Submitted by DwagonFyre t3_xxadwj in askscience
I understand that bruises are formed by small amounts of blood being released into the tissue beneath the skin, but where does that blood go as the bruise fades?
Submitted by DwagonFyre t3_xxadwj in askscience
I understand that bruises are formed by small amounts of blood being released into the tissue beneath the skin, but where does that blood go as the bruise fades?
Is the staining what makes bruises look brown/yellow/green as it heals?
Bilirubin is a brown/yellow compound produced by the degradation of hemoglobin. Various concentrations lead to various fading colours
Edit : see the answer of SadandFurious, it is much better
Unusual but related question, would a regularly-high Bilirubin count (showing in a blood test) cause bruises to fade slower?
Clinical scientist here, I analyze bilirubin (and other things) in blood.
An abnormally high bilirubin makes people look yellow, or "jaundiced." Also, high concentrations make your blood plasma (the liquid part of your blood) look much darker than normal. (Most plasma is light yellow, similar to urine). But a high bilirubin plasma will be dark yellow to green to black! And it stains the glass test tubes with its color. Interesting and not really something I knew till I started my career. Thought I could share
if anyone is curious, people who have abnormally high bilirubin generally have a condition called Gilbert's Syndrome.
>Gilbert's Syndrome
Which is mostly harmless/asymptomatic (and very common), apart from intermittent jaundice and some possible links to fatigue and other diffuse symptoms.
It might be more accurate to say that people who have Gilbert's are often jaundiced.
There are loads of causes of juandice. Some of them are really bad news.
It can be pre hepatic (like haemolysis), intra hepatic (like Gilbert's) or post hepatic (like gall stones).
Other things that you'd have to consider would include drug reactions, pregnancy, biliary obstruction, autoimmune causes (haemolysis, hepatitis...) Other causes of hepatitis (viral, anaesthetics, alcoholic...), I forget the rest of the list. It's not hard to find out you want to know the other causes.
The most likely causes are also different at different ages.
Gilbert's is one of many.
Absolutely, all it takes is a blood test to diagnose. I have gilbert's, but had no idea until a doctor noted it during a blood test for something else. I had always wondered why sometimes by eyeballs were yellow like I had cancer, or my skin got yellower sometimes.
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Is it possible that the black samples are coming from people who have tattoos? I know in the heavily tatted cadavers, the lymphatic fluid is grey/black. The ink gets stuck and circulates. Idk anything about the color patterns of bilirubin but it would be really freaking interesting if that were why your samples were black.
That's a really interesting thought! But it's not the same reason. Lymph would obviously be more affected by tatoo ink, as macrophages engulf the metal in the tattoo ink, and then return to the lymph.
Really interesting to learn that about lymph. very much appreciate the additional info, but no, the high bilirubin making plasma look dark yellow, greenish or kinda black (called "icteric") is only from bilirubin.
Also it's not really black, just a very very dark greenish yellow.
Additionally, some medications can make the plasma look kind of green.
The lymphatic system is over of the least talked about complete systems in the body. It's like those illustrations of the circulatory systems and the nervous systems and then years later biology teachers are like 'oh, yeah, there's another one too' and then right back to floating over it.
Seems like it's that way because it was so elusive anatomically and low key for the most part, but just like hormones are crazy important to how we work, the lymphatic system is crazy important to how things keep working. I think most people, if they even think about it, assume everything flows back directly into the circulatory system, but aside from gasses, that seems like mostly an outbound channel.
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Thank you!
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Bilin, a byproduct of breaking down hemoglobin. It's also why poop is brown.
Also the colour of the bruise depends on the colour of your skin. As your skin obviously overlaps the bruise and causes a distortion in the colour.
Many thanks. You explained it very clearly.
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I can imagine that would be kinda terrifying. I'm a worrier in the first place, but I'd be constantly worried that there was something internally wrong.
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Would gentle massaging of a bruise help is go away faster?
No
On the contrary, it's likely to cause more damage, rupture blood vessels, and increase healing time
What's the best practice then? Maybe neosporin and otherwise don't touch it? Soaking it in a bath helpful at all? Does intentionally reducing inflammation (e.g., by ibuprofin or a topical steroid) potentially hurt the process?
Neosporin wouldn't help. A bath may increase good blood flow but probably won't improve on the bruise healing to a noticeable degree. Ibuprofen can make blood thinner and increase bleeding so would be counterproductive at least right away. I don't know what if any benefit steroids would have.
Bruising often accompanies injury or trauma - some treatments may decrease pain and swelling making the area look better but not necessarily healing the bruising faster.
What WOULD help it heal faster?
Eating a well-balanced diet. Assuming you're otherwise healthy, nutrient deficiencies prolong wound healing.
