Jump to content
Science Forums

Magneto Man


Queso

Recommended Posts

Can someone explain to me why when I smell or taste my own human blood it reminds me of metal?
The usual explanation is that your smell/taste receptors are detecting the iron in your blood’s hemoglobin. As tissues (which are practically all carbon, hydrogen, oxygen, and nitrogen (CHON)) go, blood has a lot of iron in it – about 0.25% by mass, ignoring water, or 0.08% by mass not.

 

I suspect this is an oversimplification, though, as one can dissolve a lot or iron in salt form in water, and the resulting solution has hardly any taste. Something about the way the iron is bound into the hemoglobin is important. It gets more complicated, as hemoglobin is on the inside of red blood cells, and the iron part of the hemoglobin (heme unit) is on its inside, so some sort of mechanical breaking down has to happen before your receptors can contact it. Too broken down, and the iron isn’t as chemically reactive as when it’s in more intact hemoglobin. I’ve not tried testing this, but it suggests that the metallic taste of blood peaks at a certain point in its decomposition.

 

The exact chemistry of how this happens is over my head. I suspect it’s know in detail by the right sort of microbiologist/neurophysiologists, but that it would take a while for a nonspecialist like me to learn the basics required to just follow an expert explanation. Proteins, such as hemoglobin and receptors are big, complicated things compared to most chemical compounds, and take a lot of study to understand well.

 

On top of that, taste is a funny sense, where often two things we think of as tasting similar really involve very different receptor phenomena. Much less is understood, even by experts, about the precise mechanics of taste and smell than you might think.

Link to comment
Share on other sites

well... hemoglobin, the main constituent of blood, and the chemical that transports oxygen to your cells, has at its heart iron atoms. In fact, it's the iron that latches onto the oxygen. As red blood cells die, the hemoglobin degrades and iron (in some form) is released.

 

Maybe????? :hyper:

Link to comment
Share on other sites

Another weird factoid: if you look at your veins close to your skin, you see blue, which is the natural color of your blood: when you bleed, that iron oxidizes when it comes in contact with the air and turns red: its essentially "rusting"....

 

Ironic,

Buffy

Link to comment
Share on other sites

Another weird factoid: if you look at your veins close to your skin, you see blue, which is the natural color of your blood
This factoid is actually a common misconception – old, though perhaps not as old as the mistaken Greek belief that gave arteries their name – that they contain air.

 

Oxygenated blood is bright red. Deoxygenated blood is dull red (blood collected from veins into airtight vials and bags, such as those used for blood donations, is this color). Although veins near the skin appear blue-green, this is an optical illusion. They are actually a dull, gristly grayish color. Because they block the pinkish, capillary-rich tissue beneath them, they fool your vision system into perceiving them as blue-green next to the pink tissue beside them.

 

Try cutting a small hole in a piece of opaque paper, and examining your “blue” veins through it. You’ll be able to perceive their correct, grayish color.

… when you bleed, that iron oxidizes when it comes in contact with the air and turns red: its essentially "rusting"....
This is another common misconception.

 

Compared to the several thousand carbon, hydrogen, oxygen, and nitrogen atoms in each molecule of hemoglobin, the iron and its attached (or missing) [ce]O2[/ce] or [ce]CO[/ce] molecules are practically invisible, in addition to being folded pretty deeply inside this elaborate protein molecule. Its red color is due to structures in the protein called porphyrins. Amazingly, hemoglobin changes from dull to bright red due to subtle changes in the alignment of its complicated structure, somewhat analogously to how a rought surface is dull, while a smooth one is shiny.

 

Rust – oxygen - on iron is redish, and sometimes other colors, due to qualities of its much simpler molecular structure.

Link to comment
Share on other sites

Another interesting piece of blood-related info:

 

The fact that we have red blood is merely a coincidence. Iron (which reddens the blood) is worse at carrying oxygen than chlorophyl, the green stuff in leaves. And there is actually research on the way in to producing emergency blood-transfusion plasmas which contains chlorophyl. Which means if you were in an accident and lost a lot of blood and they don't have blood available for your specific quirky type, you'll wake up the next day with a definite green tint to your cheecks, which will last for quite a few days until your body replaced the missing red blood cells.

 

I'm not too sure about this, read about it sometime in the last year or so, but will look for links!

 

Also, molluscs and crustaceans have blue blood, using copper as the oxidizing agent. But the copper in their blood can carry only about 10% the amount of oxygen than our iron can, so there is definite evolutionary limitations in terms of the maximum size attainable by molluscs.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
×
×
  • Create New...