Homework-04-solutions

Homework-04-solutions - BME 402 Homework 4 Due 11am Monday...

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BME 402 Homework 4 Due 11am Monday 3/5/06 Neural Cables Be able to derive the cable equation like we did in class using Kirchhoff’s current law. Know the definition of the space constant λ and the input resistance R in for an infinite uniform cable and how these depend on diameter, and know what the steady state voltage profile looks like in a uniform cable for various boundary conditions (i.e. if the cable terminates in a fatter or thinner cable or a closed end, or two or more daughter branches). Know the d 3/2 law for matched input conductances at branch points. Understand why the speed of voltage propagation in a cable depends more on R i than R m . Understand why myelin speeds the propagation of AP’s and why action potentials block when myelin is disturbed. Be able to briefly discuss at least one myelin-related disease. Synapses: Overview Be able to compare and contrast electrical synapses (gap junctions) and chemical synapses, in terms of where in the nervous system they occur, their approximate dimensions, their physical components (know the basic vocabulary), their transmission delays, their directionality, and their functional uses. In particular, be able to explain what advantages accrue to chemical synapses that justify their much greater complexity. Be able to name at least 8 neurotransmitters, and be able to say a couple of interesting/informative things about each (such as where they are found, whether excitatory or inhibitory or both, whether they are involved in direct or 2 nd messenger gated transmission or both, what diseases are associated with their imbalances, what drugs or blockers act on their receptors, etc.). Know what is meant by “reversal potential”, and what this corresponds to in an electric circuit representation, and what the reversal potentials typically are for excitatory and inhibitory synapses (and what ions are involved). Neuromuscular Junction Be able to draw the basic structure of the NMJ including the single axon (and know where the parent neuron lives), its multiple release sites on the endplate, as well as a cross sectional view of the pre- and post-synaptic terminals. Know some approximate numbers: how many vesicles are typically released, how many channels are typically activated, how large is the typical EPSP in the muscle fiber. Know what neurotransmitter is used, and what ions carry the synaptic current. Be able to draw what the synaptic response looks like under both current and voltage clamp including the approximate time course. Know several things that can go wrong with the NMJ, including the names of at least one toxin that blocks the ACh receptor, another that interferes with pre-synaptic release, and a drug that acts on acetylcholinesterase. Be able to desribe how the symptoms of at least one disease arise from dysfunction at the NMJ.
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This note was uploaded on 02/27/2008 for the course BME 402 taught by Professor Mel during the Spring '06 term at USC.

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Homework-04-solutions - BME 402 Homework 4 Due 11am Monday...

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