Please tell me if this is a boring topic, maybe but somehow I don't feel bored.
Perhaps in an effort to be objective, the "why" got left out. It may be obvious to some but not me.
Do jugulars collapse because they are floppy and lay flat? In that very-low-pressure environment, that would happen slowly, if the veins were floppy. Just a gradual shift, on account of the very light wall weight, and the relative absence of gravity's pressure keeping them 'patent'. Kind of like a liquid, spreading out flat on the floor when there's no container any more?
At that time, since gravity is less of an influence, we would have to rely on other pressure to get the fluid down. The vertebral veins are more narrow. So is there more pressure on them, to get similarly large volumes of blood through the narrower channel in the same time? Is any of it negative pressure?
Seems like a gizmo like IVUS would be useful, a tiny strain guage measuring very very localized pressure, with ones for arteries and ones for veins. And while we're at it, a very very small Doppler probe. IVDUS.
What am I driving at? I am trying to understand flow changes. Plus I am still interested in the lying-down change, because I wake up feeling worse than when I went to bed, and as soon as I sit up, better. And I am also intrigued by the 3D vein images with ballooned veins above the stenosis. Age and gravity may cause loose vessels, when they are under pressure, to change shape over time. But these really look blown up like a balloon.
I am getting something wrong? Yes; NORMAL is for the jugulars to be OPEN when you are lying down, and SHUT when you are standing up. When you are lying down, MORE bloodflow goes through the jugulars, (LESS through the spinal column path?). I can't understand that. If the path is more open, there should be less velocity, too. I wake up feeling like my brain has been shut down for 7 hours, not asleep. If you'll accept Bill Gates' terms (asleep and shut down -- does it have to do with oxygen?).
Why are these vessels used more when we lie down? We lie flat, they inflate. Counter-intuitive to me. The flow would slow. That
's when they should collapse, when less gravitational pressure is forcing liquid through them, and more pulling the top wall down toward the bottom. Is it because the vessel just works that way, and top and bottom attachments assure that? Is it maybe because we are lying down on the other path? Or because it changes somehow, pinching off the vertebral path? What happens when the poor sod has problems in both? Aaack. Evolution seems to have me extremely baffled.
Maybe there's a function being done while we lie down that's more important, and requires more flow in a certain area? Like unconscious vigilance to predators?
What's supposed to inflate my jugulars when I lie down? Even if it isn't doing that in my case. Why is what's supposed to be normal, normal at all?
Please do not bother with this if it is too scattered. Loss of cogneetoes does that to me sometimes. I know this must be second-nature to someone looking at them through fluoroscopes. Also if it will all be clearer after I read the paperback version.