Body Fluid Compartments Flashcards
Isosmotic volume contraction
Examples? Changes in volume of ECF and/or ICF? ECF Osmolarity?
Diarrhea, burn, vomiting
ECF volume decrease
No change in ICF volume or ECF osmolarity
Hyperosmotic volume contraction
Examples? Changes in volume of ECF and/or ICF? ECF Osmolarity?
Sweating, fever, diabetes insipidus
ECF volume decreases
ICF volume decreases
ECF Osmolarity increases
Hyposmotic volume contraction
Examples? Changes in volume of ECF and/or ICF? ECF Osmolarity?
Adrenal insufficiency
ECF volume decrease
ICF volume increase
ECF Osmolarity decrease
Isosmotic volume expansion
Examples? Changes in volume of ECF and/or ICF? ECF Osmolarity?
Infusion of isotonic NaCl
ECF volume increase
No change in ICF volume or ECF osmolarity
Hyperosmotic volume expansion
Examples? Changes in volume of ECF and/or ICF? ECF Osmolarity?
High NaCl intake
ECF volume increase
ICF volume decrease
ECF Osmolarity increase
Hyposmotic volume expansion
Examples? Changes in volume of ECF and/or ICF? ECF Osmolarity?
SIADH
ECF volume increase
ICF volume increase
ECF Osmolarity decrease
Normal fluid distribution including TBW, extracellular, and intracellular
TBW = 60% of our body weight (kg)
Extracellular compartments = 20% of our TBW
Intracellular = 40% of our TBW
What is the breakdown of extracellular compartments?
Extracellular = 20% of our TBW composed of:
75% interstitial fluid
25% plasma (which is 80% venous, 20% arterial)
________ = transcellular space considered an extracellular fluid compartment with negligible volume under normal conditions
Third space
Major cations/anions in intracellular vs. extracellular spaces
IC = K+ cations, protein anions
EC = Na+ cations, Cl- anions
Where are protein levels highest? What are the major proteins?
ICF and vascular compartments - albumin and globulins
Values of V(D) for plasma, all of ECF, TBW, and TBW+tissues
Drug only in plasma = 3 L
Drug in plasma + interstitial fluid (ECF) = 14 L
Drug in TBW = 40-45 L
Drug in TBW + tissues = greater than 45 L
What basic starling forces favor filtration?
Pc (hydrostatic pressure within lumen of capillary)
Pi(i) (oncotic pressure in interstitium)
Where is sodium the highest in the ECF
Vasculature, followed by interstitial fluid
What concentration can be used to quickly estimate plasma osmolarity?
Sodium
2[Na+]
Or:
2[Na+] + glucose/18 + urea/2.8
Normal osmolarity of plasma electrolytes
290 mOsm
What is the Gibbs Donnan effect
Na+ and K+ concentration is slightly higher than expected in the vascular space because the negative charge of proteins within vasculature attracts positively charged Na and K ions
RBC placed in isosmotic solution
No change
RBC placed in hyperosmotic solution
RBC shrivels
RBC placed in hyposmotic solution
RBC swells and bursts
What neurohumoral and effector mechanisms occur during disease like CHF which tend to act against our kidneys in the long run?
In heart failure, CO decreases and underfilled vasculature stimulates compensatory renal mechanisms to increase Na+ and water retention which restores perfusion pressure but exacerbates edema
Changes in ECF, ICF, and osmolality with Addison’s disease (hypoaldosteronism)
Hypoaldosteronism –> loss of sodium
Osmolarity in ECF decreases
ECF decreases
ICF increases
Changes in ECF, ICF, and osmolality in diabetic ketoacidosis
Osmolarity in ECF increases
ICF decreases
ECF decreases
A severe case of diarrhea would be characteristic of which of the following changes in body fluids?
A. Isosmotic volume expansion
B. Isosmotic volume contraction
C. Hyperosmotic volume contraction
D. Hyposmotic volume contraction
B. Isosmotic volume contraction
[ECF volume decreases, ICF volume and ECF osmolarity are unchanged]
Syndrome of inappropriate anti-diuretic hormone secretion results in which of the following changes in body fluids?
A. Isosmotic volume expansion B. Hyperosmotic volume expansion C. Hyperosmotic volume contraction D. Hyposmotic volume contraction E. Hyposmotic volume expansion
E. Hyposmotic volume expansion
[ECF volume increases, ICF volume increases, ECF osmolarity decreases]
