Your Living Bones

My three-year-old daughter peered into the casket with me. Curious, her pigtails bobbing, she looked down at the once-familiar face, now just a lifeless mask. We were attending a funeral for a pastor I had known since I was a boy. The body of the vital, active pastor was now still and quiet in his casket, ears unhearing and eyes unseeing. The contrast between it and my energetic toddler was marked. All biological life has its limits, and we all are eventually reduced to a collection of bones in the grave.

Most have seen a model skeleton in school or a doctor’s office, and most are aware of the obvious uses of bones in the musculoskeletal system. They give shape to the human body and provide muscular attachment points, levers for movement, and protection to our vital organs and central nervous system. Some are even aware that bones function as a reservoir of minerals and that they manufacture red blood cells. Otherwise, to many they take the form of dried out, hollow objects that might as well be rattling, plastic decorations used in pagan observances for the dead.

Living bones, very different from the lumps of calcium that make up dead skeletons, are an amazing marvel of design and redesign.

Bone Construction Zone

Far different from lifeless bones in a casket, living bones change beneath skin, blood, and muscle tissue. Like demolition and construction crews, cells with specific functions are constantly remodeling bone. Shaped in the womb, bones continue to adapt through life in a very dynamic way, seemingly reactive and awake to the outside world.

Bones remodel themselves in response to loads or impacts placed on them, like starting a new sport or a physically demanding job. In order to remodel, they must demolish old or less used bone through very specifically designed “demolition cells” called osteoclasts. Located on the surface of the bone, demolition cells get their chemical instructions from their counterparts, bone-producing “construction cells” called osteoblasts.

In response to chemical signals from the construction cells, demolition cells manufacture their own “tools” called enzymes that break down bone. Even one enzyme is incredibly sophisticated—a three-dimensional molecule composed of intricately sequenced, arranged, and folded proteins. The complexity and design of one bone cell’s enzyme can make a multi-billion-dollar New York City high rise construction project seem like the result of children playing in a sandbox. Responses to load needs, the creation of blueprints for new bone, communication between crews, and many more factors form a breathtaking interplay.

In nature, dead bones fall apart at the joints as the body decays. However, living bones are held together at the joints with very specifically designed connective tissues: cartilage, ligaments, muscles, and tendons. Joint connective tissues have their own nerve and blood vessels that nourish cells even more reactive and dynamic than those that are found in bone. Joints allow for work and play, enabling us to do everything from build the skyscrapers in New York to type on a keyboard while juggling a cup of coffee.

Less obvious, however, where living bone meets living bone, deep within joints, lie important nerve endings called proprioceptors. These nerve endings are fired by joints moving or the stretching of connective tissue within joints. Signals then fire up the spine through dedicated pathways to the sensory cortex of the brain. Sometimes called the “sixth sense,” proprioception is the sensation of bodily movement and position. It is this feedback that most obviously provides the capacity for accurate execution of complex movements made by our skeletal bones as they organize to help us accomplish our daily tasks.

Would you believe, however, that movement of bone at the joints plays an important part in brain function?

The Life Is in the Blood—and the Blood Is in the Bones

Proprioception is how our joints “talk” to our brains. Famed animal behavioral expert Temple Grandin illustrated the power of proprioception in her use of a “squeeze machine” to calm beef cattle by stimulating nerve endings in their joints and body tissues. Proprioception is also at work when we swaddle babies, get a massage, receive chiropractic care, exercise, and even use weighted blankets, which are increasingly popular.

The reticular activating system processes hyperalert “alarm” activity in the brain. It is moderated and calmed when the body sends signals to the brain regarding position and movement. In several studies, such stimulation has been linked to decreases in blood pressure. Much like a computer reset button, our brain’s fight-or-flight mechanisms are reset to rest-and-recovery mode by proprioceptive feedback. All this results from the stimulation of nerve endings deep within our joints, where bone meets bone.

Scripture tells us that life is in the blood (Leviticus 17:11). Dried-out, hollow bones truly are devoid of blood and blood’s associated life. However, not only do living bones have blood in their inner core; soft, spongy marrow found in that same core actually manufactures blood. Red blood cells, white blood cells, and blood platelets are all produced by bone stem cells found in the marrow. Long bones stop producing blood in adulthood, and their marrow is turned into yellow marrow or fat. However, even then, our kidneys can signal the yellow marrow to resume blood production if needed. Within bone marrow, we see refined manufacture of living cells, feedback, and communication that are yet impossible for medical science to accomplish.

The Valley of Dry Bones—Dead Forever?

Eventually, all living bones, no matter how dynamic and vital, will die. Joints decay and bones become disjointed, inanimate white lumps of calcium. Once so beautifully animated, they become mute and still in death. The Creator fashioned and designed our bones so artfully. Yet in death, bones dry out and all blood-producing marrow disappears. The life that seemed to animate these once-living cells fades all too quickly, like a passing breath (Psalm 144:4).

Can dead bones live again? Can our Creator breathe new life into inanimate calcium? Long ago, a priest named Ezekiel was asked that exact question. Ezekiel was shown a vision of a great valley full of “very dry” bones, and he was asked, “Son of man, can these bones live?” Ezekiel deferred, “Oh Lord God, You know.” Then the Eternal spoke: “Surely I will cause breath to enter into you, and you shall live. I will put sinews on you and bring flesh upon you, cover you with skin and put breath in you; and you shall live. Then you shall know that I am the Lord” (Ezekiel 37:1–6).

Far more than dried out, used-up lumps of minerals, our incredible living bones fulfill numerous functions, woven into other systems in a way that reveals a thoughtful designer. Bones are built, demolished, and rebuilt in response to environmental demands through the marvelous teamwork of living cells. Where bone meets bone in the joints, bones “talk” to the nervous system. Bone marrow produces blood cells that carry nutrients and oxygen and drive immune function.

Living bones inevitably die, and loved ones die all too soon. Yet dead bones will live again when they are called from the grave and clothed once more in flesh—when new life is again breathed into them by the Creator Himself. Familiar, beloved faces lost to the ravages of time will awaken to breathe, smile, and laugh once more. The Creator who made and fashioned our amazing skeletal bones can remake and refashion them again—and one day, He will do exactly that.