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45 Cards in this Set
- Front
- Back
List 5 organic compnents of the bone.
Describe each. |
Osteoid - unmineralized bone
Osteoprogenitor cells - pluripotential mesenchymal stem cells; give rise to osteoblasts Osteoblasts - matrix synthesis and transport arrangement Osteocytes - controls Ca/Phosphorus level; detects mechanical forces and translate into biological activity Osteoclasts - bone resorption |
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List the function and cell of origin of osteoblast.
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From Osteoprogenitor cell
Function - matrix synthesis, transport arrangement |
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List the function and cell of origin of osteoclast.
List 3 stimulators and 1 inhibitor of osteoclast. |
from hematopoietic progenitor cell
function - bone resorption stimulators: cytokines, GFs, and RANK ligand. Inhibitor: osteoprotegerin (OPG) |
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List the function and cell of origin of osteocyte.
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Originate from osteoblast (trapped osteoblast in the canalicular network)
function - involved in mechanotransduction; translates mechanical forces into biological activity |
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What is mechanotransduction?
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detect mechanical forces and translates into biological activity
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What is Howship lacunae?
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scallop resorption pits made by acidification, enzymatic digestion via osteoclasts
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What is basic multicellular unit of the bone?
What cells are included in the unit? |
functional unit of the bone involved in modeling (initial growth) and remodeling (skeletal maintenance).
osteocytes, osteoblasts, osteoclasts. |
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Compare and contrast woven bone vs lamellar bone.
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Woven bone - random weave of bone
in fetal skeleton and growth plates in diseased or repairing adult bone lamellar bone - in orderly layers normal bone of adult stronger than woven bone has cement lines |
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List 4 steps in bone development.
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1. Condensation of primitive mesenchyme (homeobox genes)
2. Differentiation of chondrocytes and osteoblasts 3. Ossification (endochondral and intramembranous) 4. Enlargement: appositional growth. |
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What is the role of homeobox genes?
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condensation of primitive mesenchyme during embryonic period.
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Label this bone
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A. Diaphysis
B. Metaphysis C. Epiphysis D. Growth plates |
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what is osteopenia?
What is osteoporosis? |
Osteopenia - decreased bone mass
Osteoporosis - atrophy of bone tissue |
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Compare and contrast dysotoses from dysplasia
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Dysotoses - localized problem; problem with migration of mesenchymal cells or formation of condensations
Dyplasia - abnormal organization of cells; affects skeletal tissue globally |
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What is craniorachischisis?
General etiology? |
failure of closure of spinal column and skull.
Defects in nuclear proteins and transcription factors |
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Achondroplasia.
What is it? Etiology/pathophysiology? Results in? Inheritance pattern? Morphological changes? |
Most common growth plate disorder
Defect in paracrine growth signaling --> reduced physial chondrocyte proliferation results in dwarfism Morphological changes: narrow plate with reduced proliferating cartilage; transverse bars of bone sealing off plate |
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Mucopolysaccridoses
Cause? Results in? Morphological changes? |
Decreased degradation of MPSs (mucopolysaccharides) --> deposition in the physis
results in short stature and malformed bones Morphological changes in the physis: widened plate with stored MPS in chondrocytes; transverse bars of bone sealing off plate |
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Osteogenesis imperfecta
Synonym? Etiology? morphology? clinical presentations? (include extraosseous involvement) |
Synonym: brittle bone disease
Etiology: mutations in genes for type I collagen (mainly AD) Basic abnormality: osteopenia: extreme skeletal fragility Extraosseous involvement: a) Joints, skin, teeth b) Eyes: “blue sclerae” c) Ears: abnormal bone conduction |
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Osteopetrosis
Synonym? Pathogenesis? clinical presentations? |
Synonym: marble bone disease
Pathogenesis: decrease osteoclast formation or function --> decreased bone resorption --> diffuse skeletal sclerosis (stonelike but brittle) Clinical presentations: fractures, bony overgrowth ( can lead to anemia, infections, and CN compression), elongated metaphysis in femur (Erlenmeyrflask deformity) |
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What is the definition of osteoporosis?
List 3 primary etiologies of osteoporosis. LIst a few secondary etiologies of osteoporosis. |
Osteoporosis: atrophy of bone tissue; BMD ≥ 2.5 SDs below that of a normal young adult.
3 primary etologies 1. postmenopause 2. senile 3. idiopathic secondary etilogies 1. exogenous corticosteroids 2. Endocrine disorders (e.g. Cushing's) 3. Chronic renal disease, neoplasia, GI disorders. etc. |
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Describe the pathogenesis behind postmenopausal osteoporosis.
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Decreased serum estrogen --> increased IL-1,6 and TNF levels --> Increased RANK/RANKL and decreased OPG --> increased osteoclast activity
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List 6 ways aging can cause osteoporosis.
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1. decreased replicative activity of osteoprogenitor cells.
2. decreased synthetic activity of osteoblasts 3. decreased biologic activity of matrix-bound GFs. 4. reduced physical activity 5. decreased intestinal Ca absorption. 6. decreased renal synthesis of active form of Vit D. |
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List clinical manifestation of osteoporosis.