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Neosporin is an antibiotic, used to prevent or treat minor infections. If the bruised area included broken skin (a cut, scrape, puncture, or burn that compromised the barrier the skin provides) then applying neosporin or another topical antibiotic could be beneficial
There is no reason to apply an antibiotic to a plain bruise
National Domestic Violence Hotline website as this line of inquiry is potentially concerning
If your body is otherwise healthy then you should just let it do its thing. If you're not otherwise healthy then the list of possible answers varies (into opposites) depending on what else is wrong. Example: (as I understand it) a warm bath should dilate blood vessels in the skin. A cold bath will contract surface vessels and dilate deeper ones. Hot and cold aren't the only things that will dilate/contract blood vessels though -- a bruise for instance...
A bruise is a result of damaged cells. There will be cleanup and rebuilding going on. Conscious Interference is unlikely to help unless you know exactly what to do, but in that case you probably also knew what to do to build a strong healing response so just relaxing would be your best bet.
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Anything that increases blood flow (hot baths, exercise, sunlight,etc) will increase the inflammation response. This is why fevers are a thing and generally why being static and immobile causes wounds to take forever to heal
I've read studies about using leeches to help "clean up" bruises more quickly. Of course you then have the bite mark to contend with...
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I recently had an iron infusion due to anemia, and I noticed that the bruise from the IV lasted way longer than bruises typically do on me. Could this be due to "liberated iron"?
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Does this also apply to petechiae?
What role do the cenobites play?
Do you smell vanilla ?
Excreted as waste: my understanding is that poo is brown from dead red blood cells tinting it.
It's not dead RBCs that make feces brown. It's a byproduct of hemoglobin catabolism called stercobilin.
Dying RBCs are removed from circulation by the spleen, and the hemoglobin inside them is split into its heme and globin components. The iron is then removed from the heme group. The remainder of the heme is a yellow pigment called bilirubin. Bilirubin is then put into the bloodstream and makes it's way to the liver. Liver cells remove bilirubin from circulation and package it into bile. Bile is released from the liver and gallbladder into the small intestine to aid in the digestion of fats. The bilirubin then works its way through the rest of the GI tract. In the colon, bilirubin is converted by bacteria in other pigments. One of those pigments, stercobilin, is brown.
And that is why feces are brown. It's also why the feces of a person with liver failure or a bile duct obstruction will be gray/white and fatty.
Edit: bike -> bile
The human body is fascinating. Recycling dead RBCs into Iron for presumably new RBCs, and the remainder into bile for enhanced digestion. The body really knows how to use everything to its fullest extent.
The bilirubin in the bile isn't the part that aids in digestion. Bile is a mixture of quite a few things. Some of those things, like bilirubin, are wastes that the body is eliminating in the feces. Other components are functional.
One of the functional components of bile is bile salts. Bile salts are produced in the liver and they aid in digestion by emulsifying fats. Emulsification is important because it makes it easier for the enzymes that digest the fat (lipases from the pancreas, mainly) to access it.
They're called salvage pathways. It's a lot less energetically expensive to recycle.
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Forgive my ignorance here but I thought the spleen was more of a useless organ? And we could live fine without one?
You can live without the spleen because, after its removal, the liver and kidneys will take up its functions.
But the spleen is an important part of the lymphatic and immune system. The same is true for the tonsils and appendix, which are also lymphoid organs that can be safely removed.
I needed my damaged spleen removed as an adult. The doctor said that basically nothing would change for me after losing my spleen. From what I remember him telling me the spleen is more important in younger children as an immune defense but all he said to me was that I should make sure to stay up to date on my vaccinations. It probably helps that I’m relatively young and am in good health but I’ve noticed no differences in the years post splenectomy. The spleen isn’t useless but it’s far from vital.
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What about a bruised ego?
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Does this account for like large amounts or long term internal bleeding that surfaces to skin visibility as well?
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Would it help healing to use a needle and syringe to suck out the bruise?
Is it normal for a bruise to leave a stain for a long time? I clipped my thigh on a tablecorner like, 2 months ago, and I can still faintly see the spot in a bright light
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To add on to others, the reason your skin tends to look yellow as bruises progress is because of biliverdin (green pigment)/bilirubin (yellow), 2 intermediate products in the breakdown process of the heme group, which is the iron-containing, red pigment, O2 carrying part of hemoglobin in red blood cells (RBCs).
This is in essence the same reason people with liver failure and hemolytic disease (diseases that destroy RBCs) tend to have yellowing of their skin and eyes (jaundice). Macrophage (big eater) cells in the spleen/liver eat and break down old RBCs, and the resulting bilirubin is conjugated into a soluble form and excreted in bile, which helps emulsify fats in your small intestine.
We can take this even further- the bilirubin is eventually converted by gut bacteria into stercobilin, which makes poop brown, and urobilinogen, which is partly reabsorbed and leaves through the kidneys as urobilin, which makes pee yellow. So as you can see, that heme group in hemoglobin responsible for coloring a lot of our fluids.
It's like leaves in the Fall, with chlorophyll being equivalent to hemoglobin and the anthocyanins and xanthophylls and carotenoids take over and cause different colors.
Edit: oh, I should have added: According to day length, the chlorophyl breaks down, leaving the other chemicals to shine their colors.
take a look at the chemical structure of chlorophyll vs heme and it’s an even better analogy
Pyrrolidines everywhere!
