Renal Phys Body Fluid Compartments Flashcards
What is the basic water composition of the body?
60-40-20 rule
60% of body weight = water
40% of body weight = ICF water = 2/3 of total water
20% of body weight = ECF water = 1/3 of total water
What are the two parts of ECF?
interstitial fluid = 3/4 of ECF
Plasma = 1/4 of ECF
What is the only fluid that can be directly acted on to control its volume and composition?
plasma
What is third spacing?
too much fluid shifts from blood vessels into nonfunctional area of cells = trapped btw tissues and organs = edema
What are the major ions of the extracellular fluid?
Na+
Cl-
HCO3-
Which type of ECF contains more protein anions?
plasma
What are the major ions of the ICF?
K+
Po43-
Protein anions
What are nonelectrolytes?
molecules that contain covalent bonds that prevent them from dissociating in sol’n
What is osmolarity vs. osmolality?
osmolarity = # of particles per L sol’n
osmolaLity = # of particles per Kg sol’n
How much of the blood is plasma? How much is RBCs?
plasma = 60%
RBCs = 40%
How would a loss of ECF affect total plasma protein? What about a gain?
loss of ECF –> gain of total plasma protein (concentration)
gain of ECF –> loss of total plasma protein
What is normal hematocrit for a male?
For a female?
- 4
- 36
How will changes in ECF volume affect hematocrit?
ECF volume loss –> increased hematocrit
ECF volume gain –> decreased hematocrit
How would ICF volume changes affect hematocrit?
ICF increase –> increased hematocrit (cells swell)
ICF decrease –> cells shrink –> decreased hematocrit
What marker is used to measure the volume of ECF?
inulin
What indicator is used to measure plasma volume?
albumin
What is the Gibbs-Donnan Effect?
presence of negatively charged proteins in cell that are impermeable to membrane –> causes both water and charges to want to come into cell
= both osmotic and electrochemical gradients generated
How does the body counteract the gibbs’donnan effect?
Na/K ATPase counteracts inward force –> pumps 3 Na out for every 2 K in
(PumpKin)
prevents excessive inward mvnt of water
What pressure relationships favor filtration?
Capillary hydrostatic pressure > capillary osmotic pressure
What pressure relationship favors absorption?
when capillary blood pressure/hydrostatic pressure falls below capillary osmotic pressure
When does edema become apparent?
when interstitial volume is increased by 2.5-3 L
need renal retention to actually see edema
What is pitting vs non-pitting edema due to?
non-pitting edema = swollen cells due to increased ICF
pitting edema = increased ECF
What is the starling eqn for net filtration?
K[(Pc - Pi) - (πc - πi)]
What is a hypertonic solution?
causes cells to shrink
NaCl concetration greater than 0.85%
What is a hypotonic solution?
causes cells to swell
NaCl concentration less than 0.85%
What is an isotonic solution?
NaCl concetration equal to 0.85% or 300 mOsm
cells stay happy
What is a crystalloid replacement?
contain organic or inorganic salts (saline)
do not cross plama membranes, but can go across capillary walls = stay in IF and blood
What is colloid replacement?
contains large molecules that don’t pass through capillary walls = stay in intravascular space and pull in more water to bloodstream
What is the eqn for plasm/serum osmolarity?
2(Na) + glucose/18 + BUN/2.8
What is the eqn for plasma osmolality?
2(plasma [Na+])
What is hypotonic/ hyponatremic dehydration?
Na leaves faster than H20 –> [Na] in ICF becomes greater than in ECF –> water will shift from ECF to cells
What is hypertonic/ hypernatremic dehydration?
H2O leaves faster than sodium –> [Na] is greater in ECF –> water leaves cells
serum osmolality and sodium levels will be increased
What is a volume contraction?
decrease in ECF –> decreased blood volume and BP
What is volume expansion?
increased ECF –> increased BP and edema
What is a darrow-yannet diagram?
used to study the effect of clinical conditions
osmolality = Y axis
volume = x axis
solid line = normal values
dashed lines = change in volume and osmolality
What is an iso-osmotic volume contraction?
What does it look like on darrow-yannet?
direct loss of ECF –> only see ECF volume loss, but no change in osmolality or ICF volume
What is a hyperosmotic volume contraction?
What does it look like on darrow-yannet?
decrease in ECF and ICF volumes
increase in body osmolality
What does a hypo-osmotic volume expansion look like?
gain of hypotonic fluid –> increased ECF and ICF, but decreased body osmolality
What does an isoosmotic volume expansion look like?
gain isotonic solution –> increased ECF
no change in ICF or osmolality
