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44 terms
Terms | Definitions |
|---|---|
 3 roles of calcium (what it helps with) | contraction of muscles, clotting of blood, impulse conduction of heart and NS |
| most important calcium-transporting organs (what do they exachange calcium with) | bone, kidneys, and intestines (the blood) |
| two main types of bones | cortical bone & trabecular |
| cortical bone (what it comprises, physical characteristics, where is it found) | makes up 80% of bone mass, high calcified and dense, found mainly in the appendicular skeleton (arms and legs) |
| trabecular bone (what it composes, where is it found) | makes up 80% of surface of bone, found in marrow-containing areas (spine and metaphyses) |
| 4 bone cell types | osteoprogenitor, osteoblasts, osteocytes, osteoclasts |
| osteoprogenitor cells (precursors for, what are they like, where are they located) | mesenchymal precursors, highly proliferative, located in periosteum and endosteum |
| osteoblasts (produce, what are they like) | matrix producing cells, they are plump and basophilic |
| what makes up 90% of cell mass of bone | osteocytes |
| what are the bone resorbers | osteoclasts |
| periosteum | covers bone |
| osteoblasts synthesize and release | collagen |
| collagen forms | an extracellular matrix around the osteoblasts |
| what leads to ossification | calcium and phosphate binding to the collagen matrix and precipitating |
| what may enhance bone mineral precipitation | conditions of local alkanization resulting from osteoblastic activity |
| after calcification of the collagen matrix, the | embedded cells are osteocytes |
| demineralization (what causes it, with what acids) | bone resorption causes by osteoclasts that release acid phosphatase and hyaluronic acid |
| what happens after osteoclasts remove bone | osteoblasts enter the site and secrete osteoid, a matrix that is calcified into new bone |
| bone remodeling | process by which bone resorption by osteoclasts is balanced by bone formation of the osteoblasts |
| bone catabolic effect is | bone resorption by osteoclasts |
| bone anabolic effect is | bone formation by osteoblasts |
| how calcium is divided up in the blood | 50% is ionized and 50% is protein bound |
| main protein that binds to blood calcium | albumin |
| 3 main hormones that regulate calcium | parathyroid hormone, vitamin D, calcitonin |
| target organs of PTH (3) | bone, gut, kidney |
| PTH affect on blood calcium | increases blood calcium levels |
| what happens if you remove the parathyroid gland? | plasma calcium with drop - death |
| antagonist to PTH | calcitonin |
| give PTH in a continuous dose - | breaks down bone (downregulate collagen transcription) |
| give PTH in intermittent doses - | builds bone (upregulate collagen transcription) |
| cacein | a dye that marks newly formed bone |
| Osteoproenitors and osteoblasts are targets for | anabolic PTH action |
| PTH receptor is coupled to | cAMP and Ca2+/IP3 pathway |
| cAMP pathway is primary pathway for | stimulation of osteoblast genes |
| PTH mediates both | bone resporption and formation |
| how does the Vitamin D receptor work | as a heterodimer with RXR (type II) |
| VDR | vitamin D receptor |
| VDR is mostly what | nuclear |
| where is calcitonin produced | by the clear cells of the thyroid gland |
| main action of calcitonin | lowers serum Ca2+ levels |
| what happens to 3 hormone levels immediately after feeding | gastrin and calcitonin levels increase, while calcium levels stay constant |
| rickets | vitamin D deficiency in children - bone malformations |
| osteomalacia | vitamin D deficiency in adults - softening of bones |
| most common metabolic bone disease | osteoporosis - net loss of bone mass |
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