exam 2: regulation of plasma calcium and phosphate Flashcards
85% of the body’s PHOSPHATE is stored in _______, 14-15% in _____ and less than 1% in the _____
bones
cells
EC fluid
only .1% of total body calcium is in the ________. 1% is in _____ and ____ and the rest is store in _________
EC fluid
1% in cells
rest in bones
too low of calcium=
neuronal hyper-excitability (tetany)
too high of calcium=
neuronal depresion
control points for calcium and phosphate:
- absorption
- excretion
- temporary storage
control points for calcium and phosphate: (regulation)
1. absorption=
2. excretion=
3. temporary storage=
- absorption= via intestines
- excretion= via urine (both ca and phos) (feces ca only)
- temporary storage= via bones (hydroxyapatite)
carpal spasm due to
HYPOcalcemia
3 principle hormones that regulate plasma calcium and phosphate:
- parathyroid hormone (PTH)
- calcitriol
- calcitonin
PTH:
increases Ca
decreases phosphate
calcitriol:
increases ca
increases phosphate
calcitonin:
decreases ca
decreases PTH
what hormone is the primary hormone that enhances intestinal absorption of calcium and it also causes absorption of phosphate
calcitriol (vitamin D3)
releases Ca from bone, enhances renal reabsorption of calcium (kindeys), increases intestinal absorption of calcium (indirectly)= increase vitamin D production
PTH
in addition to PTH, bone resoprtion is stimulated by
cortisol and T3
how does PTH indirectly increase intestinal absorption of calcium
increasing vitamin D production
what two things stimulate bone matrix RESORPTION which INCREASEs plasma calcium
vitamin D3 aka calcitrol and parathyroid hormone PTH
excess vitamin D’s main effect is ___ ______ of calcium and phosphate
gut absorption
build bone matrix:
break down bone matrix:
build: osteoblasts
break down: osteoclasts
what binds to osteoclasts and activates them?
increase of these produced by osteoblasts and it lets them break down the hydroxyatite to increase plasma calcium and phosphate
RANKL
occurs when imbalance between bone formation and resoprtion
osteoporosis
risk factors for osteoporisis
vitamin D deficiency
inadequate calcium intake
estrogen deficiency
smoking
alcohol
reduced activity
lot of other things that activate osteoblasts that break down calcium (bone breakdown) break down hydroxyapatite
corticosteriods (cortisol)
prolactin
vitamin D3
calcitonin stimulates bone matrix ________ and inhibits ________= ____ in plasma calcium
deposition
inhibits osteoclasts
decrease in plasma calcium