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28 Cards in this Set

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  • Back
  • 3rd side (hint)
functions of Ca in body
skeleton & teeth, intracellular mess, musc ctx, coag
distribution of Ca in body
99% in teeth/skel
storage in tissues
Ca concentration most tightly regulated at...
Plasma/ECF interchange
cytoplasm concentration goes up & down
ECF must be maintained w/o change
best blood test to indicate Ca status
free Ca (usually 50%)
factors affecting free calcium
alkylosis- lowers (more bound to proteins)
acidosis- raises (less bound to prots)
albumin doesn't, just changes total
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)
hormones involved in Ca regulation
vitamin D & PTH
(calcitonin is minor player)
role of PTH in Ca balance
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)
role of vit D in Ca balance
activated D increases intestinal absorption and bone resorption (release from stores)
Ca Receptor
in kidney, Thyroid & parathyroid
regulates Ca
sources of Vit D
synthesized in skin (activated to D3 by UV)
absorbed with fat in diet
(D2 is in food)
synthesis of Vitamin D
from dehydrocholesterol (in skin)
transport to liver (VitD binding protein)
25 hydroxylase
to kidney when needs activation
characteristics of 1,25 D
short half life
toxic (like A)- cause calcification of tissues
VDRE controls expression of over 200 genes
causes of D deficiency
decreased UV
exclusive breast feed
veg diet
fat malabsorp
renal dz (can't activate)
liver dz (can't make 25
meds affecting vit D
calcium absorption
active w/low intake
(more transporters at membrane w/activated D)
passive transfer (tight jctns) at high intake
location of Ca absorption
fastest in duodenum b/c pH low
most in lower SI b/c amount of time there
solubility of Ca
best in supplements w/lactate, acetate, gluconate, citrate, acrbonate
then whole milk
least with oxalate
Calcium changes during pregnancy & lactation
estrogen increases intestinal absorption
bone mineral density of mom decreases during lactation (3-5%) increases when stop
imbalance of Ca resorption & synthesis
defect in mineralization
Osteomalacia- if occurs during childhood get Rickets
causes of rickets
vit D def-
type I= defect in 1 hydroxylase
type II= defect in D receptor

low Ca in diet
causes of hypocalcemia
rarely diet
low PTH
renal fail
Vit D def
causes of hypercalcemia
hyper PTH (from an adenoma)
Vit D excess
best measurement of PTH
intact protein in serum
affect of magnesium deficiency on PTH
inhibits release of PTH
Calcium intake affects lipids...
low Ca:
increased synthesis of 1,25 D
encourages lipid synthesis
Vit D affect on muscles
increases # muscle fibers