What is in the electrolyte panel?
Na, K, Cl, total CO2
Electrolytes - what are the cations and anions?
- cations: Na, K, Ca, Mg
- anions: Cl, HCO3, PO4, lactate
TBW - % of mass, and breakdown in body "areas"
- 55%(F)-60%(M) of body mass (declines w/ age, obesity)
- Intracellular fluid (ICF) = 66% TBW
- Extracellular fluid (ECF) = 33% TBW
- Interstitial fluid = 25% TBW (ECF)
- Plasma = 8% TWB (ECF)
Why is plasma only 93% water by volume?
- Protein (necessary for colloid osmotic pressure) and lipids occupy volume
- Ions/solutes DO NOT occupy volume
What is the target ECF osmolality? What regulates it?
- 275-295 mOsm/kg
- Hypothalmic osmoreceptors make big changes from small changes (1-2%)