Nervous System I: Basic Structure and Function

Answer: C

15. Myelin is rich in ___________.
16. nucleic acids
17. carbohydrates
18. lipids
19. salts

Answer: C

16. Which of the following is(are) a type of neuroglia?
17. Astrocyte
18. Oligodendrocyte
19. Schwann cell
20. All of the above

Answer: D

17. Which cells produce myelin in the brain and spinal cord?
18. Schwann cells
19. Astrocytes
20. Microglia
21. Oligodendrocytes

Answer: D

18. A reason that the axons in the CNS and PNS differ in their ability to regenerate after injury is that
19. axons of the CNS lack myelin.
20. axons of the CNS lack neurilemmae.
21. peripheral nerves lack Schwann cells.
22. peripheral nerves lack endoneurium.

Answer: B

19. Most of the neurons in the brain and spinal cord are
20. bipolar.
21. unipolar
22. multipolar.
23. nonpolar.

Answer: C

20. In order for a severed peripheral nerve to regenerate and recover its original function, nerve fibers must sprout and enter tubes formed by
21. basement membranes and connective tissues.
22. former axons.
23. myelin.
24. nodes of Ranvier.

Answer: A

21. Which of the following cells is found only in the PNS?
22. Oligodendrocyte
23. Astrocyte
24. Microglial cell
25. Schwann cell

Answer: D

22. Dendrites on unipolar neurons are parts of
23. sensory neurons.
24. motor neurons.
25. interneurons.
26. efferent neurons.

Answer: A

23. Clusters of neuron cell bodies in the PNS are called _____.
24. neuromas
25. axons
26. ganglia
27. nuclei

Answer: C

24. Which of the following neuroglia are not part of the CNS?
25. Ependymal cells
26. Astrocytes
27. Satellite cells
28. Microglia

Answer: C

25. Synaptic knobs are at the ends of
26. axons.
27. dendrites.
28. cell bodies.
29. neuroglia.

Answer: A

26. Presynaptic neurons release neurotransmitters by ______________.
27. endocytosis.
28. exocytosis.
29. diffusion.
30. active transport.

Answer: B

27. When an action potential passes over the surface of a synaptic knob, the contents of the vesicles are released in response to the presence of
28. calcium ions.
29. sodium ions.
30. neurotransmitters.
31. neuropeptides.

Answer: A

28. If a neuron receives a series of stimuli whose effect is excitatory but subthreshold, the neuron is more excitable to incoming stimulation than before and is said to be
29. graded.
30. amplified.
31. facilitated.
32. refractory.

Answer: C

29. Transmitting an impulse from one neuron to another involves a(n)
30. impulse stimulating presynaptic dendrites to release a neurotransmitter into a synaptic cleft.
31. impulse stimulating a presynaptic axon to release a neurotransmitter into a synaptic cleft.
32. neurotransmitter traveling from presynaptic dendrites across a synapse to postsynaptic axons or a cell body.
33. neurotransmitter traveling from postsynaptic axons across a synapse to presynaptic dendrites or a cell body.

Answer: B

30. Action potentials are related to impulses conducted along an axon in that
31. many impulses are required to cause one action potential.
32. active transport of Na+ and K+ are required for impulse conduction but not for an action potential.
33. impulses are stronger responses than are action potentials.
34. propagation of a series of action potentials along a nerve cell fiber constitutes an impulse.

Answer: D

31. A stimulus great enough to change the membrane potential and propagate an action potential is said to have reached _________.
32. recruitment
33. threshold
34. summation
35. tetanus

Answer: B

32. When a nerve fiber is polarized, the concentration(s) of
33. Na+ and K+ are higher on the inside of the membrane.
34. Na+ and K+ are higher on the outside of the membrane.
35. Na+ is higher on the inside of the membrane and K+ is higher on the outside.
36. Na+ is higher on the outside of the membrane and K+ is higher on the inside.

Answer: D

33. Saltatory conduction
34. occurs only if the myelin sheath is continuous.
35. occurs only if nodes of Ranvier are lacking.
36. is faster than conduction on an unmyelinated fiber.
37. is slower than conduction on an unmyelinated fiber.

Answer: C

34. The most rapid conduction of an impulse along an axon occurs on a fiber that is
35. thick and myelinated.
36. thick and unmyelinated.
37. thin and myelinated.
38. thin and unmyelinated.

