Problem Set 1-Equilibrium Potentials
Problem Set 1-Equilibrium Potentials
Problem Set 1-Equilibrium Potentials
1 a. (1 pt) Calculate the value of the diffusion coefficient for a solute that diffuses 0.3 cm in 20
seconds.
b. (1 pt) List the factors that determine the magnitude of the diffusion coefficient.
2. (2 pts) A smooth muscle cell has the following ionic concentrations inside and outside the
cell:
Inside Outside
+
Na 15 mM 150 mM
Cl- 40 mM 155 mM
The measured membrane potential = -65 mV (inside negative relative to the outside of the
cell). Note that R = 8.3 J/K mol, temperature = 37 oC and F = 96,500 C/mol.
b. What is the magnitude of the driving force for Na+ and Cl- movement?
3. (2 pts) A skeletal muscle cell has the following ionic concentrations inside and outside the
cell:
Inside Outside
+
Na 10 mM 120 mM
K+ 100 mM 2 mM
Cl- 5 mM 125 mM
The membrane potential = -75 mV (R = 8.3 J/K mol, T = 37 oC and F = 96,500 C/mol).
a. What are the equilibrium potentials for Na+, K+ and Cl- under these conditions?
b. Which ions are moving if any and in what direction?
c. What is the magnitude of the driving force for Na+, K+ and Cl- movement?
Scott M. O’Grady ANSC/PHSL 5700-PHSL 4700 Cell Physiology Problem Set 1
4. (2 pts) An epithelial cell is bathed in saline solution that contains 140 mM NaCl and the
membrane is permeable to Cl-. The intracellular Cl- concentration is 5 mM. The measured
membrane potential is -60 mV. Note that R = 8.3 J/K mol, temperature = 37 oC and F =
96,500 C/mol.
b. What would the intracellular Cl- concentration be if Cl- was at equilibrium at the
measured membrane potential of this cell?
5. (2 pts) A skeletal muscle cell is bathed in a saline solution that contains 2 mM CaCl2 and the
membrane is permeable to Ca2+. The intracellular Ca2+ concentration is 250 nM. The
measured membrane potential is -70 mV. Note that R = 8.3 J/K mol, temperature = 37 oC and
F = 96,500 C/mol.