Exam 4: Principles of Neural and Hormonal Communication

Complete each of the following statments. A single nerve cell or ____________________ typically consists of the following three basic parts: ____________________, ____________________, and ____________________.

Presynaptic facilitation results from

Schwann cells promote axonal growth, while oligodendrocytes inhibit it.

Saltatory conduction

Threshold potential is the peak potential achieved during an action potential.

Complete each of the following statments. ____________________ move through the axon before being released from the synaptic knob and then bind to nonsynaptic receptors; whereas, ____________________ are made in the cytosol of the synaptic knob and after their release bind to subsynaptic receptors.

Which statement is incorrect?

A balance of IPSPs and EPSPs will negate each other so that the grand postsynaptic potential is essentially unaltered.

Which statement is correct?

The nodes of Ranvier are

During the relative refractory period, a neuron can experience hyperpolarization but not depolarization.

Complete each of the following statments. ____________________ are local chemical messengers that exert an effect only on neighboring cells in the immediate environment.

The trigger zone of a neuron

Complete each of the following statments. The chemical called ____________________ along axons reduces resistance and, hence, increases impulse velocity.

For the following questions, assume a hypothetical postsynaptic neuron has three presynaptic inputs: neurons X, Y, and Z. Also, assume neuron Z is excitatory. If neurons Y and Z receive simultaneous stimulation, what change would you expect in the postsynaptic neuron?

Lipophilic hormones bind to hormone response elements on DNA, which then initiates steps in the formation of new protein molecules.

Which of the following is not a graded potential?

Complete each of the following statments. Myelinated fibers conduct impulses about ____________________ times faster than unmyelinated fibers of the same diameter.

Myelinated axons conduct impulses much faster because