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23 Cards in this Set
- Front
- Back
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what is the structure of type I collagen?
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- triple-helical supercoil made up of 2 α1 chains and 1 α2 chain
- gly-pro-hypro |
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what is released when type I collagen is degraded
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- hydroxyproline
- indicator of bone resporption |
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what links collagen in bone and cartilage?
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- intramolecular and intermolecular (most critical) cross-links
- hydroxylysine w/ cartilage - lysine and hydroxylysine w/ bone |
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what do serum derived proteins do?
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- they are part of non-collagenous proteins of the bone
- acidic and bind to the mineral of bone - this can provide local []'s of serum-derived GF's like PDGF and IGF-1 |
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what are the 3 groups of non-collagenous proteins that are NOT serum derived, and where do they come from?
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- cell attachment and Ca binding proteins (Gla proteins)
- growth and diff proteins (TGF-B like BMPs, IGF-1) - AP, which initiated mineralization - they are secreted by blasts |
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what are the proteoglycans of bone?
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- both are GAGs
- chondratin sulfate - does early bone formation w/ blast pericellular environment - heparin sulfate - helps blast interactions |
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lipids in bone
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- TGs, FFAs, CHL, PL's
- may be involved in ossificication - b/c they can ind Ca |
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where does Ca from bone come from?
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- less than 1% from bone is available
- from lining of H canals and resorption cavities |
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scurvy
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- vitamin C deficiency
- prevents normal OH of proline and lysine, so decreased quantity and quality of collagen - New bone formation is prevented and older bone becomes brittle - Skin collagen affected too |
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what is the mineralization lag time
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5-10 days after osteoid is laid down
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Ehlers-Danlos syndrome
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- inherited collagen disorder, seven different types
- hyperextensible joints, hyperelastic skin - poor wound healing and easy bruising - due to delicate collagen fibers in multiple locations |
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what is nuclation in bone?
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- when the seed of hydroyapitate is deposited
- initiated by blast-derived matrix vessels from the |
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whats the deal w/ osteocytes?
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- they can make collagen, control mineralization, and respob bone
- they do too much resprotion in many diseases like hyperPT, pagets, or disuse osteoporosis - they are the 1o site for Ca exchange |
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MMP's
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- matrix metalloproteinases
- secreted by clast in resorption - dissolve the various parts of bone (substrate specific) |
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all about a BMU
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- takes 4 months
- the unit that forms in bone remodeling |
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what controls clast stem cells
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- from hematopoetic cells of BM (CFU-GM)
- IL-1 and 6 - TGF a and b |
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what controls blast stem cells
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from local CT mesenchyme or BM
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used to monitor bone resorption
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- osteocalin
- hydroxyproline (urine) - pyridinoline (urine) - more specific - deoxypyridinolin (urine) - most specific |
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what amount of Ca is transferred per day?
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- in most places, 200-500 mg
- BUT from serum to bone, 6g |
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parathyroid hormone
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- released when Ca is low
- for fine tuning - causes release of Ca from bone |
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1,25-D
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- for long term control
- stimulated intestinal Ca absorption |
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calcitonin
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- buffering system for Ca
- can act act to lower Ca, but not when is superhigh - controls for postprandial high Ca to keep PTH secreting |
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order of Ca removal from body
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- leaky dike
- then bone surfaces in contact w/ bone fluid - then, when PTH really high, activation of clasts that just take it randomly |
