Solution-Rectangular current pulses into axons of two diff | Homework Help

You inject identical (subthreshold) rectangular current pulses into axons of two different neurons, one of which is shown in the upper illustration. The injection site is near position “a” for each cell and the resulting voltages are recorded at position a, b, and c, separated by 100 microns each. The illustration below shows superimposed voltage traces from all three sites for Neurons 1 and 2. Based on these data we can say that the axon of Neuron 1 has a ___.

1. a)  Larger length constant, larger time constant, and smaller membrane resistance than 2.
2. b)  Smaller length constant, smaller time constant, and smaller membrane resistance than 2.
3. c)  Larger length constant, a smaller time constant, and smaller membrane resistance than 2.
4. d)  Smaller length constant, a larger time constant, and larger membrane resistance than 2.
5. e)  Larger length constant, a smaller time constant, and larger membrane resistance than 2.

(Picture corresponding to #1 is attached)

1. Which of the following statements is FALSE? If all statements are true, pick e.
   1. a)  The repolarization phase of an action potential is a consequence of both an inactivation of Na channels and an opening of K channels.
   2. b)  The threshold of an action potential depends on the relative amount of current flowing through Na and K channels.
   3. c)  Opening chloride channels in a typical neuron would increase the ability of the neuron to fire action potentials.
   4. d)  The Nernst equation describes a situation in which there is no net current across the membrane for a particular ion, so if only one ion is permeable at rest, there is no need for ion pumps to maintain ion concentrations.
   5. e)  All of the above are true.