“Osteoclasts acting together in a small group excavate a tunnel through the old bone, advancing at a rate of about 50 µm per day. Osteoblasts enter the tunnel behind them, line its walls, and begin to form new bone, depositing layers of matrix at a rate of 1-2 µm per day. At the same time, a capillary sprouts down the center of the tunnel. ...Typically, about 5-10% of the bone in a healthy adult mammal is replaced in this way each year”
Alberts, et al. Molecular Biology of the Cell, 4th edition, Garland Science, 2002. pg 1306.
“Constant remodeling of bone is a normal part of skeletal maintenance. ...[Bone] remodeling involves replacing old bone with newly formed bone via the functional coupling of osteoclasts and osteoblasts. ...Bone remodeling enables bone to adapt to mechanical stress, maintain its strength, and regulate ...homeostasis.”
Rubin and Strayer, Rubin's Pathology, 5th edition, Lippincott Williams and Wilkins, 2008. pg 1088.
I am 100% aware that probably none of my readership here is deeply interested in the physiology of bones. I don't really care. It occurred to me the other night that bones, bone remodeling, and the cells that accomplish this task are a physical metaphor of emotional structures and growth*. The osteoclast breaks down what the osteoblast regenerates. The skeleton appears unchanged from the outside but it is ultimately one of the most dynamic structures in the body.
A year ago, my skeleton was fragile: too much breaking down without enough building up leads to a delicateness that lends itself to snapping. The turnover of my physiology was more rapid in degeneration than in growth. I was unable to get from my environment the nutrients and support necessary to maintain myself. The cracks in structure only show when the imbalance has gone on too long.
When the diet does not contain enough calcium or phosphorus, the bones begin to degrade. Calcium is used in other parts of the body for the immense tasks of regulating the functions of essentially all cells, and in the name of maintaining that ability the skeleton will be sacrificed. The osteoclast will break the bone and release the ions into the blood. The skeleton will waste.
A year ago, I gave away more than I had to take up. I poured calcium into the blood; I sacrificed my matrix to maintaining the integrity of other structures. I weakened under a demand that I felt I had a mandate to fulfill.
Tiny cracks began to form in me. I was not strong enough.
In order not to break, there must be a change: either the body demands less from the skeleton, or there there is more calcium made available to the bones. The alternative is unsustainable: the skeleton weakens, and there are new, crush fractures: the spine compresses; the pelvis thins.
A year ago, I had to make a decision: I could either give up less, or try to get more. I was breaking apart and all the structure that made me I was giving away.
My bones and his bones. We wore ourselves down to our ions. We let our osteoclasts work overtime, but skeletons in two separate bodies can't share. We eroded ourselves to the marrow and there was nothing left to do but break.
And we did.
And it hurt.
But a miraculous thing lives in a skeleton: the osteoblast. They wait for a signal and collect calcium; laying it down in giant woven nets to fill in the holes left over from a fracture. The woven bone is weak and can break again easily, especially if perturbed, but with time and support—from a cast, from collagen-making cells, whatever—the structure strengthens.
My osteoblasts are working. They lay down tissue, my blood nourishes it and I take the best care of it that I can. I feed and strengthen my body. I know more now about how to do this.
A year ago, what I thought was taking care of myself actually lead to wasting. I cleaved myself to a love that had become dysfunctional, and so did my partner. We tried so hard. The fracture that we were trying to fix would never heal, its ends were too far away to fuse. Two skeletons in separate bodies cannot repair each other.
I lead a life now that requires that I pour out almost my everything every day. What I take in must be restorative, or else I can't make this work. By necessity, I have learned when to give more and when to give less. I have learned what I need to take. I have discovered that other appetites and other drives sometimes serve me better.
When I open my body to a lover, they give me as much as I give them. We use the same currency. We trade the same ions. I have to pick then with some level of discrimination so that this trade is fair. The weight of another strengthens me.
Weight-bearing activity increases the functionality of the osteoblast. This increases the strength of the skeleton.
I learn new things about my skeleton with every encounter: I learn where old scars make me weaker, and where my remodeled bone is stronger than I expected. I learn where the limits of my strengths are and how the role of a new lover in my life contributes to that. I learn that I make the decisions about what to give myself and what to give away.
My skeleton looks the same on the outside.
For me, it is all newly made. I have turned over my bones. I am rebuilding. I am destroying. I strengthen and adapt. My osteoclasts and osteoblasts are in a delicate balance tipped off by breaking. My new strengths are things I would never trade.
*In case the graphs didn't tip you off, this is a sex blog maintained by a deeply nerdy gal.