1. Inner hair cell of a bullfrog The data at right represent behaviour of stereocilia of an auditory hair cell, obtained by “displacement clamp” tests, whereby their force, f, was measured at the displacements shown. What mechanical properties are evident? What kinetic property is evident? When applied force is near zero, what displacement will never be naturally observed? f Martin et al Proc. Natl Acad Sci, 97: 12026, 2000

2. What kind of experimental measurements are being done on the RBC shown at right? Describe all the components you recognize.

3. The records at right are the displacement histories of a 40 nm bead in an elastic material. Assuming <x2> = 1225 nm2 can you find the spring constant of the material? (if so, what is it?)

4. Ion [ion] in (mM/L) [ion] out K+ 400 20 Na+ 50 440 Cl+ 52 560 Referring to the table, compute the Equilibrium potentials for the ions distributed across the squid axon. Membrane potential is –60 mV. If the total membrane conductance is 5 ohms-1 /m2, compute the conductance for each ion (remember gK =25 gNa=2gCl at rest). What is the initial flux of Na just after the pumps have stopped? What is the charge p.u. time p.u. length, in axon 1 mm in diameter? Ion [ion] in (mM/L) [ion] out K+ 400 20 Na+ 50 440 Cl+ 52 560