Answer: A

35. Which of the following ions cross neuron cell membranes most readily?
36. Potassium
37. Sodium
38. Calcium
39. Magnesium

Answer: A

36. If a resting potential becomes more negative, the membrane is
37. depolarized.
38. hyperpolarized.
39. repolarized.
40. summated.

Answer: B

37. What is the correct sequence of events along an axon that follows a membrane reaching threshold potential?
38. The membrane depolarizes.
39. Sodium channels open and sodium ions diffuse inward.
40. The membrane repolarizes.
41. Potassium channels open and potassium ions diffuse outward.
42. 3, 2, 4, 1
43. 2, 1, 4, 3
44. 1, 2, 4, 3
45. 4, 1, 3, 2

Answer: B

38. A nerve cell membrane becomes depolarized as a result of
39. calcium leaving the nerve cell.
40. some ion channels being opened while others are closed.
41. the relative ease with which K+ diffuses into the nerve cell.
42. Na+ being prevented from passing through the membrane.

Answer: B

39. Which of the following molecules is responsible for "runner's high," a good feeling that accompanies long-distance running?
40. Beta endorphin
41. Acetylcholine
42. Epinephrine
43. Dopamine

Answer: A

40. An excitatory postsynaptic potential lasts for about
41. 15 minutes.
42. 15 seconds.
43. 15 milliseconds.
44. 15 microseconds.

Answer: C

41. Each neuron in the CNS may receive input from
42. only one synaptic knob.
43. one synaptic knob at each end.
44. about 10 dendrites.
45. thousands of axons.

Answer: D

42. An action potential is triggered if
43. EPSPs overpower IPSPs.
44. IPSPs overpower EPSPs.
45. chloride channels open.
46. the membrane hyperpolarizes.

Answer: A

43. The neurotransmitter that controls skeletal muscle contraction is
44. beta endorphin.
45. nitric oxide.
46. acetylcholine.
47. GABA.

Answer: C

44. Viagra is a drug used to treat erectile dysfunction by dilating arteries in the penis. The neurotransmitter that Viagra affects is
45. acetylcholine.
46. nitric oxide.
47. serotonin.
48. histamine.

Answer: B

45. Neurotransmitters that are modified amino acids are
46. dopamine, serotonin, epinephrine, and norepinephrine.
47. enkephalins, endorphins, and substance P.
48. aspartic acid, glutamic acid, glycine, and GABA.
49. potassium, sodium, and calcium ions

Answer: A

46. Drugs that increase the actions of norepinephrine and/or serotonin by keeping them in synapses longer are most likely used to treat
47. multiple sclerosis.
48. Tay-Sachs disease.
49. clinical depression.
50. erectile dysfunction.

Answer: C

47. In reuptake
48. an action potential reverses direction.
49. a neuropeptide breaks down into amino acids, which act as neurotransmitters.
50. a neurotransmitter that has already been released into the synaptic cleft is taken back into the synaptic knob of the presynaptic neuron or into nearby neuroglia or neurons.
51. an enzyme breaks down a neurotransmitter and then another enzyme builds it back up.

Answer: C

48. Drugs that inhibit the enzyme monoamine oxidase
49. allow increased activity of norepinephrine.
50. decompose norepinephrine.
51. decrease the activity of serotonin.
52. decompose serotonin.

Answer: A

49. The types of neurons that are organized into neuronal pools are
50. interneurons.
51. intraneurons.
52. Schwann cells.
53. astrocytes.

Answer: A

50. Convergence refers to
51. dendrites from neurons in different parts of the nervous system contacting the same neuron.
52. axons from neurons in different parts of the nervous system contacting the same neuron.
53. dendrites from the same neuron touching each other.
54. a neuroglial cell that contacts many neurons.

Answer: B

51. Diverging axons amplify an impulse by
52. contacting many neurons.
53. returning the impulse to the neuron of origin.
54. splitting into multiple axons.
55. stimulating themselves.

Answer: A

52. Neural stem cells can be harvested from autopsies and stored, alive, in banks, whereas neurons cannot, because
53. people do not will them to science.
54. neural stem cells have lower oxygen and energy requirements than neurons.
55. neural stem cells have higher oxygen and energy requirements than neurons.
56. neural stem cells have more globular shapes than neurons.

