Lab 2: Osmosis and Hemolysis

Question 1

Describe the property of a solution that “osmolarity” quantifies.

Question 2

Understand how to calculate the osmolarity of solutions. List which molecular properties of the solutes are important to consider when making these calculations (i.e. NaCl vs. urea).

Question 3

Explain the two mechanisms by which water can move across plasma membranes.

Question 4

Know the typical value of intracellular osmolarity of human cells.

Question 5

Explain what you need to consider to determine if a solute is penetrating or nonpenetrating solute.

Question 6

Describe the characteristics of isoosmotic and isotonic solutions.

Question 7

Explain how you would determine if a solution is hyperosmotic, hypoosmotic, hypertonic, and hypotonic (relative to intracellular fluid).

Question 8

Explain how an isosmotic solution is not necessarily an isotonic solution. Consider what would happen to RBCs if they were placed in an isosmotic solution of penetrating vs. non-penetrating solutes.

Question 9

Predict what would happen to the volume of red blood cells if they were placed in a 1400 mOSM solution of
NaCl. Predict what would happen to the volume of RBCs if they were placed in a solution containing 700
mOSM of NaCl plus 700 mOSM of urea.

Question 10

Explain how the presence of approximately 150 mM NaCl (saline) can prevent osmotic swelling of red blood
cells in a solution that also contains some penetrating solute, such as urea.