Vander's Ch 6
31. Neuronal axons typically have abundant A. voltage-gated channels for Na+ that open in response to depolarization. B. voltage-gated channels for K+ that open in response to hyperpolarization. C. receptor-mediated channels for Na+. D. receptor-mediated channels for K+. E. voltage-gated channels for Ca2+.
a
95. The cerebrum consists only of gray matter. True False
f
97. The thalamus is the single most important control area for regulating the homeostasis of the internal environment. True False
f
13. Which would result from an increase in the extracellular concentration of K+ above normal? A. depolarization of resting nerve cells B. hyperpolarization of resting nerve cells C. The potassium equilibrium potential of nerve cells would become more negative. D. The sodium equilibrium potential would become less positive.
a
41. At an excitatory chemical synapse between two neurons, A. there is increased permeability of the postsynaptic cell to both Na+ and K+. B. a small hyperpolarization of the postsynaptic membrane occurs when the synapse is activated. C. an action potential in the presynaptic neuron always causes an action potential in the postsynaptic neuron. D. excitation occurs because K+ enters the postsynaptic cell. E. action potentials spread through gap junctions between cells.
a
45. Which best describes temporal summation? A. A synapse is stimulated a second time before the effect of a first stimulus at the synapse has terminated. B. It only refers to addition of EPSPs. C. Two synapses on different regions of a cell are stimulated at the same time. D. It always brings a postsynaptic cell to threshold. E. The size of an EPSP depends on the size of the stimulus.
a
53. Which of the following statements regarding neurotransmitters is TRUE? A. Acetylcholine is broken down by enzymes present on postsynaptic cell membranes. B. Acetylcholine that is released at synapses binds to adrenergic receptors in the postsynaptic cell membrane. C. Catecholamines are the most abundant neurotransmitters in the central nervous system. D. Opiate drugs, such as morphine, are antagonists of a class of neurotransmitters called endorphins. E. Gamma-aminobutyric acid (GABA) is a major excitatory transmitter in the central nervous system.
a
56. Which of the following enzymes is important for the metabolism of catecholamines? A. Tyrosine hydroxylase B. Acetylcholinesterase C. Superoxide dismutase D. Hydrocortinase E. Adenyl cyclase
a
58. Serotonin: A. acts as a neuromodulator. B. is a catecholamine neurotransmitter. C. is a neuropeptide. D. has an inhibitory effect on pathways that are involved in the control of muscles. E. has an excitatory effect on pathways that mediate sensations.
a
6. The difference in electrical charge between two points: A. is called the potential difference between those points. B. is called the diffusion potential between those points. C. is called the the current, and is expressed in the units of millimoles. D. is the same for all ions.
a
61. Which is one of the most abundant excitatory neurotransmittors in the CNS? A. Glutamate B. Dopamine C. Norepinephrine D. Gamma-aminobutyric acid (GABA) E. Endorphin
a
70. The cerebellum: A. is important for coordinating body movement. B. is the gray matter covering the entire surface of the brain. C. is the same thing as the brain stem. D. is in the anterior portion of the brain, just above the eyes. E. is one of the basal nuclei that is found deep inside the cerebrum.
a
15. Which of these would occur if the concentration of ATP were depleted in a typical nerve cell? A. Resting membrane potential would become more negative. B. Resting membrane potential would become less negative. C. The concentration gradient for Na+ would remain the same. D. The resting membrane potential would eventually become positive inside with respect to outside. E. There would be no change in the resting membrane potential.
b
22. Which must happen in order for an action potential to begin? A. The membrane potential must be at the Na+ equilibrium potential. B. Na+ influx must exceed K+ efflux. C. The membrane must be out of the relative refractory period. D. Na+ channels must all be inactivated. E. Multiple inhibitory postsynaptic potentials (IPSPs) must summate.
b
28. Which of the following statements about the phases of a neuronal action potential is true? A. During the after-hyperpolarization phase, the permeability of the membrane to sodium ions is greater than its permeability to potassium ions. B. During the after-hyperpolarization phase, the permeability of the membrane to potassium ions is greater than its permeability at rest. C. During the repolarizing phase, the permeability of the membrane to sodium ions is greater than its permeability to potassium ions. D. Potassium channels inactivate during the depolarization phase. E. Repolarizing to negative membrane potentials causes the sodium channels to inactivate.
