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38 Cards in this Set
- Front
- Back
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what are the 5 main functions of bone?
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1) Support and shape
2) Protection 3) Allow movement 4) Calcium and phosphate homeostasis 5) Blood cell production |
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When do osteoblasts become osteocytes?
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When they become encased in the bone itself
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The 3 main components that make up bone are?
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1) Collagen (type I)
2) Hydroxyapatite 3) Ground Substance = proteoglycans |
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What provides the tensile strength to our bones?
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Collagen
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What do osteoblasts secrete apart from collagen to synthesize bone?
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- Calcium
- Phosphate - Hydroxyl ion |
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What is the formula for hydroxyapatite?
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Ca10(PO4)6(OH)2
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What protein serves as a precipitation point between collagen and hydroxyapatite?
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Osteonectin
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What is the function of osteocalcin?
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promotes the binding of hydroxyapatite to osteonectin
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What feature allows osteocytes to secrete calcium into the serum from within the core of bone?
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syncitial processes
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Osteocytic Osteolysis functions to?
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provide body with large amounts of calcium from its repository
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What 2 proteins found in the urine would indicate increased bone resorption in the body?
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hydroxyproline
hydroxylysine |
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Osteoclasts derive from what large, multi-nucleated cells to ultimately reside on surface of bone?
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monocyte macrophage precursors
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What membrane proteins mediate attachment of osteoclasts to periosteum?
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integrins
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Osteoclastic and Osteoblastic activity can be simultaneously going on at what regional site of the bone?
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Osteon
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What % of calcium is replaced in growing young adults?
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100%
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What chemicals/hormones inhibit osteoblastic activity?
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Cortisol
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What are the effects of the following on bone?
-Insulin -Estrogen -Calcitonin? |
Stimulate osteoblasts --> increase bone depostion ---> decrease in serum Calcium
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What are the effects of the following on bone?
-PTH -Cortisol -Thyroid hormone |
Stimulate osteoclasts ---> decrease in bone ----> increase in serum Calcium
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Prostaglandins
IL-1 and IL-6 TNF all serve what function in regards to bone? |
stimulate osteoclasts to resorb bone
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Estrogen
Androgens Transforming growth factor Calcitonin Interferon NO all serve to do what for bone? |
inhibit osteoclastic activity
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what is the turning point for women having reached menopause?
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~ 50yo
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makes up 80% of bone in the body
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Corticol Bone
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What type of bone has a higher turnover rate per year?
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Spongy/Trabecullar Bone
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What is the % calcium turnover for adults?
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18%/year
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Concentric Type I collagen rings surrounding a Haversian canal containing blood vessels is as a whole called?
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Osteon
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How much calcium might one find in a 70 kg male or female?
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1000g
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the total plasma calcium concentration is
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10mg/dl
2.5mmol/L 1.2mmol/L ionized Ca++ |
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Vitamin D3 functions to do what in concern of bone?
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stimulate both osteoblasts and osteoclasts
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What is considered the 'hypocalcemic hormones?
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Calcitonin
Vitamin D3 |
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Where is Calcitonin stored and released?
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Parafollicular 'C' cells of Thyroid gland
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What is Vitamin D3 called?
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Cholecalciferol
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What is the active form of Cholecalciferol?
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1,25 - dihydroxycholecalciferol : after processing in liver and kidney
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Vitamin D3 requires what to be activated to cholecalciferol?
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sunlight
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What is the major blood form of Vitamin D3?
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calcitriol
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_____ is required for absorption of Vit D in the ______
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bile salts
ileum |
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What is considered the 'hypercalcemic hormone'?
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PTH released from the chief cells of the parathyroid glands
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PTH inhibits what for the secretion of Vitamin D3?
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Kidney
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PTH decreases the excretion of ____ thus increasing its concentration in the plasma?
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phosphate
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