Hey! I have some neuronbio questions! HELP is greatly appreciated.
1. What can you say about Neuron 1 and 2? (see attachment 1)
a. Larger length constant, larger time constant, and smaller membrane resistance than 2.
b. Smaller length constant, smaller time constant, and smaller membrane resistance than 2.
c. Larger length constant, a smaller time constant, and smaller membrane resistance than 2.
d. Smaller length constant, a larger time constant, and larger membrane resistance than 2.
e. Larger length constant, a smaller time constant, and larger membrane resistance than 2.
2.The curves below are from two voltage clamp experiments with squid axon with a resting potential of -75 mV in normal seawater. Capacitance currents have been omitted. In the lower trace the clamp voltage was stepped from the resting potential to -20 at time 0. In the upper trace the clamp voltage was stepped to +65. The currents at X, Y, and Z are, respectively (see attachment 2)
a. inward sodium; inward potassium; outward potassium
b. outward sodium; outward potassium; inward sodium
c. inward potassium; inward sodium; outward sodium
d. outward potassium; outward potassium; inward sodium
e. inward sodium; outward potassium; outward sodium
3. The microelectrode inserted into the axon at point X below records a propagating action potential that reaches a peak height of 120 mV above the resting potential. What will the peak amplitude be when the spike arrives at point Y? [The space constant of the neuron is 3 mm.] (see attachment 3)
a) 0 mV – it will not arrive at Y
b) 30mV
c) 60mV
d) 120 mV
e) more than 120 mV
(is the ans b?)
4. The five action potentials shown below are all recorded from the same nerve cell axon in response to the identical current pulse shown below. The action potential in the curve labeled “normal” is typical for this cell. The four other traces are action potentials under the influence of 4 different drugs which alter the time constants, Tm (Sodium channel activation gate), Th (the sodium channel inactivation gate), and Tn, the (potassium channel activation gate). Each drug affects one gate only, either by increasing or decreasing . Which curve shows the effect of the drug that increases Tm, but has no effect on any other time constant? (see last attachment)
a) a
b) b
c) c
d) d
(is the ans C?)
thank you so much!!!
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