Problem set: water and solute movement across membranes

27.

In the diagram below are two solutions (A and B) separated by a membrane permeable to water but not solutes. Use this as the starting condition for the questions below. (10 pts)

B.

459 osmoles

9 liters

A.

520 osmoles

10 liters

a. In this initial condition, what is the osmolarity of solution A?

In this initial condition, what is the osmolarity of solution B?

b.

If you compare osmolarities of solution A to B, solution A is _______________ to B.

c.

In which direction will water move between these compartments?

d.

After all osmosis has occurred, what will the osmolarity of compartment A be?

e.

How much total water has moved into or out of compartment A?

28.

A juvenile patient arrives in the hospital after a long soccer game with the following values initially (assuming you have a way to measure each):

Total body water volume = 30 liters

Solute amount in the total body = 9.6 osmoles

Solute amount in the extracellular fluid = 3.2 osmoles

Solute amount in the intracellular fluid = 6.4 osmoles

a. What is the patient’s initial intracellular osmolarity?

b. What is the patient’s initial intracellular fluid volume?

c. How much water would this patient need to ingest to return body osmolarity values to normal (300 mOsM)?

d. If this patient is given an IV solution of 0.9% NaCl + 5% glucose, how would his body osmolarity change? (circle your answer)

increaseno changedecrease

e. If this patient is given an IV solution of 0.9% NaCl how would his intracellular fluid volume change? (circle your answer)

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