At a voltage-clamp step to

PHYSICS · Multi-part · Fermi University Physics · Biophysics & Medical Physics · Bioelectricity, the senses and the physics of the body · Bioelectricity, the senses and the physics of the body

Forces, Machines and Signals, Ch The nerve impulse

Problem

At a voltage-clamp step to 0 mV0\,\mathrm{mV}, the sodium activation gate (mm) of the Hodgkin-Huxley model has rate constants αm=4.1 ms−1\alpha_m = 4.1\,\mathrm{ms^{-1}} and βm=0.11 ms−1\beta_m = 0.11\,\mathrm{ms^{-1}}. ((a)) Find the steady-state activation m∞m_\infty and the relaxation time τm\tau_m at this voltage. ((b)) The potassium activation gate stepped to the same voltage has τn=1.65 ms\tau_n = 1.65\,\mathrm{ms}. State which gate responds faster and why this matters for the shape of the action potential.

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