Answer: B

53. Migraine results from
54. release of calcitonin gene-related peptide from the trigeminal nerves at the base of the brain, in response to a spreading wave of excitation followed by lack of response from the cortex.
55. not eating enough chocolate, which causes a spreading effect in the cortex.
56. a neurotransmitter deficiency.
57. release of an abnormal form of beta endorphin from the trigeminal nerves at the base of the brain, in response to cortical stimulation.

Answer: A

54. An immune response that affects the myelin coating on axons throughout the spinal cord and brain, triggering inflammation and leaving scars, is
55. muscular dystrophy.
56. multiple sclerosis.
57. Alzheimer disease.
58. amyotrophic lateral sclerosis.

Answer: B

55. Drugs that decrease membrane permeability to sodium
56. are used as local anesthetics.
57. prevent nerve impulses from passing through the affected body part.
58. lessen pain.
59. all of the above.

Answer: D

56. Opiate drugs derived from poppies relieve pain in humans because the human nervous system has
57. neurotransmitters.
58. receptors for endogenous opiates.
59. myelin.
60. sodium and potassium membrane channels.

Answer: B

57. Marjorie takes an anti-anxiety drug so that she can sleep better and remain calm enough to study effectively. She begins by taking 25 milligrams every evening, but within a month this dose is no longer helping, so she takes two pills. After another month this dosage is no longer effective. This is happening because

1. her immune system is rejecting the drug.
2. she has developed tolerance, which means that her liver can no longer metabolize the drug, so it remains active for too long.
3. the number of receptors to which the drug binds on neurons has declined.
4. the number of receptors to which the drug binds on neurons has increased.

Answer: C

58. The neurotransmitter most likely produced when a person uses a drug that creates a sense of well-being is
59. glutamic acid.
60. dopamine.
61. enkephalin.
62. substance Q.

Answer: B

59. A drug that functions as an agonist
60. activates a receptor, helping a neurotransmitter bind or triggering an action potential in some other way.
61. causes great pain if taken in too high a dose.
62. blocks a receptor so that the neurotransmitter cannot bind.
63. relieves pain.

Answer: A

True / False Questions

60. A nerve is a single neuron that transmits impulses.

FALSE

61. Neuroglia are specialized to react to environmental change, and neurons support neuroglia.

FALSE

62. The brain and spinal cord comprise the central nervous system.

TRUE

63. Sensory receptors are part of the CNS.

FALSE

64. The somatic nervous system controls voluntary actions and the autonomic nervous system oversees involuntary actions.

TRUE

65. Axon branches are called collaterals.

TRUE

66. Myelin is composed largely of carbohydrates.

FALSE

67. Nodes of Ranvier lie between neurons.

FALSE

68. Astrocytes structurally support neurons and also provide important signals and nutrients to neurons.

TRUE

69. Interneurons are specialized to carry impulses from receptor cells into the brain or spinal cord.

FALSE

70. A mixed nerve includes different neuroglial cells.

FALSE

71. The space between neurons is called the neuronal space.

FALSE

72. During the absolute refractory period, a stimulus of high intensity may trigger a nerve impulse.

FALSE

73. Because the response of a nerve fiber is all-or-none, a greater intensity of stimulus does not produce a stronger impulse.

TRUE

74. Enkephalins are neuropeptides.

TRUE

75. In convergence, two or more incoming fibers contact a single neuron, whereas in divergence, impulses leaving a neuron pass into several output fibers.

TRUE

76. Several nerve fibers converging onto one neuron amplifies impulses.

FALSE

Fill in the Blank Questions

77. The cells in the nervous system that fill spaces and support neurons both physically and nutritionally are called ______.

neuroglia

78. Muscles and glands that respond to nervous stimulation are called _______.

effectors

79. Sheaths of ______ cells often enclose the larger axons outside of the brain and spinal cord.

Schwann

80. A(n) ______ is the junction between neurons.

synapse

81. The difference in electrical charge between the inside and outside of a polarized neuron cell membrane is called the ______ ______.

resting potential

82. An impulse conducted along an axon consists of a wave of ______ ______ moving away from a point of stimulation.

action potentials

83. A series of similar stimuli that induces change in local membrane potential is called _______.

summation

84. Neuropeptides that affect a neuron's response to other neurotransmitters are called _______.

neuromodulators

85. If a neurotransmitter hyperpolarizes a cell membrane and an action potential is less likely, the change is called ______ ______ ______.

inhibitory postsynaptic potential