Problem set: water and solute movement across membranes
In the diagram below are ECF and ICF compartments separated by a membrane permeable to water and to Ca++. Use this as the starting condition for the questions below. (24 pts)
What is the initial osmolarity in the ECF before any CaCl2 solution is added?
What are the two fluid compartments that make up the ECF (extracellular fluid)?
One liter of a 15% calcium chloride solution will be added to the ECF. What is the osmolarity of the CaCl2 solution before it is added? (molecular weight of Ca= 40.1, Cl = 35.5) (CaCl2 has a disassociation constant of 3)
After the CaCl2 solution is added, how does the osmolarity of the body (ECF and ICF) change? circle your answer:
osmolarity decreasesno change osmolarity increases
The Ca2+ ion in the ECF diffuses through an open ion channel into the ICF but the Cl- ions cannot move into the ICF. Which compartment, therefore, has a higher concentration of non-penetrating solutes after the addition of the CaCl2 solution (before water or solutes move)?
Circle your answer for which way net water movement will be after the CaCl2 addition:
into ECFno net water movementinto ICF
Based on your answer directly above, what is the tonicity of the CaCl2 solution?
Circle your answers below to show how body osmolarity changes (increase, no change or decrease) and which way water moves when each IV fluid is added to the body.
0.9% NaCl (normal saline)N/C into ECF N/C into ICF
0.45% NaClN/C into ECF N/C into ICF
5% glucose in 0.45% NaClN/C into ECF N/C into ICF