Bone Physiology Flashcards

1
Q

______ is dense and used for support

A

Compact bone

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2
Q

____ or ____ forms a calcified lattice

A

spongy bone or trabecular bone

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3
Q

What is the primary responsibility of bone?

A

to develop and maintain mass and architecture sufficient to carry functional loads without fracture.

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4
Q

______: occurs when resorption precedes formation

A

re-modeling (structure present, then taken down, then remodeled)

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5
Q

4 stages of bone re-modeling

A

1)quiescence
osteoclasts: recruitment, differentiation, activation
2)resorption
osteoblasts: recruitment, proliferation
osteoclasts: apoptosis, removal
3)reversal
matrix synthesis
4)formation
mineralization

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6
Q

_______ are unique bone resorbing cells of the monocyte-macrophage lineage

A

osteoclasts

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7
Q

characteristics of osteoclasts:
nucleus - _______
activated by - ______

A

multinucleated

receptor activator of nf kappa b ligand (RANKL)

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8
Q

Osteoclasts:

polarization facilitates _____, _______, and _____

A

clear zone, ruffled border formation, and bone resorption

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9
Q

disease in which osteoclasts are unable to resorb bone. What is the shape seen on X-ray?

A

Osteopetrosis

erlenmeyer flask appearance

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10
Q

bone remodeling is accelerated with _______

A

age

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11
Q

Name some other scenarios in which osteoclasts would be more active than osteoblasts

A

low testosterone
low estrogen
low systemic calcium levels

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12
Q

osteoblasts come from what progenitor cell?

A

mesenchymal cells

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13
Q

mesenchymal cells can differentiate into which cells?

what is the determining factor?

A

chondrocytes, myoblasts, adipocytes, and tendon cells

TRANSCRIPTION FACTORS

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14
Q

osteoblasts make ______, express the ______ receptor, also produce ____ and ____ (ECM proteins),

A

type I collagen, EXPRESS PARATHYROID HORMONE RECEPTOR, osteocalcin and bone sialoprotein

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15
Q

osteoblast transcription factor: ______

A

Runx2, (Runx2 -/-mice don’t make bone)

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16
Q

______ have osteoblast phenotype

A

osteocytes

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17
Q

Sclerostin is made in _____, blocks _____, and inhibits _____.

A

osteocytes, Wnt signaling, bone formation.

18
Q

disease associated with sclerostin?

A

osteosclerosis (sclerostin always missing)

19
Q

_________ molecules are a fundamental control of bone remodeling.

A

Wnt signaling molecules

20
Q

Name two ways to increase bone formation.

A
  • ab to RANKL would decrease the availability of RANKL to bind osteoblasts and activate osteoclasts, and would increase bone mass.
  • Ab that inhibits sclerostin would unblock Wnt signaling and lead to increased bone formation.
21
Q

______ are the most abundant cell type in bone

A

osteocytes

22
Q

osteocytes are ______ in origin

A

mesenchymal

23
Q

bone formation inhibitor associated with osteocytes?

A

sclerostin

24
Q

sclerostin plays a role in both ____ and ____

A

bone modeling and bone remodeling

25
Name some diseases of altered calcium homeostasis and bone metabolism.
``` osteoporosis osteopetrosis osteosclerosis cancer diabetes, cardiovascular disease, treatment side-effects ```
26
decrease in _____ is associated with increased Fracture risk
bone mineral density (BMD)
27
mortality rate associated with hip fractures
24%
28
________ inhibit bone resorption by inhibiting farnesyl synthase and preventing formation of __________
bisphosphonates | ruffled border
29
bisphosphonates reverse _____ and decrease ____
bone loss | bone turnover
30
two treatments for osteoporosis?
bisphosphonates and blocking RANKL
31
Current treatment used to block RANKL?
Xgeva, used to block downstream differentiated products, blocking eventual formation of osteoclasts (WITHOUT INTERFERING WITH PROGENITOR CELL)
32
a bone disease that makes bones abnormally dense and prone to fracture. Associated with diminished OSTEOCLAST function. Characterized by skeletal fragility.
osteopetrosis
33
a bone disease of abnormal hardening of bone and an elevation in density. Associated with increased OSTEOBLAST function. Characterized by increased bone mass.
osteosclerosis
34
______ ______ is associated with hypercalcemia, nerve compression, bone pain, and fracture.
bone metastasis
35
bone metastasis is facilitated by the activity of ______
osteoclasts (intravasation, homing and survival, extravasation)
36
Therapeutic targets blocking steroid-dependent tumor cell proliferation
androgen and estrogens via aromatase inhibitors
37
treatments for cancer can cause ___ and ____
osteopenia and osteoporosis
38
how does type 2 diabetes increase risk of bone fracture?
- hyperglycemia and hypercalciuria lead to low bone turnover. - hyperinsulinemia, hyperglycemia, treatment with TZD, low vitamins (D) leads to lone bone quality. - concomitant meds, cataracts, peripheral neuropathy, retinopathy, ulcers, hypoglycemia, nocturia can all increase the risk of falls
39
correlation between cardiovascular disease and PTH?
increased risk of vascular disease over time with high levels of PTH
40
bone fractures are a major risk factor with significant morbidity and mortality with which age group?
ANY AGE GROUP!!!!
41
DISEASE: the skeleton plays a central role in _____, _____, and ____
disease development, response to treatment, and quality of life.