I think it's more that, following Bernoulli's equation for fluid flow in pipes, widening the artery while holding the flow rate constant means the velocity has to decrease. Maybe that means that the oxygen has more time to diffuse out before it reaches the point where it's supposed to, so that tissue doesn't get properly oxygenated?

[–] iocase@lemmy.zip 4 points 1 week ago* (last edited 1 week ago) (1 children)

A stroke is caused by one of two things:

A blood clot blocking an artery feeding part of your brain
A blood vessel rupturing (aneurysm rupture) that causes pressure to build inside or against your brain, squeezing blood vessels shut like a pressure bandage.

Both of them cause a lack of oxygenated blood to the brain, and treating one type makes the other worse.

As an aside: the city I used to live in had an ambulance with a CAT scanner in it that would be dispatched to suspected strokes. They could diagnose whether it was 1 or 2 and treat it right away.

As to why arterial widening causes lacunar strokes, the article didn't make it clear how or what small vessel disease is.

Gas exchange also doesn't happen in your arteries or veins, but in your capillaries. Your capillaries are small enough to just barely fit a single red blood cell (the RBC often need to bend to fit through) and that close contact of RBC and capillary wall allows fast and near complete gas exchange. The tightness of a capillary is a feature, not a bug. So it could be that you don't have consistent contact with the same RBC for long, and mostly are in contact with blood plasma?

[–] grue@lemmy.world 3 points 1 week ago

Gas exchange also doesn’t happen in your arteries or veins, but in your capillaries. Your capillaries are small enough to just barely fit a single red blood cell (the RBC often need to bend to fit through) and that close contact of RBC and capillary wall allows fast and near complete gas exchange. The tightness of a capillary is a feature, not a bug. So it could be that you don’t have consistent contact with the same RBC for long, and mostly are in contact with blood plasma?

Ah, so more or less the opposite of my guess. Man, I love Cunningham's Law!

[–] Gsus4@mander.xyz 2 points 1 week ago* (last edited 1 week ago)

I was expecting that for capillaries where red blood cells circulate almost in a conga line, not arteries.