How does this work?
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You know that blood flows through arteries to capillaries. Capillaries are semi-permeable : they will let small things like water, oxygen, CO2, nutrients through but no proteins or red blood cells (normally). This filtered fluid bathes the cells of organs, muscles, skin etc and keeps our cells hydrated and gives the gas/nutrients to the cells.
Blood doesn’t need to reach everywhere. They can just dump the stuff cells cells need into the surrounding tissues and they’ll get the stuff to where it needs to go.
Microscopically speaking youd be surprised at how many capilaries there are -drunk histo tech
No cell is further than one cell removed from a capillary so they’re all pretty close. But the material transport mechanism is diffusion. And there’s fluid surrounding capillaries and cells that acts as a transport medium.
Movement and massage are good for you partly because they increase the movement of this fluid which increases rate of diffusion.
That’s also why you feel stiff and icky in the morning. Your cells are relatively deprived of nutrients / filled with waste.
Blood doesn’t need to reach every cell in the body.
The vessels are just the roads to get you near where you need to be with important substances in them. The blood can introduce whatever material to a certain area and each of those areas may have its own mechanism of delivering those substances where they need to go.
As cars on the road trying to arrive at a destination- some need to take a bridge still,some a ferry, some air transported, some need a RFID to get thru certain gates, some can only fit on certain roads etc. Same with blood and their mechanisms to deliver important cells and whatnot.
Can someone actually explain this like I’m 5? I’m not smart enough for this…
Nah you’re right there aren’t. It’d probably be possible for a organism to engineer some blood vessels made out of cells without nuclei like that one fly that’s smaller then most amoeba and transport oxygen through blood plasma but that’s unnecessary for the same reason why insects can get away with having a full-body lung instead of blood; oxygen diffuses between cells so blood vessels only need to reach *groups* of cells rather then each and every cell individually.
This is also why acupuncture needles don’t normally make you bleed; they’re thin enough to slip between individual blood vessels. It’s just bad luck that one in every five or so hit a blood vessel head-on and make you bleed. It’s also why mosquitos need to be able to detect heat to find blood vessels; if they didn’t then they’d miss four times out of five.
As other people have said, charged concentrations will attempt to balance themselves out passively, and can also be forcibly reversed using an active transport system (think powered toll booths) located on the surfaces of all cells. There are also physical connective junctions between cells, which all substances to pass from cell to cell that are too large to be transported through the cell membrane otherwise. In other words, the equivalent of tunnels. Between these two mechanisms (and a couple of others for larger molecules and biochemical products), almost any substance, be it an ion, atom, or chemical construct, can move between cells without effort.
However, it also needs to be noted, that many of these system either require energy input to work, ionic gradients to work, or transport molecules. In the case of oxygen transport, for example, a major player is what is the enzyme known as cytochrome C oxidase. If this enzyme is inhibited, cells – and thus organisms – can actually die no mater how effectively they can take in oxygen via physical respiration. The reason cyanide is a poison that kills so effectively is that it actually binds to cytochrome C oxidase, and permanently deactivates it. If enough of it’s cytochrome C oxidase is deactivated, a cell cannot complete the steps needed to create energy using oxygen, and a lack of energy will kill any and all cells in minutes.
An ELI5: you know how in movies set in old times when there’s a fire and people form a line to pass buckets? Cells pretty much do that.
Imagine a bunch of people stood in line, and they were thirsty. The person near the well takes a glass and drinks, then they fill up a glass and passes it to the person next to them and they drink, and so on until the last person in line has had their glass of water.
Other people have gone in better detail, but the bottom line is cells help each other!
This is a really good question! It’s all about distance. A capillary only needs to get close enough for the various things like oxygen or sugar to drift across the gap. So yeah basically every cell in your body is within a millimeter or so of a capillary. There’s a few notable exceptions like your eyeball but mostly it’s just proximity. I think a good analogy is roads. Is there a road to your bed ? No. There’s a road to your driveway though. Is there a road to your office desk? Almost . The last few feet you walk to your work or home is the diffusion part.
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