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NMSP Exam 2 > Bones, Joints And Soft Tissue Pt. 1 > Flashcards

Bones, Joints And Soft Tissue Pt. 1 Flashcards

1
Q

What is bone matrix?

A

The extracellular component of bone; consists of osteoid (organic component), mineral component and inorganic (hardness due to hydroxyapatide)

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2
Q

What is osteoid?

A

Made of type I collagen with small amount of glycosaminoglycans and other proteins

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3
Q

Which protein is present in osteoid?

A

Osteopontin (aka osteocalcin) produced by osteblasts; functions in bone formation, mineralization and Ca homeosatsis; marker for osteblastic activity

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4
Q

What are the 2 histological forms of bone?

A

Woven and lamellar

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5
Q

What is woven bone?

A

Produced rapidly during retal development and fracture repair; haphazard arrangement of collagen (less structural integrity); abnormal in adults but not specific for any bone disease

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6
Q

What is lamellar bone?

A

Slow production, parallel collagen, stronger than woven

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7
Q

What is the function of osteoblasts?

A

Surface of matrix; synthesize, transport and assemble matrix; regulates mineralization

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8
Q

What are osteocytes?

A

Inactive osteoblasts with decreased cytoplasm; contol Ca and phosphate levels; direct mechanical forces (mechanotransduction) translates them into biological activity

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9
Q

What are osteoclasts?

A

Multinucleated macrophages derived from circulating monocytes; function in bone resorption

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10
Q

What are the two types of bone development?

A

Endochondral and intramembranous ossifcation

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11
Q

What is endochondral ossification?

A

Occurs in long bones; cartilage mold = analgen, central medullary canal created by chondroblasts; osteoblasts deposit cortex beneath periosteum of diaphysis —> radial growth (primary center of ossificaiton); deposits of new bone at the bottom of growth plates (epiphyses) —> longitudinal growth (secondary centers of ossifcation)

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12
Q

What is intramembranous ossifcation?

A

Occurs in flat bones; mesenchyme directly ossified by osteoblasts, no cartilage analgen; appositional growth (direct deposit of new bone on pre-existing surface)

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13
Q

When is peak bone mass achieved?

A

In early adulthood after cessation of skeletal growth; 4th decade: resorption >formation —> decreased skeletal mass

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14
Q

What is the function of RANK during bone homeostasis and remodeling?

A

Receptor activator for NFkB on osteoclast precursors; when stimulated by RANKL, activates TF NFkB (essential for generation and survival of osteoclasts); allows for breakdown of bone

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15
Q

RANKL is expressed on which cell type?

A

Osteoblasts and marrow stromal cells

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16
Q

What is the function of osteoprotegerin (OPG) in bone homeostasis and remodeling?

A

OPG decoy receptor made by osteoblasts; can bind RANKL and prevent its interaction with RANK; builds bone

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17
Q

Which systemic factors promote osteoclast differentiation and bone turnover?

A

PTH, IL-1, and glucocorticoids

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18
Q

Which systemic factors block osteoclast differentiaton or activity by promoting OPG expression (factors that favor bone deposition)?

A

Bone morphogenic proteins (vitamin D) and sex hormones (estrogen, testosterone)

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19
Q

What is the function of WNT proteins in bone homeostasis?

A

WNT proteins produced by OPG cells bind to LRP5 and 6 receptors on osteoblasts thus triggering activation of beta-catenin and production of OPG

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20
Q

What inhibits the WNT/B-catenin pathway?

A

Sclerostin (produced by osteocytes) which suppresses bone formation

21
Q

The balance between net bone formation and resorption is modulated by what?

A

RANK and WNT

22
Q

What is the function of M-CSF in bone homeostasis?

A

M-CSF receptor on osteoclast precurose stimulates tyrosine kinase cascade that is crucial for generation of osteoclasts

23
Q

Which genes are affected in brachydactyly types D and E?

A

HOXD13

24
Q

What is the clincal phenotype seen with brachydactyly types D and E?

A

Short, broad terminal phalanges of first digits

25
Q

Which genes are affected in cleidocranial dysplasia?

A

RUNX2

26
Q

What is the clincal phenotype seen with celidocranial dysplasia?

A

Abnormal clavicles, Wormian bones, supernumeray teeth

27
Q

Which gene is affected in achondroplasia?

A

FGFR3

28
Q

What is the clinical phenotype seen with achondroplasia?

A

Short stature, rhizomelic shortening of limbs, frontal bossing, midface deficiency

29
Q

What gene is affected in thanatophoric dysplasia?

A

FGFR3

30
Q

What is the clinical phenotype seen with thanatophoric dysplasia?

A

Severe limb shortening and bowing, frontal bossing, depressed nasal bridge

31
Q

What gene is affected in achondrogenesis type 2 and what is the clincal phenotype?

A

COL2A1; short trunk

32
Q

Which gene is affected in osteoporosis with RTA?

A

CA2

33
Q

What is the clinical phenotype seen with osteopetrosis with RTA?

A

Increased bone density, fragility and RTA

34
Q

What are Wormian bones?

A

Extra bones within cranial sutures

35
Q

What is osteopetrosis?

A

Aka marble bone disease; decreased bone resorption due to deficient osteoclastic development/function —> diffuse, symmetrical skeletal sclerosis

36
Q

Most AR forms of osteopetrosis are caused by mutations in which gene?

A

TCIRG1 which encodes a subunit of the osteoclast vacuolar H-ATPase that is also necessary for acidification of the resorption pit

37
Q

What is osteopenia?

A

Decreased bone mass 1-2.5 SD below the mean of peak bone mass

38
Q

Once maximal skeletal mass is attained, what occurs with every resorption and formation cyccle?

A

Small deficits in bone formation accrues

39
Q

How does an estrogen deficiency affect bone?

A

Decreased estrogen —> increases both resorption and formation but formation < resorption leading to a high turnover rate; also leads to increased cytoknes (IL-6, TNF and IL-1) which increases RANKL —> decreased OPG —> osteoclast recruitment and activity

40
Q

What is von Recklinghausen disease of bone?

A

Increased bone cell activity, peritrabecular fibrosis and cystic brown tumors is hallmark of severe hyperparathyroidism = generalized osteitis fibrosis cystica

41
Q

What is a simple fracture?

A

Overlying skin intact

42
Q

What is a compound fracture?

A

Bone communicates with the skin surface (protrudes thru skin)

43
Q

What is a comminuted fracture?

A

Bone is fragmented (several pieces)

44
Q

What is a displaced fracture?

A

Ends of the bone at the fracture site are not aligned

45
Q

What is a stress fracture?

A

Slowly developing fracture that follows a period of increased physical activity in which the bone is subjected to repetitive loads

46
Q

What is a greenstick fracture?

A

Extending only partially through the bone, common in infants when bones are soft (looks like broken stick)

47
Q

What is a pathologic fracture?

A

Involving bone weakened by an underlying diseaes process, such as a tumor

48
Q

What can predispose someone to osteonecrosis?

A

Alcohol abuse, bisphosphonate therapy, CT disease, chronic pancreatitis, Gaucher disease, pregnancy, radiation therapy, sickle cell crisis, tumors and dysbarism (decompression sickness)

49
Q

What is sclerosing osteomyelitis of Garre?

A

Type of chronic osteomyelitis; Occurs in the jaw and associated with extensive new bone formation that obscures much of the underlying osseous structure

NMSP Exam 2 (4 decks)

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