intro to regulation of K, Ca, P, Mg balance DSA Flashcards
how much potassium is intracellular vs extracellular
98% intracellular
80% muscle
20% other cells
2% extracellular (3.5 - 5.0 mEq/L)
what is hypokalemia defined as
what is hyperkalemia defined as
> ~5.2 mEq/L
>10=lethal
what can cause pseudohyperkalemia
lysing of rbc’s during blood draw
what does hypokalemia do to resting membrane potential of normal cells
decreases it (hyperpolarizes or makes it more negative)
what does hyperkalemia do to resting membrane potential of normal cells
increases it (polarizes or makes it more positive)
what does hypokalemia do to resting membrane potential of cardiac cells
how does this look on an EKG
increases it (polarizes or makes it more positive)
low t-wave
what does hyperkalemia do to resting membrane potential of cardiac cells
how does this look on an EKG
decreases it (hyperpolarizes or makes it more negative)
high peaked t-wave
normal dietary intake of Ca
~1000mg/day
absorption best if split <500mg each dose
3 places Ca can enter circulation from
resorption from kidney
resorption from bone
ingestion (diet)
what enzyme is needed for absorption of Ca from GI and resorption from bone
Calcitriol
bone also needs PTH
what enzyme is needed for the formation of bone
calcitonin
what are the effects of hypocalcemia on muscle cells
increases excitability (lowers threshold potential)
what are the effects of hypercalcemia on muscle cells
decreases excitability (raises threshold potential)
major storage of phosphate in the body
bone 85%
cells 14%
serum 1%
