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Bone RemodelingBone Remodeling: process involving bone formation and destruction in response to hormonal and mechanical factors-Controlled by thyroid and parathyroid glands in response to calcium levels in the blood. (9-11 mg/100ml)

Absorption: using excess calcium in blood to build more bone (aka bone deposit)Resorption: Breaking bone down to release calcium ions into blood when calcium concentration is low.When healthy, bone deposit = bone resorption1

How it works

Thyroid gland: Gland that secretes calcitonin in response to high calcium levels in the blood. Hormone: Calcitonin: hormone that signals the absorption of calcium into bones. Builds more bone.

Parathyroid Gland: Gland that secretes parathyroid hormone.

Hormone: Parathyroid hormone: Hormone that signals the resorption of calcium from bones. Bones get smaller.2Bone Remodeling: Negative Feedback MechanismBones are remodeled in response to two factors:Calcium levels in the blood (blood-calcium ion concentration)Mechanical stress

3Bone Remodeling: The castPeriosteum: Double layer connective tissue that lines outside of bone. Houses osteoblasts and osteoclasts. Serves as an anchor point for muscles and ligaments.

Endosteum: Double layer connective tissue that lines inside of bone. Houses osteoblasts and osteoclasts. Serves as an anchor point for muscles and ligaments

Osteoblast: Bone building cellsOsteoclasts: bone digesting cells

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Normal Bone RemodelingNormal Bone remodeling is a negative feedback mechanism controlled by calcium ion concentrations in the blood.

Too much calcium = more bone built Too little bones are broken down

When healthy, bone deposit= bone resorption

Each day, up to gram of calcium enters of leaves your bones

Each week, 5-7 % of skeleton is remodeled.

Your entire skeleton is remodeled every 12 years.5Vitamins are essential

Vitamin D: aids in absorption of calciumVitamin A: helps in the balance of bone deposit and resorption

6MechanismNormal calcium ion concentration in blood = 9 -11 milligrams/100 ml of blood7Bone Remodeling: Negative Feedback Mechanism

89Loss of Bone Homeostasis

Loss of Homeostasis in BonesOsteoporosisPagets Disease of BoneOsteomalacia (rickets)Bone SpurOsteoarthritisOsteititis deformansFybrodisplasia ossificans progressiveOsteochondritis dissecansOsteogenesis imperfectOsteoitis fibrosa cysticaOsteomylitisCondensing osteitis

What happens (what goes wrong?)Who is typically affected? Why?How is it treated?What other parts of the body are affected?

10Loss of Homeostasis in BonesOsteoporosisPagets Disease of BoneOsteomalacia (rickets)Bone SpurOsteoarthritisOsteititis deformansFybrodisplasia ossificans progressiveOsteochondritis dissecansOsteogenesis imperfectOsteoitis fibrosa cysticaOsteomylitisCondensing osteitis

What happens (what goes wrong?)Who is typically affected? Why?How is it treated?What other parts of the body are affected?

11Bone Remodeling: Negative Feedback Mechanism

12Bones Also remodel as a result of stress, sometimes on purpose

Wolffs law: bones are remodeled/replaced in direct response to the amount of stress placed on them.

Bone deposit: adding bone to areas that are stressed or damaged.

1314Signal Transduction in Electrically Stimulated Bone CellsBY CARL T. BRIGHTON, MD, PHD, WEI WANG, MD, RICHARD SELDES, MD,GUIHONG ZHANG, PHD, AND SOLOMON R. POLLACK, PHDInvestigation performed at the Department of Orthopaedic Surgery, University of Pennsylvania, Philadelphia, PennsylvaniaBackground: Electrical stimulation is used to treat nonunions and to augment spinal fusions. We studied the biochemicalpathways that are activated in signal transduction when various types of electrical stimulation are appliedto bone cells.Methods: Cultured MC3T3-E1 bone cells were exposed to capacitive coupling, inductive coupling, or combinedelectromagnetic fields at appropriate field strengths for thirty minutes and for two, six, and twenty-four hours.The DNA content of each dish was determined. Other cultures of MC3T3-E1 bone cells were exposed to capacitivecoupling, inductive coupling, or combined electromagnetic fields for two hours in the presence of variousinhibitors of signal transduction, with or without electrical stimulation, and the DNA content of each dish wasdetermined.Results: All three signals produced a significant increase in DNA content per dish compared with that in the controlsat all time-points (p < 0.05), but only exposure to capacitive coupling resulted in a significant, ever-increasingDNA production at each time-period beyond thirty minutes. The use of specific metabolic inhibitors indicated that,with capacitive coupling, signal transduction was by means of influx of Ca2+ through voltage-gated calcium channelsleading to an increase in cytosolic Ca2+ (blocked by verapamil), cytoskeletal calmodulin (blocked by W-7), andprostaglandin E2 (blocked by indomethacin). With inductive coupling and combined electromagnetic fields, signaltransduction was by means of intracellular release of Ca2+ leading to an increase in cytosolic Ca2+ (blocked byTMB-8) and an increase in activated cytoskeletal calmodulin (blocked by W-7).Conclusions: The initial events in signal transduction were found to be different when capacitive15Bones Designed to Bear Weight