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1. loss of height.
2. kyphoscoliosis 3. pulmonary complications |
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70 YO Caucasian male with pain in the proximal femur. Histology reveals mosaic pattern of lamellar bone.
What disease? |
Osteitis deformans (Paget's disease)
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List 3 phases of osteitis deforman.
Is there a net gain or loss of bone mass? |
1. osteolytic phase
2. mixed osteoclastic-osteoblastic phase 3. ostoesclerotic phase Net gain in bone mass |
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What is the pathogenesis of Paget's disease?
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RANK signaling --> increased NF-kB activation --> increased
osteoclast recruitment, activity Hyperresponsiveness of affected osteoclasts to: vitamin D and RANKL |
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List 2 main complications of Paget's disease.
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Leontiasis ossea - enlarged facial bones, coarsening of features
Platybasia - invagination of base of skull, due to increased weight of skull |
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Causes in rickets in children and osteomalcia in adults.
Cause? Pathogenesis? |
Vitamin D deficiency.
Decreased bone Ca --> defective osteoid mineralization --> cartilage fails to calcify --> chondrocytes fail to mature and disintegrate |
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Causes scurvy.
cause? Pathogenesis? |
Vitamin C deficiency
↓ normally cross-linked collagen --> defective osteoid formation: normal woven bone is not formed; calcified cartilage resorbed by osteoclasts |
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Hypercalcemia, dissecitng osteitis, and brown tumor.
Cause? (primary or secondary?) what is dissecting osteitis? What is brown tumor? |
Primary hyperPTH
Dissecting osteitis - osteoclasts tunnel into and dissect centrally along the length of trabeculae, creating the appearance of railroad tracks Brown tumor - multicystic mass and hemosiderin deposition in the bone. |
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Describe the pathogenesis in renal osteodystrophy.
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renal dysfunction --> phosphate retention and decreased vit D --> hypocalcemia --> secondary hyperPTH
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What is von Recklinghausen disease of bone?
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A complication of hyperPTH.
Symptoms: hemorrhage --> cystic degeneration |
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List 8 types of bone fracture.
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1. complete and incomplete (greenstick)
2. closed (simple) and compound 3. comminuted 4. dispalced 5. pathologic 6. stress |
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What is bone callus? Procallus?
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Bone callus - extra-ossification around the healing area.
Bone procallus - granulation tissue in the bone during the healing process. |
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Describe the process of bone repair.
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1. Inflammation: granulation tissue ingrowth and release of GFs and interleukins (activate osteoprogenitor cells to differentiate into osteoblasts and chondrocytes)
2. Repair: callus formation 3. Remodeling: Woven bone --> lamellar bone |
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What is delayed union?
What factors can cause non-union? |
Delayed union of the fractured bone occurs in fracture complications.
They can be caused by: 1. age (older) 2. Vascular insufficiency 3. malnutrition 4. misalignment. 5. excessive mobility. |
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What causes non-union of the bone in bone fracture?
What happens to the non-union bone? |
Excessive mobility --> non-union
the bone forms: 1. nonssified fibrocartilagenous tissue 2. pseudoarthrosis: joint-like tissue with synoviocytes 3. infection might occur. |
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What is osteonecrosis?
Common predisposing factor? Common locations? Complication? |
Osteonecrosis is ischemic necrosis of bone or marrow
predisposing factors: tenuous blood supply. Commonly occurs in the femoral head. other sites include humeral head, distal femur, talus, carpal bones. Complication: arthritis |
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What is Caisson's disease?
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Thrombus/embolus in the vascular supply near femoral or humeral head causing osteonecrosis.
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What is creeping substitution?
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It is a process of osteoclasts resorbing the necrotic trabeculae during the healing process. However, those that remain act as scaffolding for the deposition of new bone.
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What is osteomyelitis?
List 3 common organisms involved in osteomyelitis. List 3 pathogenesis. |
Osteomyelitis - inflammation of bone or marrow
3 organisms recovered 1. Staph aureus 2. Gram neg enterics 3. Salmonella Pathogenesis 1. direct implantation 2. hematogenous spread 3. extension from contiguous site |
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What is Sequestrum?
How does this occur? |
Sequestrum is necrotic bone embedded in pus.
process: suppuration --> pressure on vessels --> ischemia --> sequestrum |
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What is involucrum?
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Reactive sheath of periosteal new bone around sequestrum in response to extracortical, subperiosteal dissection of pus
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What is Brodie abscess?
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bone abscess walled off by reactive bone; usually in the metaphysis
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List 3 complications of osteomyelitis.
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1. dissemination: septicemia, endocartidis.
2. septic arthritis 3. chronic osteomeylitis |
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What is Pott's disease?
Location? Complications |
A complication of TB (TB osteomyelitis)
Occurs in the spine, esp. T11 Complications 1. compression fracture --> kyphosis 2. neurological deficits 3. TB arthritis 4. REactive systemic amyloidosis |