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SadandFurious t1_irbpm78 wrote

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.

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AMightyOak43 t1_irbr8uf wrote

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.

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SadandFurious t1_irbrt3v wrote

take a look at the chemical structure of chlorophyll vs heme and it’s an even better analogy

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Seicair t1_irc8kcs wrote

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.

Chlorophyll

Hemoglobin

Plants use magnesium and mammals use iron. Other animals use copper and have blue blood.

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whtthfff t1_ird8xsr wrote

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?

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Seicair t1_irddgod wrote

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.

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Pyrrolic_Victory t1_ircfu87 wrote

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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Alpacaofvengeance t1_ircaypl wrote

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.

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Pyrrolic_Victory t1_ircdm3s wrote

This is a “good jaundice” and is actually benifical for the patient as bilirubin is a potent anti inflammatory

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drippingthighs t1_irc1glm wrote

So my poop and pee are mostly blood byproducts?

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thenebular t1_irc34pr wrote

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…)

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mooseofdoom23 t1_irdj5zi wrote

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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drippingthighs t1_irdl30x wrote

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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nill0c t1_irdyskq wrote

Only the pieces that aren’t sufficiently chewed pass through. This can be why people with tooth problems, can also develop digestive problems, since they can’t properly chew their food.

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denizdb t1_irde8l3 wrote

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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[deleted] t1_irdnm2j wrote

[removed]

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NerdOfPlay t1_irdtdjd wrote

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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