How does I.V. fluids get absorbed in to the body?

Intravenous. It means going right into a vein.

“The intravenous route is the fastest way to deliver medications and fluid replacement throughout the body, as they are introduced directly into the circulatory system and thus quickly distributed throughout the body.”
—Wikipedia

@Jeruba Your answer gives me more questions. Like what else can on inject into their body? Like sugar? Or caffeine? How does the iv. water go into the cells? Can one inject pureed veggies? Or will it kill you? How much liquid chocolate can one inject in one before one gets sick? Is it worse than heroin to inject an equal amount of fruit smoothy?

Blood volume needs to be big enough to keep us alive. Hydration is part of what keeps up our blood volume. Water also plays a part in balancing our electrolytes and many other things. Blood carries nutrients like vitamins and minerals and also oxygen, salts, clotting factors, all sorts of things throughout the body to keep us alive.

When you drink water, part of what happens is some of it is absorbed into the blood stream if it is needed. When you are dehydrated part of what is suffering is your blood needs more hydration too.

If you put the water right into the blood stream you skip a step, so it hydrates you faster. Especially when someone can’t swallow or digest fluids, IV fluids become essential.

If it’s more hydration than you need, the water is taken from the blood and flushed out through the kidneys. You can get too much hydration too fast, which can be deadly. Usually IV’s are a fairly slow drip.

You might want to watch this video on osmosis (it’s a little slow moving, but it talks about the importance of water and salt content and how some of our cells are selectively permeable and in this video discusses red blood cells).

https://m.youtube.com/watch?v=n3iNP_zwcWg

By the way when I watched it there was a short ad in the middle, but then the video starts again.

Look at the body as having 3 water compartments.
-Vascular (veinous) water compartment.
-Interstitial (lymph fluid) water compartment.
-Intercellular water compartment.
Water flows back and forth though the 3 compartments (like ocean tides) as needed by the body. As water from the digestive system or IV fluid is introduced into the veins the water flows as needed into the lymph and from the lymph into the cells.

As water is lost from the body the tide flows in the opposite direction.

To answer your follow ups, sugar and salt are carried in the blood stream to regulate different organ functions. So there are glucose and saline IV solutions.

But chocolate and liquified vegetables must be digested by the alimentary system to provide nutrients that are used and carried in the blood stream. The molecules are too complex and large to be processed without digestion.

IVs and injections into veins are the most efficient ways to deliver medications, no waste in the stomach. That’s why addicts inject drugs.

@RedDeerGuy1, do not inject anything into your veins. I hope you are kidding, but just in case—don’t.

Please do not inject Hershey’s Syrup into your veins!

@Darth_Algar Good idea.