Body Fluid Compartments Flashcards
compartments of the extracellular fluid
plasma and interstitial fluid
major cation of the ECF, plasma and interstitial fluid
Sodium
major cation of the ICF
potassiuim
major anion of ECF (plasma and interstitial)
Cl
Major anion of the ICF
phosophates, protein
membranes are impermeable to ______, so they normally do not impact osmolarity. However, they do exert _________
impermeable to proteins
but exert oncotic (colloid osmotic) pressure: pressure generated by large molecules (like proteins) in solution that are impermeable to membranes
ECF can be measured using these indicators
22Na+, l-iothalamate, thiosulfate
INULIN
TBW can be measured using these indicators
3H2O, 2H2O, antipyrine
ICF cannot be measured using an indicator but it can be calculated by
TBW - ECF = ICF
Plasma volume can be measured with these indicators
l-albumin, Evans blue dye
interstitial fluid cannot be measured using an indicator, but can be calculated by
ECF - plasma = ISF
albumin can be used to measure plasma volume because
it should not cross plasma membranes
two compartments that arent measured directly
ICF and ISF
Na and K concentration is slightly _____ than expected in the vascular space due to what effect
slightly higher than expected due to Gibbs-donnan effect - negative charge of proteins within the vasculature attracting positively charged Na and K ions
= 290 mOsm
ECF osmolality is driven by
1) Na and Cl
2) Na vasculature > Na interstitial > Na ICF due to action of NA-K ATPase pump
ICF osmolality is driven by
K
Equation for plasma osmolality
= 2(Na) + Glucose/18 + urea/2.8
ECF and ICF are highly permeable to ______ but not permeable to most ______
water
electrolytes
Pc stands for the
hydrostatic pressure within the lumen of a capillary
force promoting movement of fluid from lumen to interstitium
factors that will increase Pc
increased arterial pressure
Increased venous pressure
decreased precapillary resistance
Increased postcapillary resistance
Pi stands for
hydrostatic pressure within the interstitium
promotes fluid in the lumen to remain in the lumen
Pic stands for
oncotic (colloid osmotic) pressure within the capillary
discourages movement of fluid out of the lumen
Pi i stands for
oncotic (colloid osmotic) pressure within the interstitium
Promotes movement of fluid out of the lumen
osmolality of the _____ controls volume of the _____
ECF osmolality controls ICF volume
All water and solutes must pass through the ____ first
ECF
causes of edema
abnormal leakage of fluid from plasma to the interstitial spaces across the capillaires
or
failure of lymphatic to return fluid from the interstitium back to the blood
congestive heart failure scenario
movement of fluid from intravascular space to interstitial space decreases ECV
Udnerfilled vasculature stimulates compensatory response renal mechanisms
Na and water retention
Restores perfusion pressure but exacerbates edema
primary renal disease scenario
inappropriate renal retention of sodium and water overfills vascular tree
- volume expanison, elevates blood pressure
- increases hydrostatic pressure while decreasing plasma oncotic pressure
