Help with Capillary Hydrostatic Pressure

[DrAK18]

Hi all,

I'm trying to figure out a question that I just can't seem to wrap my head around.

It essentially asks what has higher hydrostatic pressure, a single arteriole or a single capillary. I can't decide. On the one hand, the capillary bed has lower pressure as a whole thanks to the resistances adding in parallel. On the other hand, the question specifically states a single arteriole and a single capillary, which makes me think the capillary is the correct choice according to Poiseuille's Law (R = 8nl/πr^4)...a single capillary has a much smaller radius, which should increase the resistance and thus the pressure exponentially.

A little help here? Thanks much.

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[P0ke]

Hi all,

I'm trying to figure out a question that I just can't seem to wrap my head around.

It essentially asks what has higher hydrostatic pressure, a single arteriole or a single capillary. I can't decide. On the one hand, the capillary bed has lower pressure as a whole thanks to the resistances adding in parallel. On the other hand, the question specifically states a single arteriole and a single capillary, which makes me think the capillary is the correct choice according to Poiseuille's Law (R = 8nl/πr^4)...a single capillary has a much smaller radius, which should increase the resistance and thus the pressure exponentially.

A little help here? Thanks much.

I think the arteriole. I don't think its asking about an in-vitro experiment with a single capillary and a single arteriole isolated, but rather in the context of a living organism.

 

[CherryRedDracul]

Hi all,

I'm trying to figure out a question that I just can't seem to wrap my head around.

It essentially asks what has higher hydrostatic pressure, a single arteriole or a single capillary. I can't decide. On the one hand, the capillary bed has lower pressure as a whole thanks to the resistances adding in parallel. On the other hand, the question specifically states a single arteriole and a single capillary, which makes me think the capillary is the correct choice according to Poiseuille's Law (R = 8nl/πr^4)...a single capillary has a much smaller radius, which should increase the resistance and thus the pressure exponentially.

A little help here? Thanks much.

That's if you're assuming equal flow through both the capillary and the arteriole. Flow = pressure/resistance.

Don't overthink the question. What P0ke said is correct.