b
34. How is the strength of a stimulus encoded by neurons? A. by the size of action potentials B. by the frequency of action potentials C. by the duration of action potentials D. by whether the action potential peak is positive or negative
b
48. Which is TRUE about the initial segment of an axon? A. Its threshold potential is more positive than that of the cell body and dendrites. B. Its threshold potential is more negative than that of the cell body and dendrites. C. Synapses far from the initial segment are more effective in influencing whether an action potential will be generated in the axon than are synapses close to the initial segment. D. It is the region where neurotransmitter vesicles are docked and ready to be released by exocytosis. E. It can only conduct graded potentials because it lacks voltage-gated Na+ channels.
b
49. A presynaptic synapse: A. is a synapse between an axon terminal and a dendrite that can be either excitatory or inhibitory. B. is a synapse between an axon terminal and another axon's terminal that can be either excitatory or inhibitory. C. is any synapse onto a cell body, and they can be either stimulatory or inhibitory. D. is a synapse between an axon terminal and a dendrite of the same cell, which is always inhibitory. E. is a synapse between an axon terminal and another axon terminal that is always inhibitory.
b
65. Which of the following kinds of neurons is not generally cholinergic? A. somatic motor neurons B. postganglionic sympathetic neurons C. postganglionic parasympathetic neurons D. preganglionic sympathetic neurons E. preganglionic parasympathetic neurons
b
21. A threshold stimulus applied to an excitable membrane is one that is just sufficient to: A. trigger an excitatory postsynaptic potential. B. cause a change in membrane potential. C. trigger an action potential. D. be conducted to the axon hillock. E. depolarize a dendrite.
c
3. Which of the following is not true about axon transport? A. It refers to the passage of materials from the cell body of a neuron to the axon terminals. B. It refers to the passage of materials from axon terminals to the cell body of a neuron. C. It refers to the transport of materials from the inside to the outside across the axonal membrane. D. It is especially important for maintaining the integrity of neurons with long axons.
c
40. The main role of calcium ions at chemical synapses is to A. depolarize the axon terminal of the presynaptic cell. B. bind to neurotransmitter receptors on the postsynaptic cell. C. cause fusion of synaptic vesicles with the plasma membrane of the axon terminal. D. interfere with IPSPs in the postsynaptic cell. E. diffuse across the synaptic space and enter the postsynaptic cell.
c
51. Which of the following is not known to be an important neurotransmitter in the CNS? A. Dopamine B. Acetylcholine C. Morphine D. Glutamate E. Substance P
c
57. Nicotine is: A. a cholinergic antagonist. B. a beta-adrenergic agonist. C. a cholinergic agonist. D. an alpha-adrenergic antagonist. E. a neurotransmitter.
c
59. Alzheimer's disease is thought to involve primarily: A. loss of neurons that secrete or respond to catecholamines. B. loss of adrenergic neurons. C. loss of cholinergic neurons. D. loss of neurons that secrete or respond to dopamine. E. tumors that produce excess serotonin.
c
7. According to the equation expressed as Ohm's law, which of these would cause the greatest increase in current? A. doubling both voltage and resistance B. reducing both voltage and resistance by half C. doubling voltage and reducing resistance by half D. reducing voltage by half and doubling resistance E. quadrupling both voltage and resistance
c
71. The ________________ is best described as "an interconnected group of brain structures including parts of the frontal lobe-cortex, temporal lobe, thalamus, and hypothalamus, that is associated with learning, emotional experience, and behavior?" A. diencephalon B. cerebrum C. limbic system D. reticular formation E. cerebellum
c
11. The membrane potential of most neurons at rest is: A. equal to the equilibrium potential for potassium. B. equal to the equilibrium potential for sodium. C. slightly more negative than the equilibrium potential of potassium ion. D. more positive than the equilibrium potential for potassium. E. more positive than the equilibrium potential for sodium.
d
27. Why are action potentials sometimes described as being "all-or-none" in character? A. The rate of propagation of an action potential down an axon is independent of stimulus strength. B. They are associated with an absolute refractory period. C. A supra-threshold stimulus is required to stimulate an action potential during the relative refractory period. D. An action potential occurs whenever a suprathreshold stimulus occurs, and its amplitude does not vary with the size of a stimulus. E. Action potentials are always the same size, even when ion gradients vary in size.
