Limb and bone development Flashcards

1
Q

What is the primary ossification center?

A

Diaphysis

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2
Q

What is the secondary ossification center?

A

Epiphysis

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3
Q

What are the two types of ossification?

A

Endochondral ossification - cartilaginous
Intramembranous - fibrous membrane

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4
Q

What is appositional bone growth?

A

New chondroblast add new layers increasing diameter

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5
Q

What is interstitial bone growth?

A

Chondrocytes lay down more matrix in cartilage increasing length - epiphyseal plates

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6
Q

What are the stages of intramembranous ossification?

A

From mesenchyme - condense
Vascularize and differentiate into osteoblasts
Collagen fibers lay
Early osteoblast cluster - center for ossification

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7
Q

What are the stages of calcification?

A

Osteoblasts secrete osteoid
Cells surrounded by matrix form lacunae
Osteoblast secrete alkaline phosphatase with calcifies osteoid

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8
Q

What is cancellous bone?

A

Inner bone layer

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9
Q

What is compact bone?

A

Outer bone layer

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10
Q

What are the steps of endochondral ossification?

A

Mesenchyme condenses and differentiates into chondroblasts with form cartilage. Chondrocyte matures, calcifies, and dies
Growth to form periosteum
Mesenchymal cells to osteoprogenitors to osteoblasts
Form endosteum

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11
Q

What are the 5 zones of the epiphyseal plate?

A

Reserve cartilage
Cell proliferation
Cell maturation and hypertrophy
Calcifying cartilage
Provisional ossification

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12
Q

What are the types of epiphysis?

A

Pressure
Traction
Atavistic
Aberrant

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13
Q

What are the arteries to bone?

A

Nutrient
Periosteal
Metaphysial
Epiphysial

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14
Q

What are the nonartery vessels and nerves that go to bone?

A

Nutrient vein
Lymphatic vessels in periosteum
Periosteal nerves

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15
Q

What causes achondroplasia?

A

Early ossification of epiphyseal plate

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16
Q

What are the 4 stages of limb development?

A

Bud
Paddle
Plate
Rotation

17
Q

What forms a limb bud?

A

Outer ectodermal cap
Inner mesodermal core

18
Q

What is the role of apical ectodermal ridge?

A

Digit formation and elongation of limb segments

19
Q

What maintains apical ectodermal ridge?

A

Zone of polarizing activity mediated by SHH

20
Q

What occurs in the absence of apical ectodermal ridge?

A

No limb development

21
Q

What is responsible for the positioning of limbs during development?

A

HOX genes

22
Q

What is necessary to initiate limb development?

A

fgf signalling

23
Q

When does amelia occur?

A

Suppression of limb bud in early wk 4?

24
Q

When does meromelia occur?

A

Disturbance in differentiation in wk 5

25
Q

What is brachydactyly and its cause?

A

Shortness of digits
Autosomal dominant

26
Q

What multipotent stem cells are derived by somites?

A

Sclerotome
Myotome
Dermatome

27
Q

What is derived by somatic lateral mesoderm?

A

Sternum, limbs, and girdles

28
Q

What is derived by sclerotome of paraxial mesoderm?

A

Vertebrae and ribs