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Memorize this‌ Renal Physiology Percent of total body weight that is Total Body Water (TBW)
60%
TBW is highest in
newborns and adult males
TBW is lowest in
adult females and adults with large amounts of adipose tissue
ICF comprises how much of TBW
2/3
Major cations of ICF
K+ and Mg2+
Major anions of ICF
protein and organic phosphates
ECF comprises how much of TBW
1/3
ECF is composed of
interstitial fluid and plasma
Major cation of ECF
Na+
Major anions of ECF
Cl- and HCO3-
How much of ECF is plasma?
1/4
How much of ECF is interstitial fluid?
3/4
An ultrafiltrate of plasma (has little protein)
interstitial fluid, bowman space
Steady state Osmolarities of ECF and ICF
Equal (about 295 mOsm/Kg water)
How equality of Concentration between compartments is achieved?
Water shifts (first response). Volume compartments change. Increase in ECF volume; decrease in hematocrit Decrease in ECF volume; increase in hematocrit Increase in ECF volume, ECF Osmolarity, serum Na+ conc.; decrease in ICF volume, Hct decreased
Isomotic volume expansion Isomotic volume contraction Hyperosmotic volume expansion