d
38. Which is FALSE about interneurons? A. They receive synaptic input from other other neurons in the CNS. B. They sum excitatory and inhibitory synaptic inputs. C. They deliver synaptic input on other neurons. D. They make synapses on effector organs in the PNS. E. They can transmit information between afferent neurons and efferent neurons.
d
63. The portion of the peripheral nervous system that is composed of nerve fibers that innervate skeletal muscle is called the: A. afferent nervous system. B. sympathetic nervous system. C. parasympathetic nervous system. D. somatic motor nervous system. E. autonomic nervous system.
d
74. Postganglionic neuron cell bodies of the autonomic nervous system have which category of neurotransmitter receptor? A. Adrenergic receptor B. Serotonin receptors C. Muscarinic acetylcholine receptors D. Nicotinic acetylcholine receptors E. Dopamine receptors
d
19. Which is NOT an example of a graded potential? A. a receptor potential in a sensory receptor cell B. a depolarizing excitatory postsynaptic potential (EPSP) C. a hyperpolarizing inhibitory postsynaptic potential (IPSP) D. a depolarizing pacemaker potential E. a depolarizing action potential
e
26. Which is most directly responsible for the falling (repolarizing) phase of the action potential? A. Voltage-gated Na+ channels are opened. B. The Na+, K+ pump restores the ions to their original locations inside and outside of the cell. C. The permeability to Na+ increases greatly. D. ATPase destroys the energy supply that was maintaining the action potential at its peak. E. The permeability to K+ increases greatly while that to Na+ decreases.
e
36. An action potential does not re-stimulate the adjacent membrane that was previously depolarized because A. stimulation is inhibited by the myelin sheath. B. it is impossible for an action potential to be propagated along an axon toward the nerve cell body. C. the resting membrane potential of the axon is too positive. D. the resting membrane potential of the axon is too negative. E. that area of the membrane is in the absolutely refractory period.
e
4. Which is FALSE about neurons? A. A given neuron can be either a presynaptic neuron or a postsynaptic neuron. B. An individual neuron can receive information from multiple other neurons. C. An individual neuron can transmit information to multiple other neurons. D. A neuron can simultaneously release more than one type of neurotransmitter. E. A neuron receives information on its axons and delivers it to other neurons through its dendrites.
e
43. Which of the following statements about EPSPs is false? A. They are produced by the opening of chemically-gated sodium channels. B. They transmit signals over relatively short distances. C. They depolarize postsynaptic cell membranes. D. They are able to summate. E. They are always the same amplitude.
e
54. Acetylcholine is the main neurotransmitter released by: A. preganglionic sympathetic neurons and cells of the adrenal medulla. B. cells of the adrenal medulla and postganglionic parasympathetic neurons. C. motor neurons and postganglionic sympathetic neurons. D. preganglionic sympathetic neurons and postganglionic sympathetic neurons. E. preganglionic sympathetic neurons and motor neurons.
e
55. Which of the following statements about norepinephrine is FALSE? A. Norepinephrine is a neurotransmitter. B. Norepinephrine binds to adrenergic receptors. C. Norepinephrine is a catecholamine. D. Dopamine is a precursor to norepinephrine. E. Epinephrine is a precursor to norepinephrine.
e
62. The central nervous system includes the: A. afferent nerves and spinal cord. B. efferent nerves and spinal cord. C. autonomic nervous system and the brain. D. brain stem and the autonomic nervous system. E. brain and spinal cord.
e
100. Most of the parasympathetic ganglia lie in chains along the spinal cord called sympathetic trunks. True False
f
103. "Dual innervation of effectors" refers to the innervation of the same effector organs by somatic and autonomic nerves. True False
f
84. The action potential elicited by a supra-threshold stimulus is larger than one elicited by a threshold stimulus. True False
f
102. The sympathetic division of the autonomic nervous system is arranged so that it acts largely as a unit, whereas the components of the parasympathetic division generally act as discreet, independent components. True False
t
90. Opioid drugs, such as morphine, are agonists of a class of neurotransmitters called endorphins. True False
t
12. The diffusion potential due to the concentration gradient for Na+ across a nerve cell membrane: A. favors its movement into the cell at the resting membrane potential. B. favors its movement out of the cell at the resting membrane potential. C. is equal and opposite to the electrical potential acting on Na+ at the resting membrane potential. D. Is in the same direction as the diffusion potential due to the concentration gradient for K+. E. favors movement of Na+ in the opposite direction as the electrical potential acting on Na+ at the resting membrane potential.
