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28 Cards in this Set
- Front
- Back
- 3rd side (hint)
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functions of Ca in body
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skeleton & teeth, intracellular mess, musc ctx, coag
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distribution of Ca in body
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99% in teeth/skel
plasma/ECF storage in tissues |
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Ca concentration most tightly regulated at...
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Plasma/ECF interchange
cytoplasm concentration goes up & down ECF must be maintained w/o change |
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best blood test to indicate Ca status
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free Ca (usually 50%)
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factors affecting free calcium
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alkylosis- lowers (more bound to proteins)
acidosis- raises (less bound to prots) albumin doesn't, just changes total |
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calcium balance
how much is required where does it go/come in |
1000 mg in via diet
1000 mg out via colon (800mg) & kidney (200mg) |
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hormones involved in Ca regulation
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vitamin D & PTH
(calcitonin is minor player) |
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role of PTH in Ca balance
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PT senses low Ca level
releases PTH PTH causes rls Ca & PO3 from bone PTH causes prod/secretion of 1,25 D from kidney & increased reabsorp of Ca (not PO3) |
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role of vit D in Ca balance
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activated D increases intestinal absorption and bone resorption (release from stores)
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Ca Receptor
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in kidney, Thyroid & parathyroid
regulates Ca |
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sources of Vit D
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synthesized in skin (activated to D3 by UV)
absorbed with fat in diet (D2 is in food) |
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synthesis of Vitamin D
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from dehydrocholesterol (in skin)
transport to liver (VitD binding protein) 25 hydroxylase to kidney when needs activation |
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characteristics of 1,25 D
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short half life
toxic (like A)- cause calcification of tissues VDRE controls expression of over 200 genes |
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causes of D deficiency
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decreased UV
exclusive breast feed veg diet fat malabsorp renal dz (can't activate) liver dz (can't make 25 dilantin |
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meds affecting vit D
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dilantin
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calcium absorption
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active w/low intake
(more transporters at membrane w/activated D) passive transfer (tight jctns) at high intake |
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location of Ca absorption
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fastest in duodenum b/c pH low
most in lower SI b/c amount of time there |
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solubility of Ca
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best in supplements w/lactate, acetate, gluconate, citrate, acrbonate
then whole milk least with oxalate |
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Calcium changes during pregnancy & lactation
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estrogen increases intestinal absorption
bone mineral density of mom decreases during lactation (3-5%) increases when stop |
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imbalance of Ca resorption & synthesis
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osteoporosis
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defect in mineralization
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Osteomalacia- if occurs during childhood get Rickets
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causes of rickets
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vit D def-
type I= defect in 1 hydroxylase type II= defect in D receptor low Ca in diet |
3
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causes of hypocalcemia
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rarely diet
low PTH renal fail Vit D def hypomagnesium |
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causes of hypercalcemia
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hyper PTH (from an adenoma)
Vit D excess |
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best measurement of PTH
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intact protein in serum
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affect of magnesium deficiency on PTH
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inhibits release of PTH
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Calcium intake affects lipids...
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low Ca:
increased synthesis of 1,25 D encourages lipid synthesis |
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Vit D affect on muscles
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increases # muscle fibers
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