Term
| free calcium is used for what processes: |
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Definition
- bone formation
- heart contraction
- muscle contraction
- neurotransmitter release
- blood clotting |
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Term
Explain this considering normal blood caclium is 10:
- total blood calcium of 13
- albumin is 1.5 times normal. |
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Definition
| Albumin is high, so more calcium is bound up, so total calcium is high, but free calcium is normal b/c had to increase free back up to normal |
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Term
| So when you have a high or low calcium, you must also check ___ to understand it. |
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Definition
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Term
| PTH is released when calcium levels are ___, and has what two main actions: |
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Definition
- low
- causes resorption of calcium from bone to blood
- causes reabsorption of calcium in kidneys |
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Term
| What system does PTH NOT act on? |
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Definition
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Term
| In the bone calcium is in the form of calciium phosphorous crystals. So when ___ causes release of calcium from bone, lots of ___ is also released. Thus, PTH also acts on the kidney to ___ phosphorous. |
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Definition
- PTH
- phosphorous
- excrete |
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Term
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Definition
- calcium and phosphorous resorption from bone to blood
- kidney reabsorption of calcium
- kidney excretion of phosphorous |
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Term
| So when PTH is high, phosphate tends to be ___. |
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Definition
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Term
| You can use ___ as a measure to determine if PTH is working. So ___ should be ___ if PTH is working. |
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Definition
- phosphate
- phosphate
- low |
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Term
| The enzyme in the kidney that makes vitamin D is inhibited by ___. So by causing the kidneys to ___ phosphate, ___ indirectly increases vitamin D synthesis and thus causes increased absorption of calcium in GI tract. |
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Definition
- phosphate
- excrete
- PTH |
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Term
| Cells in bone that move calcium work better if ___ is present. So PTH works better on bone when ___ ___ is present. |
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Definition
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Term
| What happens if you take too much vitamin D? |
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Definition
- vitamin D doesn't need PTH anymore, so it just starts demineralizing bone
- vitamin D induced rickets> lose strength of bone |
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Term
| Vitamin D is made from ___ in the ___. |
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Definition
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Term
| cholesterol ring in liver>> (sunlight)>> cholecalciferol (D3)>>(25 hydroxylase) >> 25-hydroxy-cholecalciferol aka calcidiol >>> kidney>> (1-hydroxylase) >> 1-25 Dihydroxycholecalciferol = active calcitriol> mostly to intestine, some to bone |
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Definition
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Term
| low calcium> increased PTH> increased calcium and phosphate resorption from bone> increased calcium reabsorption in kidneys and increased phosphate excretion in kidneys> increased vitamin D3 synthesis in kidneys> increased absorption of calcium via calcitonin in GI tract |
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Definition
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Term
| So without ___, you have high renal phosphate, so you don't make active vitamin D. |
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Definition
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Term
| So to make active form of vitamin D, what two things must you have? |
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Definition
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Term
| Explain hypocalcemia from low PTH: |
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Definition
| something wrong with parathyroid gland > low PTH> hypocalcemia> calcium resorption from bone> calcium secretion from kidneys> high phosphate so not much vitamin D> low absorption of calcium from GI tract> excreting calcium in urine and feces |
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Term
| Explain pseudoparathyroidism: |
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Definition
| - everything looks like hypocalcemia but sky high PTH b/c PTH receptors don't work> high PTH, low calcium b/c excreting it in feces and urine, high phosphate |
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Term
| Explain hypocalcemia from low vitamin D: |
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Definition
| low vitamin D> don't absorb much calcium in GI tract> low calcium> increased PTH> resorption of calcium from bone but not great without vitamin D> low phosphate b/c high PTH> fecal excretion of calcium, resorption of caclium in kidneys but it is not enough, phosphate excretion in kidneys |
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Term
| explain what Hypercalcemia from hyperparathyroid with parathyroid adenoma: |
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Definition
| - adenoma of parathyroid gland> elevated PTH> stimulates bone resorption> kidneys excrete phosphate and make vitamin D, lose net calcium even though you absorb some> bringing in a ton from bone and GI tract> lots of calcium so get kidney stones |
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Term
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Definition
| parathyroid related polypeptide, secreted by cancers, acts like PTH so it looks like hyperparathyroidism, but PTH measurement would be really low |
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Term
| Two causes of hypercalcemia: |
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Definition
- from tumor that secretes excess PTH
- from tumor that makes PTHrP which behaves like PTH, but PTH levels would actually be really low |
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Term
| Explain hypercalcemia caused by excess vitamin D consumption. |
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Definition
| - too much vitamin D> bone gets demantelized> high calcium and vitamin D inhibit PTH> lose lot of calcium in the kidney but retain the phosphate b/c low PTH |
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Term
| explain hypercalcemia caused by vitamin D like material. |
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Definition
| Tumors or diseases called granular mitosis diseases (TB)> produce vitamin D like material> hypercalcemia with low PTH |
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Term
| Sometimes cancers will manifest themselves via back pain b/c demineraliztion of bone b/c of vitamin D like material that’s breaking down bone via osteoclasts (testicualr or ovarian cancer) |
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Definition
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Term
| How does hypocalcemia affect your reflexes? |
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Definition
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