1. What is the role of glial cells in the brain and other parts of the nervous system?

2. The resting potential of a neuron is approximately –70 mV inside compared with outside the cell. How is the resting potential maintained in animal cells?

3. Name the three phases of an action potential. Describe for each the underlying molecular basis and the ion involved. Why is the term voltage-gated channel applied to Na⁺ channels involved in the generation of an action potential?

4. Explain how the crystal structures of potassium ion channels suggest the way in which the voltage-sensing domains interact with other parts of the proteins to open and close the ion channels. How does this structure-function relationship apply to other voltage-gated ion channels?

5. Explain why the strength of an action potential doesn’t decrease as it travels down an axon.

6. Explain why the membrane potential does not continue to increase but rather plateaus and then decreases during the course of an action potential.

7. What does it mean to say that action potentials are “all or none”?

8. What prevents a nerve signal from traveling “backwards” toward the cell body?

9. Why is the cell unable to initiate another action potential if stimulated during the refractory period?

10. Myelination increases the velocity of action potential propagation along an axon. What is myelination? Myelination causes clustering of voltage-gated Na⁺ channels and Na⁺/K⁺ pumps at nodes of Ranvier along the axon. Predict the consequences to action potential propagation of increasing the spacing between nodes of Ranvier by a factor of 10.

11. Describe the mechanism of action for addictive drugs such as cocaine.

12. Acetylcholine is a common neurotransmitter released at the synapse. Predict the consequences for muscle activation of decreased acetylcholine esterase activity at nerve-muscle synapses.

13. Describe the ion dynamics of the muscle-contraction process.

14. Following the arrival of an action potential in stimulated cells, synaptic vesicles rapidly fuse with the presynaptic membrane. This happens in less than l ms. What mechanisms allow this process to take place at such great speed?

15. Neurons, particularly those in the brain, receive multiple excitatory and inhibitory signals. What is the name of the extension of the neuron at which such signals are received? How does the neuron integrate these signals to determine whether or not to generate an action potential?

16. Explain the mechanism by which action potentials are prevented from being propagated to a postsynaptic cell if transmitted across an inhibitory synapse.

17. What is the role of dynamin in recycling synaptic vesicles? What evidence supports this?

18. Compare and contrast electrical and chemical synapses.

19. Compare the structures and functions of the receptor molecules for salty and sour taste; the taste-receptor molecules for sweetness, bitterness, and umami; and odor-receptor molecules.

20. Describe a synaptic mechanism underlying the formation of memory.