Broken Bones and Bone Disorders

What can go wrong?How is it fixed?1617Bones will reinforce where needed

18Wolffs Law: a bone grows or remodels in response to demands placed on it. All bone growth, repair, and remodeling is controlled by hormones

19When stuff goes wrongBone Stress and Wolffs LawTypes of FracturesBone DepositTreatment

20comminuted

21comminuted

22Comminuted

23Compression

24Spiral

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26Epiphyseal Fracture

27Depressed

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29Greenstick

30Treatment

31When things go really wrong

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34Homeostasis35Osteoporosis: Bones lose most of their supportive capacity. Why?

36Pagets Disease

37Cheap Bones

38Pagets

39Types of pain Bone pain: Small breaks called micro fractures can occur an pagetic bone. These breaks can cause pain, especially in in weight-bearing bone such as the spine, pelvis, or leg. Joint pain: cartilage can be damaged when Paget's disease, reaches the end of a long bone or changes the shape of bones located near joints. This can result in osteoarthritis and joint pain. Muscle pain: When bone is changed by Pagets Disease, the muscles that support the bone may have to work harder in different angles. Nervous system pain: bones enlarge by Pagets disease can put pressure on the brain, spine cord, or nerves. Cause- headaches, neck pain, back, and legs. *There is no cure for this disease* Advil and ibuprofen helps for pain 40The image below shows this patient's skeleton as seen on a bone scan. A tiny amount of radioactive medication was injected into her vein; this attaches to areas of bone remodeling. Then a scanner, which is essentially a Geiger-counter that can take images, moves over the entire body. Normal bone is light grey and abnormal bone is black. This patient has Paget's disease in the skull, the right shoulder, and the left pelvis and leg. The corresponding x-rays show the thick, deformed bones. Compare the normal sides to the abnormal sides, especially at the shoulder and the femur.

What it does to the bone41Fibrodysplasia Ossificans Progressiva (FOP)Causes Skeletal Muscles and Soft Connective Tissue to turn into BoneLocks JointsCaused by a mutation in the gene that codes for activin receptor type IAOnly 600 Cases Documented GloballyPredicted that 2500 People Have it Symptoms Are Painful SwellingThere is NO Known Cure

42Fibrous Dysplasia

BY: Chelsea Neal43

Uneven growth PainBrittle bonesBone deformation Fibrous dysplasis is a chronic disorder in which bones expand due to abnormal development of fibrous tissue, often resulting in one or more of the fallowing:

44FemurTibiaRibsSkull

Facial bonesHumerusPelvisVertebrae in the spine

Any bone can be affected. More than one bone can be effected at any one time, and when multiple bones are effected, it is not unusual for them all to be on one side of the body. However, fibrous dysplasia does not spread from one done to another. The most commonly affected bones include the following:

45Osteomyelitis

46Inflammation or swelling of bone tissueUsually the result of an infection, sometimes due to traumatic injuryAffects children and adultsOften involves vertebral bonesIndividuals with weak immune systems are more likely to develop this47Charcot Neuropathy From very minor trauma or prolonged walking, small areas of stress can build up in the bone or in a joint leading to a crack or a stress fracture The patient with diabetes is unable to perceive the painThe stress crack in the bone now begins to get worse and develops into a fracture. The fracture also gets worse as more walking occurs on the injured foot or ankle. Very significant bone deformities can result from this condition, called Charcot Disease.

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49An abnormal bone formation in children resulting from inadequate calcium in their bones. Lack of calcium can result from not enough calcium in the diet, Inadequate exposure to sunshine (needed to make vitamin D), or not eating enough vitamin D. Rickets is a failure to mineralize bone. Rickets

50The Elephant Man

51The StoryJoseph Merrick was originally thought to be suffering from elephantiasis. In 1971, Ashley Montagu suggested in his book The Elephant Man: A Study in Human Dignity that Merrick suffered from neurofibromatosis type I, a genetic disorder also known as von Recklinghausen's disease. This disease is still strongly associated with Merrick in the mind of the public; however, it was postulated in 1986 that Merrick actually suffered from Proteus syndrome (a condition which had been identified by Michael Cohen just seven years earlier).[2]Unlike neurofibromatosis, Proteus syndrome (named for the shape-shifting god Proteus) affects tissue other than nerves, and is a sporadic rather than familially transmitted disorder. In July 2003, Dr. Charis Eng announced that as a result of DNA tests on samples of Merrick's hair and bone, she had determined that Merrick certainly suffered Proteus syndrome, and may have had neurofibromatosis type I as well. As it stands, many people still mistakenly refer to his condition as elephantiasis.

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