Bones protect our organs and offer pivotal support for our muscles. Two types of bony tissues make up our skeletons. The first tissue type is called cortical bony tissue, which is strong and dense. The second type is trabecular bony tissue, which is flexible and much less dense. It is this unique pairing which gives each bone its strong, lightweight nature. In fact, I never grow tired of people’s reactions after they learn that ounce for ounce, bone is stronger than steel. What is more, our bones remodel at a fairly rapid pace. Every 10 years we acquire an entirely new skeleton. The cells carrying out this process are called osteoblasts and osteoclasts.
Bone remodeling and growth
Although osteoblasts lay out new bone matrix, it is osteoclasts that either remove old bone or perform maintenance for new bone growth. Repair of a fractured humerus – the long bone of the upper arm – is a good example.
First, osteoblasts secrete a substrate that fills the space between the broken pieces. Little finesse is exhibited by these cells, however, as they normally overproduce matrix at the injury site. The result conjures up an image of the two halves of the fractured bone stuck in a handful of clay, but this is only the first step. Lastly, osteoclasts chisel off the excess material and create a smooth transition from new bone to old bone. We may imagine this effort as one similar to an artist sculpting a masterpiece with exquisite detail.
How important is calcium?
Despite the incredible benefits of bony remodeling throughout our lifetimes, wholesome ingredients for our skeletons are critical during formative years. This means getting the right nutrition to ward off the growth of soft bones when we are younger (i.e., rickets) and the onset of porous, brittle bones when we are older (i.e., osteoporosis).
For starters, calcium and vitamin D are important. The role of vitamin D is vital because it helps transport the calcium found in dairy products and other food sources through the lining of our intestinal tract and into our bloodstream. At this stage, calcium travels within the circulatory system, with most of it en route for storage in our bones. Stored calcium is in a crystalline form that provides bone strength. In fact, over 99% of the total calcium found in the body is in teeth and bones. But there is much more to calcium than meets the eye.
Including its role in bone health, calcium is one of the most important elements in the body. This claim stems from calcium’s presence within our heart and skeletal muscles. Here it is required for proper functioning. Calcium is also necessary for proper nerve function. If the levels of free, circulating calcium in the blood are low, then this mineral is tapped from its bony storage sites. However, when the appropriate levels of unbound calcium are reached, the bony reserves are restocked. The entire process is akin to a finely-tuned, highly-efficient feedback loop. Other minerals with important roles for good bone health include phosphorus, magnesium, potassium, and boron.
Next week I will explain good habits for the smart and feasible care of our bones.
Kevin Wininger is as a radiology technologist and exercise physiologist at Fisher-Titus Medical Center. With a physician referral, a radiology technologist in the Imaging Services department at Fisher-Titus will conduct a DEXA scan to assess your bone density. Similarly, dieticians from Nutrition Services and exercise specialists from Rehabilitation Services will gladly review diet and exercise strategies to minimize bone density loss. Talk to your doctor about referrals for these services if you think you might benefit.