is stronger .
Yes but is it exclusive in doing that? As in, are there not multiple possible answer for what pressure/s could move fluid into a vessel? Rendering the card a bit moot
‘X pressure moves fluid into the vessel’ isn’t a viable card, tbh
I’m not aware of any other type of pressure for the MCAT that also exclusively moves fluid into the blood vessel. Hydrostatic pressure exclusively pushes fluid out of a vessel with respect to intracapillary hydrostatic pressure. Osmotic pressure can do either.
There are for sure multiple other pressures that move fluid into a vessel.
Hydrostatic does not exclusively move out, either. In most cases, that is the case but that is not a hard rule and there are exceptions (your favorite, the kidney)
I can think of at least three cases that render the suggestion’s phrasing moot
There are other named pressures that exclusively move fluid into the vessel? I agree there are other pressures that move fluid into a vessel but are there any other named pressures that they definitionally refer to a pull inward of fluid?
Indeed there are, young jedi. 
The easiest example is just hydrostatic; it pushes either way depending (in the glomerulus it pushes both in and out)
Osmotic pressure, obviously, goes in and out.
Interstitial hydrostatic pressure pushes only in.
Etc., etc.
There may be others that escape my immediate memory/attention, but for sure enough that the existing phrasing needs some love
Ohhhh I see what you’re saying. I agree this is what I was saying above oncotic pressure definitionally requires a frame of reference because it is a subset of osmotic pressure that is always defined relative to a specific compartment (typically the blood vessel). Similarly hydrostatic pressure is defined relative to a specific compartment.
Definitionally,
Oncotic pressure is an osmotic pull inward with respect to your reference fluid/compartment.
Hydrostatic pressure is pushing force outward with respect to your reference fluid/compartment.
However, as shown by Starling’s equation:
If interstitial oncotic pressure \pi_i becomes greater than capillary oncotic pressure pi_c , it will pull fluid out of the capillaries and into the interstitial space. However that doesnt change the fact that capillary oncotic pressure exclusively refers to a pull inward its just exceeded by the interstitial oncotic pressure.
similarly, exactly what you’re describing in the kidneys:
Hydrostatic pressure in the glomerulus is higher than in Bowman’s space and this difference pushes fluid into Bowman’s space. However that doesnt change the fact that the hydrostatic pressure within Bowmans space exclusively exerts a push outward its just exceeded by the hydrostatic pressure of the glomerulus.
Maybe we can make this more clear with something like this maybe? kinda ugly you’re normally better with wording these things:
Oncotic pressure exerts an osmotic pull into the reference compartment, that may be exceeded if an opposing oncotic force in another compartment is stronger.
Kind of a tough concept to word in a short sentence.
It is tough to capture fully. I suspect that’s (at least part of) why the card hasn’t seen many changes
The trick, as usual, is to find a way to snake towards an improvement without wholesale reinventing the wheel