Which of the following structures is not part of the central nervous system?

a. The brain

b. A nerve

c. The spinal cord

d. A tract

Match the names of the supporting cells found in column B with the appropriate descriptions in column A.

Column A 

_______ (1) myelinates nerve fibers in the CNS 

_______ (2) lines brain cavities 

_______ (3) myelinates nerve fibers in the PNS 

_______ (4) CNS phagocyte

________(5) helps regulate the ionic composition of CNS extracellular fluid

Column B

a. Astrocyte

b. Ependymal cell

c. Microglial cell

d. Oligodendrocyte

e. Satellite cell

f. Schwann cell

Assume that an EPSP is being generated on the dendritic membrane. Which will occur?

a. Specific Na⁺ channels will open.

b. Specific K⁺ channels will open.

c. A single type of channel will open, permitting simultaneous flow of Na⁺ and K⁺.

d. Na⁺ channels will open first and then close as K⁺ channels open.

Chemical synapses are characterized by all of the following except

a. The release of neurotransmitter by the presynaptic membranes

b. Postsynaptic membranes bearing receptors that bind neurotransmitter

c. Ions flowing through protein channels from the presynaptic to the postsynaptic neuron

d. A fluid-filled gap separating the neurons

Biogenic amine neurotransmitters include all but

a. Norepinephrine

b. Acetylcholine

c. Dopamine

d. Serotonin

Neuropeptides that act as natural opiates include

a. Substance P

b. Somatostatin and cholecystokinin

c. Tachykinins

d. Enkephalins

The anatomical region of a multipolar neuron where the AP is initiated is the

a. Soma

b. Dendrites

c. Axon's initial segment

d. Axon terminals

An IPSP is inhibitory because

a. It hyperpolarizes the postsynaptic membrane.

b. It reduces the amount of neurotransmitter released by the presynaptic terminal.

c. It prevents calcium ion entry into the presynaptic terminal.

d. It changes the threshold of the neuron.

Identify the neuronal circuits described by choosing the correct response from the key.

Key:

a. Converging

b. Diverging

c. Parallel after-discharge

d. Reverberating

_____(1) Impulses continue around and around the circuit until one neuron stops firing.

_____(2) One or a few inputs ultimately influence large numbers of neurons.

_____(3) Many neurons influence a few neurons.

_____(4) May be involved in exacting types of mental activity.

a. What is myelin?

b. How does the myelination process differ in the CNS and PNS?

Since all APs generated by a given nerve fiber have the same magnitude, how does the CNS 'know' whether a stimulus is strong or weak?

Briefly describe the three stages of neuron development.

The velocity of nerve impulse conduction is greatest in

a. Heavily myelinated, large-diameter fibers

b. Myelinated, small-diameter fibers

c. Nonmyelinated, small-diameter fibers

d. Nonmyelinated, large-diameter fibers

a. Describe the composition and function of the cell body.

b. How are axons and dendrites alike? In what ways (structurally and functionally) do they differ?

a. Contrast unipolar, bipolar, and multipolar neurons structurally.

b. Indicate where each is most likely to be found.

What is the polarized membrane state? How is it maintained? (Note the relative roles of both passive and active mechanisms.)

a. Explain the difference between an EPSP and an IPSP.

b. What specifically determines whether an EPSP or IPSP will be generated at the postsynaptic membrane?

Since at any moment a neuron is likely to have thousands of neurons releasing neurotransmitters at its surface, how is neuronal activity (to fire or not to fire) determined?

The effects of neurotransmitter binding are very brief. Explain.

When admitted to the emergency room, Sean was holding his right hand, which had a deep puncture hole in its palm. He explained that he had fallen on a nail while exploring a barn. Sean was given an antitetanus shot to prevent neural complications. Tetanus bacteria fester in deep, dark wounds, but how do their toxins travel in neural tissue?

Local anesthetics block voltage-gated Na⁺ channels. General anesthetics are thought to activate chemically gated Cl⁻ channels, thereby rendering the nervous system quiescent while surgery is performed. What specific process do anesthetics impair, and how does this interfere with nerve impulse transmission?

Rochelle developed multiple sclerosis when she was 27. After eight years she had lost a good portion of her ability to control her skeletal muscles. How did this happen?

In the Netherlands a young man named Jan was admitted to the emergency room. He and his friends had been to a rave. His friends say he started twitching and having muscle spasms which progressed until he was 'stiff as a board.' On examination, staff found a marked increase in muscle tone and hyperreflexia involving facial and limb muscles. In his pocket, he had unmarked dark yellow tablets with dark flecks. Analysis of the tablets showed them to contain a mixture of ecstasy and strychnine. Ecstasy would not cause this clinical picture, but strychnine, which blocks glycine receptors, could. Explain how.