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8 Cards in this Set
- Front
- Back
Explain distribution of Ca++ in the body:
Explain distirbution of phosphate: |
99% in bone
1% intracellular 0.1% extracellular - plasma In plasma, 41% bound to proteins, so 59% available - 50% free, 9% bound to anions 85% in bones, 14% IC, 1% in ECF. plasma |
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ratio of Ca++ to PO4 in plasma:
Explain PTH synthesis and secretions: Effect of increased Ca++, ciruclating PO4, Vitamin D on PTH levels: |
5:3 - serum Ca++ ~9.4, PO4 ~4
pre-propeptide --> proPTH --> PTH continuously secreted with pulsatile surges; cleared in kidney, liver Ca++ - PTH destruction --> lowered serum Ca++ PO4 - increases PTH Vitamin D - decreases PTH |
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PTH effect on bones, kidney:
Effect on Vitamin D: |
bones - increases osteoblast activity, mobilizes Ca++ from bone
kidney - DCT - more Ca++, decreases PO4 absorption; PCT - decreased PO4 absorption activates - facilitates diffusion of Ca++ across GI membranes |
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Explain role of PTHrP:
Explain steps of Vitamin D synthesis: Where is PTH required for D synthesis? |
produced by most tissues, binds to PTH receptor, malignancies can increase PTH-type action, increased serum Ca++
D2/D3 precursors --> liver converts to another D3 --> modified D3 --> kidneys --> Vitamin D (calcitriol) D3 activation in kidneys to D |
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Action of Vitamin D:
Explain regulation of calcitonin: effects of calcitonin: |
increases Ca++/PO4 absorption/resorption
enhances PTH action, inhibits production Ca++, gastrin, intestinal hormones stimulate release destroyed by kidneys, liver opposite of PTH (decreased bone, kidney resorption, decreased serum [Ca++] |
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Composition of bone:
Explain bone formation: Osteoblast stimulators: What inhibits osteoclasts? |
70% Ca++, PO4
30% matrix - collagen OPG cells activate --> blasts, clasts, crystals resorbed by clasts, blasts make collagen matrix, Ca++/PO4 crystalizes GH, PTH, IGF, T3/T4, PGE2, load calcitonin, PGE2, estrogen |
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Effect of hypothyroid on blasts, clasts:
Effects of primary hyperPTH and hypercalcemia on body: Normal reflex response to chronic hypocalcemia, like in Vitamin D deficiency: |
decreased stimulation - decreased bone resorption, plasma Ca++
weakness, neural depression, short QT, kidney stones secondary hyperPTH |
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How does hyperPTH cause rickets?
Effect of Vitamin D deficiency: Causes of osteoporosis: |
increased blast/clast activity, extensive bone remodeling
decreased serum [Ca], [PO4], bone mass, rickets/osteomalacia, immobility, decreased A-, Ca++, Vit C, decreased estrogen, agin |