Calcium and Bone Broths

[Guest guest]

I spent too much time trying to gather scattered thermodynamic and solubility

data from various sources and to recover the correct formulas from my 80+

pages of Chem 2 notes, and when I tried to put it all together I ended up with

some sort of error calculating it, so I'll have to check it out again tomorrow

when I'm not so tired.

But we should be able to calculate how boiling would increase the solubility

equilibrium for calcium carbonate and calcium phosphate with

K=e^(-detaGstandard/RT) for T=373K (boiling) if one gets the standard change in

free energy

from a selected thermodynamic data chart.

In the meantime, it seems clear to me that if the collagen dissolves, it's

simply impossible for the calcium salts to remain in the bone. I suspect that

any associated salts would come out with the collagen, and any remaining salts

remain with their associated collagen. The leftover bone is probably that,

plus other connective tissue like the dense irregular connective tissue that

makes up the periosteum.

Considering that collagen is an absolutely massive molecule compared to the

ionic salts that accumulate with it, and that these salts make small enough

crystals to fit inbetween the spaces in collagen fibers, it seems utterly

counter-intuative to me that big collagen molecules can fall right out with

these

tiny salts suspended in-- what, air? That seems to me like removing your

shelves

and expecting your books to remain in place, or removing a Chinese Checkers

board from underneath the marbles and expecting them to remain in position.

From Grabowski, _Principles of Anatomy and Physiology_, 2003:

" It was once thought that calcification simply occurred when enough mineral

salts were present to form crystals. Now, however, we know that the process

occurs only in the presence of collagen fibers. Mineral salts begin to

crystalize in the microscopic spaces between collagen fibers. After the spaces

are

filled, mineral crystals accumulate around the collagen fibers. The combination

of crystallized salts and collagen fibers is responsible for the hardness

that is characteristic of bone.

Although a bone's hardness depends on the crystallized inorganic mineral

salts, a bone's flexibility depends on its collagen fibers. Like reinforcing

metal rods in concrete, collagen fibers and other organic molecules provide

tensile strength, which is resistance to being stretched or torn apart. Soaking

a

bone in an acidic solution, such as vinegar, dissolves its mineral salts,

causing the bone to become rubbery and flexible. "

Chris