For those who want a visual reference, here are example types of two sub regions of chlorophyll and hemoglobin that show the similarities.
Plants use magnesium and mammals use iron. Other animals use copper and have blue blood.
Wow, never knew this. Do we know why mammals use iron? Like is it somehow better for what mammals do, or is/was there just a lot of it available?
I don’t know the evolutionary reasons behind it. All vertebrates with the exception of one Antarctic icefish use hemoglobin or heme to transport oxygen, but a lot of invertebrates use hemocyanin (copper based, blue blood), and there are multiple different iron containing compounds that are in use among invertebrates.
I found this article that you might find interesting.
https://www.quantamagazine.org/icefish-study-adds-another-color-to-the-story-of-blood-20190422/
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Tetrapyrolles are the foundation of life on this planet and allow us to eat sunlight!
From Cyanobacteria (and later plants) who evolved in order to use them to create chlorophyll and capture photons and use that energy to turn CO2 into reduced carbon chains which form sugar/fat and O2, to mammalian cells (among others) who use them to create hemoglobin(from heme) which then carries the O2 to the mitochondria where we oxidise these reduced carbon chains back to CO2 and energy in the form of ATP.
The breakdown products of both heme and chlorophyll are anti inflammatory/anti oxidative in nature, and have roles to play in aging too.
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Another very common cause of jaundice is Gilbert's syndrome where the blirubin isn't conjugated as efficiently and can give a yellow-ish appearance. Around 5% of the North American population have it, but it doesn't cause any clinical problems.
This is a “good jaundice” and is actually benifical for the patient as bilirubin is a potent anti inflammatory
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So my poop and pee are mostly blood byproducts?
Your pee is entirely blood byproducts (as the kidneys only filter your blood), your poop is mostly blood byproducts, as your digestive system is really good at absorbing almost everything that you eat. So there's also fibre in there along with anything that couldn't be broken down in time as it moved through (corn, nuts, etc…)
Whoa whoa whoa. The kidneys only filter blood?!
If corn and nuts can’t be broken down in time, does that mean that your body does not absorb the full caloric value of the thing?
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can no corn be broken down ever? i always wonder why they appear in the toilet. why do ppl eat it then?
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also, what % of maximum nutrients does the body absorb before it poops? is it like 99%? as a kid i always thought maybe there was an inefficiency and possibly reeating it (obv not a good idea) would help absorb the rest
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Would you happen to know why I don’t get discolouration when I bruise? I’ve sprained ankles, broken bones, fall often, and never have yellow/purple spots.
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The short answer is a fat content in the 'runnier' earwax.
The interesting thing is this trait is determined by a gene called ABCC11 that also causes people with dry earwax to also have no body odor!
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So if we heal from a lot of bruises we poop more?
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Is this further support for letting inflammation do it’s thing and NOT reducing it through the application of cold etc.? It seems to be lots of research coming out that suggests leaving the inflammation alone is best for the fastest healing.
In general cold/ice compression and NSAIDs slow wound healing. Keep in mind that many people will accept a few extra days healing in return for pain relief and that sometime inflammation happens without real damage.
Yeah, the average weekend warrior athlete will just take off an extra week(end) while popping Tylenol.
A professional athlete will have a trainer monitoring and working on healing faster.
Tylenol (paracetamol, or acetaminophen if you're American) will not slow wound healing
So people are scared of inflammation mainly because it causes pain despite it also promoting healing? Is inflammation always good then
No, there are many types of inflammatory diseases. (i.e. Asthma) For sprains and scraped knees just let it be, but there are always going to be exceptions to the rule.
Maintaining a healthy inflammation response is daily overlooked in many people.
As a best case scenario for an otherwise healthy person I totally agree. Until the inflammation really is too much for one person to handle.
What's considered too much inflammation?
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Yes. Inflammation is a good thing, but it must be monitored or it could over do it and cause more damage. The general advice is to start with cold just after the injury to reduce the initial inflammation, then relatively soon after switch to warm for a longer period, then alternate with short periods of cold with longer periods of warm.
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Cells known as phagocytes and other immune cells/proteins break down the blood to be reused
If it's a foot injury, your bruise moves. When I broke a small bone in my foot, my doc warned me not to panic if the bruise moves around. I thought he was a quack until the huge bruise that started on the side of my foot moved to my toes. The body is weird.
Also, some of the pain moved with it. My toes hurt like hell till the bruise finally went away.
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So I have a question, I healed quickly as a kid and still do, the only thing that has changed is the increased visibility of scaring, I still heal quickly it's just that scars seem to be much more apparent then I feel they use to, why, is it just a getting older kind of thing? (I'm 36)
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BallardRex t1_irb3z6t wrote
The short answer is that a number of cells are recruited to “eat” and otherwise break down the debris, especially the erythrocytes, which are ultimately either recycled in part or excreted as waste after processing in the liver/spleen. In particular the “eating” is carried out by leukocytes which are recruited to the area via the inflammatory process. Depending on severity and location of the bruise there might be some residual staining from the liberated iron, but that will usually also fade with time in a healthy person.