L3 Body Fluids Flashcards
Distribution of Body Water
Total body water (TBW)
TBW = ICF + ISF + plasma
60-40-20 rule (% distribution)
TBW=60% body weight
ICF=40% body weight
ECF=20% body weight
How does water content correlate to body fat stores?
Inversely
Total body water =
0.7LBM + 0.1AT
Lean body mass (kg) Adipose tissue (kg)
If you don’t know LBM..
TBW= 0.6(weight kg)
At equilibrium all body water compartments have
The same osmolarity
It’s estimated from plasma osmolarity
Estimating plasma osmolarity equation
Osmolarity =
(2Na+)+ (glucose/18) + (BUN/2.8)
BUN= blood urea nitrogen
Capillary endothelium and most cell membranes are
Permeable to water
Plasma, interstitial fluid, and ICF have
Same osmolarity at equilibrium
To maintain equality
Water shifts between compartments
Electrolytes (Na+)
Do not cross cell membranes
Confined to ECF
Any loss or gain of water and/or electrolytes must initially occur where?
ECF
What are three things that can be measured that will give information about current hydration status of a patient?
Total body water
Total plasma protein
Hematocrit
Hematocrit
Percentage of plasma that is taken up by red blood cells
=height RBCs/total height
Changes in ECF causes what changes in hematocrit?
Dilution
Concentration
Changes in ICF cause RBCs to?
Swell or shrink
Changes in both ECF and ICF have what effect on hematocrit?
Additive and cancelling effects
What happens when you gain an isotonic fluid?
Isosmotic volume expansion
What happens when you lose an isotonic solution?
Isosmotic volume contraction
What happens when you gain a hypotonic solution?
Hypotonic volume expansion
What happens when you lose a hypotonic solution?
Hyperosmotic volume contraction
What happens when you gain sodium?
Hyperosmotic volume expansion
What happens when you lose sodium?
Hyposmotic volume contraction
What happens when you infuse isotonic glucose?
Hypotonic volume expansion
Body fluid shifts that cause volume contraction?
Diarrhea
Water deprivation
Aldosterone insufficiency
Body fluid shifts that cause volume expansion?
Infusion of isotonic NaCl
Higher NaCl intake
Pure water intake
Isosmotic means
No change in osmolarity of ECF
Hyperosmotic means
Increase in osmolarity of ECF
Hyposmotic means
Decrease in osmolarity of ECF
