Without bones, your trunk would exist a slippery bag of organs. But the stiff models of a skeleton that y'all've seen in science form (or as Halloween decorations) tell only half the story. That's because "the skeleton does more than just hold you lot upwards," explains Laura Tosi Bones are made of living, breathing cells. And they play all sorts of important roles, says Tosi, who directs the Bone Health Program at Children's National Medical Centre in Washington, D.C.
Tiny ear bones comport sounds that assistance us hear. Os marrow — a soft, jellylike substance that fills the hollow interior of the body'south long bones — produces blood cells, both red and white. White blood cells fight infections, while red claret cells evangelize oxygen throughout the body.
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And that'south just for starters. Researchers accept been finding that bones "conversation" with other body parts in surprising ways. As scientists uncover the skeleton's secrets, they're finding clues that may help them cure disease and fifty-fifty grow replacement bones.
Cells chosen osteoblasts (gray blobs forming an oval) create new bone tissue. Robert M. Chase/Wikimedia Commons
The skeleton crew
The framework that gives your body shape is surprisingly decorated. "Bone is a very dynamic organ," notes Marking Johnson. He's a biochemist at the University of Missouri-Kansas Metropolis.
The body's skeleton changes constantly. In a process called remodeling, one-time os breaks down and so that new os tin can take its identify. During childhood, that process allows bones to abound and change shape. In adults, remodeling helps repair harm and preclude bones from becoming brittle.
Cells called osteoclasts interruption downwardly erstwhile bone through a process called resorption. Other cells called osteoblasts take charge of making new bone. Only well-nigh bone cells belong to a third blazon. Called osteocytes, they tell the osteoblasts and osteoclasts what to practice. "If y'all think of remodeling every bit a symphony, the osteocyte is the usher," Johnson explains.
Through childhood and early machismo, the body makes more new os than it takes away. This means the mass — or amount of bone — increases. Manifestly, information technology's hard to mensurate bone mass with the rest of the body's tissues in the way. So doctors approximate bone strength past measuring the density of hard mineral packed into a segment of os. The greater the bone density, the stronger the skeleton.
Cells chosen osteocytes, one shown here, act similar conductors in a symphony, instructing the other os cells what to practise. Wikimedia Commons
To build more os, cells require certain building blocks. An particularly crucial i: calcium. Potent bones depend on this mineral, found in dairy products and many veggies. Bones also serve as the body'southward storehouse of calcium, which is used in plenty of places. For example, calcium drives the chemical reaction that allows the heart to shell. When nutrition doesn't evangelize enough calcium, the body will steal the mineral from the skeleton. That tin weaken basic.
It'south also hard to have good for you bones without enough vitamin D. Information technology helps the body blot calcium. But many people have likewise lilliputian vitamin D. As a result, their basic tin become thin and misshaped.
When it comes to building bone, though, "exercise is the most of import thing," Tosi told Science News for Students. Weight-bearing exercises such equally walking, running, jumping and lifting weights are smashing for boosting bone mass. Exercise makes such a difference, in fact, that professional person tennis players actually have stronger basic in the arm they use to swing their noise.
Exercise probably strengthens bones several ways, says Johnson. Weight-bearing practise causes tiny amounts of damage to bone. Osteoblasts respond by laying down new os to repair the impairment. Information technology'due south like paving over potholes on a bumpy road. That repaving results in denser, stronger bones.
Bones, shown here in an 10-ray, appear white because of the calcium they contain. Asja/Flickr
Conversations between bone and muscle
Only paving over tiny bits of damage explains only role of exercise's benefit to bone. Over the last few years, Johnson'south team has shown the route to stronger basic is far more complex. Scientists used to expect at only bones for the answers, he said. As it turns out, though, muscles also have something to say near bone behavior.
Johnson'south team, likewise as scientists in other labs, have discovered signaling — a blazon of chemic chattering — that goes on betwixt the ii types of tissue. Bones announced to send signals that affect the manner the muscles work. Muscles, in turn, ship signals that alter how bone cells piece of work.
Muscles make molecules that influence the deportment of osteocytes — the conductors — Johnson's team has establish. (A molecule is a group of atoms held together past chemical bonds. Molecules make upwards everything, from cells in the body and building blocks of plastics to the gases in Earth'southward temper.)
Johnson suspects that muscles make many molecules that influence basic. He's working to identify these and what messages they transport to basic. If he succeeds, one day it may be possible to identify drugs or other treatments that crank up the volume on those messages. That might provide doctors a way to direct those osteoblasts to make more new bone, for example. That could strengthen the entire skeleton.
Such treatments might help strengthen weak and brittle basic. Chosen osteoporosis, this status affects many older people and can lead to basic that pause easily.
But this enquiry might too help younger people who accept diseases that weaken or damage bones. One case is brittle os disease. As the name implies, people born with this disorder have delicate bones that interruption easily. Correct now, no cure exists.
