Body Fluids CIS Flashcards
total body water
around 42L total
broken to ICF and ECF
ECF is plasma and interstitial fluid
plasma is venous and arterial
effective circulating volume
arterial
independent of ECF volume, plasma volume, and cardiac output
transcellular fluid
3rd fluid compartment
CSF, synovial, etc.
Vd
volume of distribution of drug
- apparent volume of body fluid in which total dose of drug is distributed at same concentration in plasma
- useful in calculating doses
Vd < 3L
only in plasma
Vd = 14L
drug in plasma and interstitial
Vd > 45L
drug widely distributed and bound in body tissues
body fluid compartments?
intake and output balanced
intracellular?
potassium and phosphate
also proteins and magnesium slightly larger
extracellular?
sodium, chloride, and bicarbonate
what remains relatively stable between extra and intra compartments?
total mOsm/L
-in osmotic equilibrium
more positive ions in plasma
because they can complex with negatively charged albumin
aka donnan effect**
albumin
higher in ICF and plasma
lower in interstitial fluid
proteins?
do not move across moembrane
-don’t impact osmolarity but do exert oncotic pressure
malnourishment?
not enough albumin in vessels to hold in water
water goes to peritoneal cavity (distended abdomen)
measure of body fluid compartment volumes
total body water, ECF, and plasma volume can be measured directly by dilution of injected radioactive substances or dyes
ICF then calculated by TBW - ECF
interstitial can be calculated ECF - plasma volume
plasma volume and hematocrit known?
TBV = plasma / 1 - hematocrit
osmolarity in ECF = ?
osmolarity of ICF
why is Na and K concentration slightly higher in vascular space?
donnan effect
-negative charge of proteins within vasculature attracts positively charged ions
balance in ECF?
between interstitial and intravascular
Na+ and osmolarity normally balanced
osmolarity established
in ECF due to presence of Na and Cl
disruption of pump activity?
ex/ hypoxia
increased ICF Na
water follows Na and cell swells
intracellular osmolarity
established by presence of K+