Fluid Distribution and Movement Flashcards
total body water
60% of total body weight in kg
what is fluid
water + solute
intracellular fluid
water inside of cells
- 2/3 of total body water
- separated by cell membrane from ECF
- regulated exchange
extracellular fluid
water outside of cells
- 1/3 of total body water
- interstitial, intravascular, and transcellular fluid
interstitial fluid
fluid within tissues
- 3/4 of ECFV
- separated by capillary endothelium from IVF
intravascular fluid
fluid within vessels
- 1/4 of ECFV
transcellular fluid
fluid within specialized compartments
does the ratio of fluid distribution in each compartment change at homeostasis
NO - constant ratios
does NOT depend on fluid volume
milliequivalence
content of a solute
mEq = millimoles x valence
1 mM CaCl2 =
- 1 mM Ca x 1 valence = 1 mM Ca
- 1 mM Cl2 x 2 valence = 2 mM Cl
does solute concentration OR ionic strength differ in each fluid compartment
solute concentration
compartments have the SAME ionic strength
different solute concentration allows for fluid flow
osmolarity
number of moles of solute per liter of solvent (mol/L)
- considers VOLUME
osmolality
number of moles of solute per kg of solvent (mol/kg)
- considers MASS
are osmolarity and osmolality equal in biology
YES - can be considered the same because 1 L of water = 1 kg of water
what is the osmolarity of plasma in healthy animals
300 mOsm/L
iso-osmotic
within 10% of 300 mOsm/L
(270-330 mOsm/L)
hyperosmotic
> 330 mOsm/L
hypo-osmotic
<270 mOsm/L
osmotic pressure
the pressure needed to STOP osmosis (flow of water from high to low concentration)
what does osmotic pressure depend on
NUMBER of molecules
osmole
osmosis caused by a mole of a substance
1 mOsm = 1 mEq
tonicity
effective osmolarity; creates osmotic gradients
ONLY measures effective osmoles
effective osmoles
can NOT freely move across membranes
- exerts osmotic effects (causes water to move)
- excluded from ICFV
Na, Cl, proteins, glucose
ineffective osmoles
can freely move across membranes
- does NOT exert osmotic effects (doesn’t cause water to move)
Urea, ethanol, lipid-soluble
what type of solutes does osmolarity measure
effective AND ineffective solutes