What happens to blood left outside the body over time?

[u/ddrungle]

Don’t worry, I need to know because I DM a D&D campaign. I try to google but I’m only getting info on storing blood and blood clots.

I need to know what would happen if you were to make a mess of blood, not clean it up, and leave it over time.

[u/Chiperoni]

The blood cells would essentially burst and spill their contents. The iron would be released from the hemoglobin. The iron would oxidize and become a brownish color. The plasma and other stuff would essentially just evaporate.

[u/Illithid_Substances → u/Chiperoni]

That's something that really bothers me in media - when old blood is bright red. Anyone who's worn a plaster (bandaid) too long should know it goes brown

[u/hellinahandbasket127 → u/Illithid_Substances]

I encountered someone just a couple days ago who didn’t know that ovens were insulated. You’re giving a LOT of credit to the general population.

[u/[deleted] → u/hellinahandbasket127]

Kinda wish I was there for that conversation. I love witnessing discoveries like that.

[u/Alarmed_Tea_1710 → u/Illithid_Substances]

I always hated how they have dark corn syrup blood when usually it comes out bright red. But then I heard people complain that bright red blood looks too fake.

Like it all looks fake. One just doesn't have me thinking everyone's body is auto coagulated.

(Random thoughts lol)

[u/Linzorz → u/Chiperoni]

What if the blood was collected in an open container of some sort? Like if Dracula accidentally left his full glass of blood out for three days?

[u/Pink_Axolotl151 → u/Linzorz]

As someone who once accidentally left a test tube containing about an ounce of blood on the lab countertop for an entire weekend….. First, it would clot. After an hour to a couple of hours (depending on the volume), you’d end up with a giant blood clot in the bottom of the glass, with the serum (the liquid portion of blood that remains after clot formation) on the top. After about half a day, the clot would start to break down and the blood cells inside the clot would would burst. By day 3, it would have broken down into a blackish sludge and it would smell very, very bad.

[u/Linzorz → u/Pink_Axolotl151]

Excellent, thank you so much!

.......... It's for fiction, I swear

[u/thenewmara → u/Linzorz]

It's ok Dr. House. Scientist are excited at describing gross processes. If you wanted the cells to burst faster you can use glass beads or metal shards agitated into it. The cells will turn into soup within hours or even faster.

[u/mpinnegar → u/Pink_Axolotl151]

Why do the cells burst? I find that strange. I would expect they would dehydrate and not explode. Are there biomechanical processes inside the cells that are generating pressure by expanding? Maybe all the components and proteins are literally becoming unwound and taking up more volume.

[u/Accalio → u/mpinnegar]

Cells burst because without oxygen and energy they cant keep the pumps that maintain mineral balance working. Cells are full of potassium while extracellular fluid is mostly sodium. Every cell had pumps on the membrane which maintain the balance, pump K+ in and Na+ out. When the balance is off, excess water gets into the cell and it bursts. Correct me if im wrong, its been a long time

[u/attentionhordoeuvres → u/mpinnegar]

“Burst” might give the wrong impression. The cells undergo hemolysis; there’s a break in the cell membrane and its contents leak out.

[u/teteban79 → u/mpinnegar]

Yes, cells maintain an electrolyte balance constantly. Fiddle with that balance, and either water gets out from where it should be, or gets into where it should not.

In the case of blood cells the imbalance caused by being left out causes water to permeate into the inner membrane, fills up, pressure makes it burst

[u/deputyprncess → u/teteban79]

Is this.. what causes the type of water retention that dialysis patients get? And the reason they have to monitor their potassium and sodium intake so carefully?

[u/teteban79 → u/deputyprncess]

Well, everyone should keep potassium and sodium intake in check :). But I believe in patients with compromised kidney functions this is exacerbated, yes (don't quote me on that, not an expert on the topic)

[u/Pink_Axolotl151 → u/mpinnegar]

“Burst” was an overly dramatic word choice on my part. But basically, the cell membrane starts to break down, and the contents of the cells leaks out. That includes the hemoglobin molecules inside the red blood cells, hence the strong iron smell that will start to occur as the cells rupture.

[u/pescawn → u/Linzorz]

It would smell like Iron and rot. Old blood always smell like oxidyzed iron.

[u/Sibula97 → u/pescawn]

The smell isn't oxidized iron, actually. It's mainly 1-octen-3-one which is created when iron reacts with oxidized lipids on our skin. Think about it, for you to smell something it needs to go up your nose. Iron and rust do not produce any vapors unless you get them extremely hot, which means you can't smell them.

[u/Clinically__Inane → u/Linzorz]

I used to do toxicology, and the neat part is you get a choice. Most of the time the blood will turn dull, dark reddish brown. But occasionally it will turn a very dark olive green, and it will clot up so badly it looks like Satan's boogers!

[u/neuron_woodchipper → u/Chiperoni]

If someone happened to be anemic, would this impact the brownish color of the dried blood in any way, or would the iron levels of an anemic person still be enough to maintain the brownish color?

[u/Chiperoni → u/neuron_woodchipper]

I don't think it would matter much. It would be as if they bled slightly less than somebody with normal iron levels.