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22 Cards in this Set
- Front
- Back
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What type of Ca is biologically active and hormonally regulated?
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ionized Ca++
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if you have an excess of phosphate, what does this do to Ca?
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it will couple with Ca, so it will not be available for use
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where does the majority of calcium get reabsorbed?
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Proximal tubule
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Where is the hormonal control of reabsorption of Ca occur?
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at the distal convoluted tubule and collecting duct
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where does the majority of phosphate get reabsorbed?
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prox tubule
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What are the rapid effects of increased PTH? 2
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increased renal Ca reabsorption
osteocytic osteolysis |
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What is the slow effect of increased PTH?
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increased osteoclastic bone resorption
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increased synth of 1,25 vit D does what?
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increases intestinal Ca absorption
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Effect of PTH
& Vitamin D on Kidney Ca++ uptake? |
PTH increases the Ca 2+ channels in the distal tubule
Vit d increases the number of Calcium binding proteins that can shuttle them to be pumped back into the body |
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what is osteocytic osteolysis? rapid or slow?
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osteoclasts will take up calcium from the bone, it is tranferred to osteoclasts and then pumps it to extracellular space
this is a rapid response to PTH |
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PTH effects on Bone? 3 mechs
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No receptor on osteoclast
Receptors on osteoblast: indirect effect binds to osteoblast and increases M-CSF and RANK ligand these work on osteoclast precursors to make them into osteoclasts finally it decreases the negative effect of OPG (which would inhibit osteoclast precursor cells, but you block it) |
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what 3 areas does Vit D increase Ca uptake in an intestinal cell?
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1) brush border, helps bring it in
2)Ca binding protein 3) Ca 2+ ATPase to pump into the body |
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Effect of PTH on Kidney Phosphate Uptake?
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targets the removal of phosphate channels (destroys them) at the proximal tubule
in essence doesn't let you bring it back it this prevents phosphate from binding up free Ca |
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elevated PTH can cause what with your urine? 2
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hypercalciuria
hyperphospaturia |
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alkalosis will lead to increase or decrease in renal absorption of Ca?
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increase
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acidosis will lead to increase or decrease in renal absorption of Ca?
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decrease
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Loop diuretics will have what effect on Ca?
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it will increase Ca 2+ excretion
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Thiazide diuretics will have what effect on Ca?
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Thiazide diuretics may reduce Ca++ excretion most likely
due to increased PT reabsorption in response to volume depletion |
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Amiloride will do what to Ca?
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Amiloride increases Ca++ reabsorption and therefore decreases excretion)
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What cells have Ca binding receptors?
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Chief Cells
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An increase/decrease in [Ca] results in:
• less binding to receptor and relief of inhibition on exocytosis of PTH • increased synthesis of PTH • in the long term, proliferation of parathyroid cells |
decrease in [Ca]
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(+) 1 α hydroxylase
What does this do to PTH? |
Feedback inhibition of PTH
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