Osmosis and Osmotic Pressure Flashcards
What is the average intracellular/extracellular concentrations of Sodium?
14 mEq/L and 140mEq/L
What is the average intracellular/extracellular concentrations of Potassium?
120 mEq/L and 4 mEq/L
What is the average intracellular/extracellular concentrations of Chloride?
10 mEq/L and 105 mEq/L
What is the average intracellular/extracellular concentrations of Calcium?
0.0001 mEq/L and 2.5 mEq/L
What is the average intracellular/extracellular concentrations of Proteins?
Variable and 7g/dL
What is the average osmolarity of the intracellular/extracellular environments?
They both have the same osmolarity of 290 mOsm.
How do you calculate osmolarity?
Osmolarity = (the number of particles the solute dissociates into when placed in solution) x (the molar concentration of the solute)
What is the significance of a reflection coefficient of 0 vs 1?
If 0, solute is completely permeable to the membrane, osmotic pressure is 0, and solute will diffuse across the membrane.
If 1, solute cannot cross the membrane, osmotic pressure is high, and osmosis will occur.
What is the normal range of osmolarity in the intracellular/extracellular environments?
270 - 300mOsm
What is normal saline and what is the significance of its concentration of solute?
An IV solution of 0.9% NaCl. Used because it is isosmotic to RBCs.
What is the equation to calculate plasma osmolality when given lab values?
Estimated Osmolality = (2 x [Na]) + ([glucose]/18) + ([BUN]/2.8)
Describe the difference between osmolarity and tonicity.
Tonicity is independent of the osmolarity and depends solely on what actually happens to the when an RBC it is placed in that solution. If the reflection coefficient is close to 1, then osmolarity and tonicity will match.
