1. Inner hair cell of a bullfrog

1
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
2.

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

3
3.

• The records at right are the displacement
  histories of a 40 nm bead in an elastic material.
  Assuming
• ltx2gt 1225 nm2 can you find the spring constant
  of the material? (if so, what is it?)

4
4.

• 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 gNa2gCl 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 (mM/L)
K 400 20
Na 50 440
Cl 52 560