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Physical properties[edit]

I noticed that there is all kinds of info on the cell structures, and compounds within bone, but no properties describing the density, the tensile/compressive strength, dimensions or other physical properties. --THE FOUNDERS INTENT PRAISE 17:50, 13 December 2012 (UTC)

You mean aside from the section called "Mechanical Properties"? HCA (talk) 03:17, 14 December 2012 (UTC)

Composition of Bone[edit]

Dear Wikipedia, Something's not right here. The human body is 1.4% calcium by weight [1]( and bones make up 12 to 15 percent of the human body by weight [2] (lower estimate, multiple sources), and they are "formed mostly of calcium phosphate in the chemical arrangement termed calcium hydroxylapatite" [3] (, up to 50% of bone weight [4] ( If you assume that every calcium atom in the body is in bones 9not likely) and take calcium to be roughly 40% of hydroxylapatite (Ca5(PO4)3(OH)) by weight, then bones are either less than one-third hydroxylapatite by weight on average, <= 0.014/0.12/0.4, or bones make up less than 10% of body weight. Based on this, I would believe bones are probably composed mainly of collagen (>40%), so statement [3] should be changed. But if not, which of these other statements are incorrect? As it stands now it makes no sense to me, hydroxylapatite may compose up to 50% of some bones or bone parts, but the average must be much lower. And while we're discussing this, why not provide an estimate for the weight percentage of bone in the human body on one of the wikipedia pages. (talk) 20:59, 29 April 2013 (UTC)

Bone is about 50/50 mineral/collagen, but there are other things too - water, cellular material, cartilage at the ends, the marrow inside, blood vessels permeating bones, fat (yes, plenty of fat in bones; that's why freshly extracted, raw bones are yellow and, if not degreased, will ooze foul-smelling yellow fat). I suspect the 12-15% is wet-weight of freshly extracted bones - I know from skeleton preps that bones get lighter and lighter as I take steps to strip away all the extraneous "stuff" to leave just the mineral and collagen.
Still, you're right about the phrase "formed mostly of calcium phosphate" as vague and misleading, and I'll alter it. HCA (talk) 14:54, 30 April 2013 (UTC)

Thanks, that helps a bunch. It seems within the 12-15%, one-third is marrow ( Subtracting all the marrow, fat and water, and taking 96.5% of the body's calcium to be in bones (to balance the Ca/Mg ratio in the rest of the body), I have calculated that dry bone tissue makes up about 7% of the human body by weight and is comprised of about 50% hydroxylapatite, 40% collagen, 6% carbonate, 1% citrate, 1% osteoproteins(o-lactin,o-nectin,o-pontin,o-protegerin), 1% proteoglycans and 1% minerals(Na,K,Mg,Ca,Mn,Fe,Cu,Zn,Cl,I) by weight. On the other hand, the bulk chemical composition of living bone tissue, marrow and all, I've estimated as follows: 27% water, 26% hydroxylapatite, 21% collagen, 10% triglycerides, 6% hemoglobin, 3% carbonate, 3% cholesterol; citrate, minerals, osteoproteins, proteoglycans, phospholipids and nucleic acids (0.5% each); 0.2% adipoproteins(a-nectin,resistin,leptin,apelin), 0.05% anion exchanger protein, 0.05% other proteins and 0.01% glucose That is by weight of course, does anything there seem out of whack? (talk) 22:23, 1 May 2013 (UTC)

What is the role of Matrix gla Protein?[edit]

The Matrix gla protein article says that MGP "may participate in the organisation of bone tissue". Can someone add more about the role of MGP in bone to this article?
Encyclopedant (talk) 03:03, 22 November 2014 (UTC)

Explanation of some changes[edit]

Have made some changes:

  • Reinstated the 'composition' heading. The 'Layered' section goes from out to in, whereas 'composition' covers the nature of the tissue.
  • Renamed tumours to 'cancer'. To me at least, the word 'tumour' implies a swelling (OED: [1]), whereas I am referring to different disease processes and also examples of cancers that affect bone marrow.

Cheers! --Tom (LT) (talk) 05:46, 7 December 2014 (UTC)

Comparative aspects[edit]

I notice that much of what has been written is actually about human bone. Some of that is true for a much greater range of taxa, but other parts are specific to humans, or appear to be. I will try to clarify that, to the extent that I can, and add some comparative material, which is currently almost non-existent on that page. — Preceding unsigned comment added by Michel Laurin (talkcontribs) 20:34, 18 September 2015 (UTC)

Please, feel free to add as much as possible; many anatomical articles here are hugely anthropocentric. HCA (talk) 16:18, 19 September 2015 (UTC)