Chapter 1

What are the widely branching structures of a neuron called? And what is the long, thin structure that carries information to another cell called?

Which animal species would have the longest axons?

Identify the four major structures that compose a neuron.

Which kind of glia cell wraps around the synaptic terminais of axons?

Identify one major advantage and one disadvantage of having a blood-brain barrier.

When the membrane is at rest, are the sodium ions more concentrated inside the cell or outside? Where are the potassium ions more concentrated?

When the membrane is at rest, what tends to drive the potassium ions out of the cell? What tends to draw them into the cell?

What is the difference between a hyperpolarization and a depolarization?

What is the relationship between the threshold and an action potential?

During the rise of the action potential, do sodium ions move into the cell or out of it? Why?

As the membrane reaches the peak of the action potential, what brings the membrane down to the original resting potential?

State the all-or-none law.

Does the all-or-none law apply to dendrites? Why or why not?

Suppose researchers find that axon A can produce up to 1,000 action potentials per second (at least briefly, with maximum stimulation), but axon \(\mathrm{B}\) can never produce more than 100 per second (regardless of the strength of the stimulus). What could we conclude about the refractory periods of the two axons?

In a myelinated axon, how would the action potential be affected if the nodes were much closer together? How might it be affected if the nodes were much farther apart?