Osteoporosis is a status that causes stooped posture, loss of height, and thin, weak bones that suspension easily. Arrows indicate bone growth (left) versus os shrinkage (right). Wikimedia CommonsBuilding os exterior the body
The ability to instruct the body to beef upwardly its bones could help people with a number of skeletal disorders. But sometimes building new bones from scratch would be fifty-fifty amend. Scientists at Columbia University in New York Metropolis are working to practise merely that.
One motivation is helping people with Treacher Collins Syndrome. This illness causes basic in the face up to grow abnormally. People born with the syndrome tend to have tiny or missing cheekbones. This gives their faces a droopy look.
Doctors can supersede these misshaped bones or add together missing bone with surgery. It requires robbing bone from other parts of the body. Surgeons may slice out a chunk of hip bone, for example. After shaping information technology into something that resembles a cheekbone, they'll implant information technology into the face.
This is not ideal, nevertheless. For one thing, it damages the hip. The borrowed bone also tin can be difficult to shape into a perfect cheek or jaw.
And then the Columbia squad is growing replacement bone in the lab. First, they create a scaffold, or frame, from cow bone that's been stripped of its living cells. They cleave the scaffold so that information technology's shaped like a normal, healthy version of the os they want to replace or add. Then they remove stem cells from the patient's body.
What is a stem jail cell?
Stalk cells are special in that they can mature into many different types of cells, including bone. The Columbia squad harvests stalk cells from fat extracted from the patient. They apply these cells to the scaffold and so feed them the nutrients they need to grow into bone cells. After a few weeks, surgeons implant the bony scaffold into a patient'south face.
There, new os will go on to grow into the implant. Over fourth dimension, the new bone will completely eat away the scaffold. Eventually, only the patient'due south bone cells volition remain, Sarindr Bhumiratana told Science News for Students. A biomedical engineer, he is i of the researchers at Columbia working on the bone-evolution projection.
Francis Smith was born with Treacher Collins Syndrome, a disease that affects the basic and tissues of the face. He's pictured at right in 1978 at age 2, earlier having any surgeries. At left: Smith equally he appears today, after more than 20 facial surgeries. He is at present a scientist studying craniofacial sciences at the Academy of Calgary in Canada. Francis Smith
So far, these researchers accept grown and implanted bones only into pigs. Presently, though, they're planning to test this technique in people.
In the not-also-afar time to come, people with facial deformities might be able to get new jawbones or cheekbones built from scratch. "The science of the hereafter is exciting," Bhumiratana said, "and it's going to be fun."
Johnson, Bhumiratana and their colleagues are working to pry still more than secrets from bones. They hope they can let those skeletons out of the closet soon.
Power Words
biomedical engineerAn expert who uses science and math to find solutions to issues in biology and medicine. For case, they might create medical devices such equally artificial knees or find new means to produce tissues for use in the trunk.
bone marrow Thesoft, fat substance inside bones that produces blood cells.
Researchers at Columbia University grow custom bones in the gray-colored tanks at centre. A pump (left) bathes the bone cells with special fluids and nutrients (carmine-colored liquid, right) to help them grow. Sarindr Bhumiratana
bone mass The weight of the skeleton.
bone mineral density A measure of the corporeality of calcium and other minerals packed into a segment of bone.
brittle bone disease A genetic disorder present from birth that causes weak, fragile bones; early hearing loss and short height. It is thought to touch on 25,000 to 50,000 Americans. Symptoms can range from mild to potentially deadly.
calciumA chemic element needed by well-nigh organisms to grow.
moleculeAn electrically neutral group of atoms that represents the smallest possible amount of a chemical compound. Molecules tin be fabricated of single types of atoms or of unlike types. For example, the oxygen in the air is fabricated of two oxygen atoms (O2), but h2o is fabricated of two hydrogen atoms and 1 oxygen atom (H2O).
osteoblast Cells that synthesize new bone tissue.
osteoclast Cells that intermission down and remove old bone tissue.
osteocyte The most common type of bone jail cell. It directs the actions of osteoblasts and osteoclasts.
osteoporosis A status that causes weak, brittle basic that fracture easily.
stem prison cell A "bare slate" cell that can give rise to other types of cells in the body. Stalk cells play an important role in tissue regeneration and repair.
tissue Any of the distinct types of fabric, comprised of cells, which make upwards animals, plants or fungi.
Treacher Collins Syndrome A genetic disease that affects the development of bones and other tissues of the face. The syndrome affects an estimated ane in every l,000 people, causing facial deformities and, sometimes, hearing loss and crack palate.
vitamin D Called the sunshine vitamin, the pare makes this chemic upon exposure to sure ultraviolet wavelengths of sunlight. The form made in the peel isn't agile, but rather a precursor form that can exist stored until needed in torso fatty. The active form of this vitamin is a hormone that helps bone take up calcium. The active grade likewise plays a function in fighting many types of chronic affliction, from muscle wasting and diabetes to certain types of cancer and gum affliction. People who do not spend a lot of fourth dimension outdoors or who wear sunscreen when they do may not brand platonic amounts of vitamin D. Few foods are naturally rich in this vitamin either. So manufacturers fortify some commonly consumed foods, especially milk and some orange juice, with vitamin D.
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