Chapter 4

Compare the role of myelin in vertebrates with that in nonvertebrates. Consider that the rate of nerve conduction observed in the mylinated axons of the penaeid shrimp is comparable to that observed in vertebrates (200 m/sec).

How does the delayed opening of \(\mathrm{K}^{+}\)channels lead to the repolarization stage of impulse propagation?

The synthetic compound tetroethylommonium (TEA) selectively blocks most types of gated \(\mathrm{K}^{+}\)channels, but it does not block the \(\mathrm{K}^{+}\)leak channels. Explain what happens to membrane potential after an action potential spike with TEA present, and why.