Bone Flashcards

1
Q

Composition of bone

A
cells: osetoblast/clast / cyte
osteoid
95% type 1 collagen
5%- groubd substance-proteoglycan
mineral crystalline hydroxyapetiteq
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2
Q

lengthening of bone vs widening

A

L: at epiphyseal late
W: bone matrix on outer shaft and resoprtion on inner part

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3
Q

what increases chondrocyte growth

A

IGF1
FGF2
TGF BETA

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4
Q

BMP?

A

Bone morphonegentic protein

induce hypertrophy and differentiation of chondrocytes

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5
Q

systemic hormones

A

thyroid an vitamin D: INDUCE HYPERTROPHY

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6
Q

Explain Bone remodeling

A
orgination of BMU
Osteoclast recruitment
resorption
osteoblast
osteoid
mineralization
Quiescence
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7
Q

Orgination of bmu

A

lining cells are activated by PTH , growth factors anf local cytokines

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8
Q

osteoclast recruitment

A

M-CSF induce RANK expression

RANK Ligand will bind but can be inhibited by OPG

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9
Q

OPG

A

Osteogrotegrin

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10
Q

bone remodeling : resorption .

A

Acid and digestive enzymes are secreted into sealed space.
Integrins, interleukins and vitamin A stimulate resorption.
Decreased estrogen delays apoptosis of osteoclasts.

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11
Q

bone remodeling: Osteoblast recruitment

A

attached to BMU by TGF Beta , BMP and IGF

cbfa-1 increases osteoblast

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12
Q

bone remodeling: Osteoid

A

Osteoid (bone matrix) formation

Osteoid is made by osteoblasts in layers

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13
Q

bone remodeling :mineralization

A

Mineralization is initiated when the osteoid reaches a thickness of approximately six Fm.

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14
Q

bone remodeling :Quiescence

A

G. Quiescence

As bone is completed osteoblasts are converted to osteocytes or lining cells and their metabolic rate declines.

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15
Q

osteoporosis

A

a disease characterized by low bone mass and microarchitectural deterioration of bone tissue, leading to enhanced bone fragility and a consequent increase in fracture risk

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16
Q

prinary vs secondary osteoprosis

A

primary: not linked to another cause

secondary : is. cushings, hyoerthyroidism, marfaans syndrome, scurvy drug induced disorders etc

17
Q

ways to measure bone resorption

A

Urinary calcium, hydroxyproline, and collagen cross-links have been used to measure bone resorption

18
Q

PTH role in bone remodeling

A

stimulate RANKL and supress OPG

19
Q

Estrogen role in bone remodeling

A

increase OPG and inhibit RANKL