a
76. The lipid portion of a cell's plasma membrane constitutes a barrier to current. True False
t
78. The maintenance of a resting potential in a neuron depends indirectly upon the functioning of the Na+, K+-ATPase pumps in the membrane. True False
t
79. A graded potential in a membrane results in an electric current along an adjacent area of membrane and this current diminishes with distance from the site of the initial potential change. True False
t
80. During a hyperpolarizing graded potential, positively charged ions flow away from the site of the initial hyperpolarization on the outside of membrane and toward this site on the inside. True False
t
82. The Na+ and K+ channels that open during an action potential are voltage regulated, both opening in response to depolarization of the membrane. True False
t
86. The absolute refractory period of an excitable membrane roughly corresponds to the period when sodium channels are opening and inactivated. True False
t
93. Spinal nerves are composed of the axons of both afferent and efferent neurons. True False
t
96. The basal ganglia are important subcortical nuclei in the cerebrum. True False
t
25. Which is true about neuronal membrane electrical and concentration gradients at the peak of the action potential? A. The electrical gradient is in a direction that would tend to move K+ out of the cell. B. The concentration gradient for K+ is in a direction that would tend to move it into the cell. C. The concentration gradient for K+ greatly increases compared to at rest. D. The concentration gradient for Na+ is in a direction that would tend to move it out of the cell. E. The electrical gradient for Na+ is in a direction that would tend to move it into the cell.
a
32. Which of the following statements regarding action potentials generated in a neuronal membrane is not true? A. Action potentials travel decrementally down the membrane. B. An action potential generates a new action potential in an adjacent area of membrane. C. An action potential generates a local current that depolarizes adjacent membrane to threshold potential. D. Action potentials are usually initiated at the initial segment of a neuron. E. An action potential generated by a threshold stimulus is the same size as one generated by a supra-threshold stimulus.
a
33. Which of the following statements concerning the properties of action potentials is true? A. The rate of propagation of an action potential down an axon is independent of stimulus strength. B. Action potentials can undergo summation. C. A supra-threshold stimulus can stimulate an action potential during the absolute refractory period. D. Action potentials generally propagate from the axon terminal toward the initial segment. E. Increasing the size of a stimulus will increase the amplitude of an action potential.
a
44. An EPSP: A. is a direct result of the opening of ligand-gated channels permeable to both Na+ and K+ ions. B. is a direct result of the opening of voltage-gated channels permeable to both Na+ and K+ ions. C. stabilizes the membrane to remain at its resting potential. D. opens voltage-gated Ca2+ channels in the presynaptic membrane. E. occurs when voltage-gated Cl- channels open in a postsynaptic cell membrane.
a
20. An action potential in a neuronal membrane differs from a graded potential in that: A. an action potential requires the opening of Ca2+ channels, whereas a graded potential does not. B. an action potential is propagated without decrement, whereas a graded potential decrements with distance. C. an action potential has a threshold, whereas a graded potential is an all-or-none phenomenon. D. movement of Na+ and K+ across cell membranes mediate action potentials, while graded potentials do not involve movement of Na+ and K+. E. action potentials vary in size with the size of a stimulus, while graded potentials do not.
b
23. Which describes the response of the voltage-gated channels when an axon is stimulated to threshold? A. K+ channels open before the Na+ channels. B. Na+ channels are activated and then inactivated. C. K+ channels open at the same time as the Na+ channels. D. K+ channels are opened when Na+ binds to the channel. E. K+ influx causes Na+ channels to inactivate.
b
24. During the rising (depolarizing) phase of a neuronal action potential, A. PK+ becomes much greater than PNa+. B. PNa+ becomes much greater than PK+. C. PK+ is the same as PNa+. D. Na+ efflux (flow out of the cell) occurs. E. K+ flows rapidly into the cell.
b
37. The regions of axon membrane that lie between regions of myelin are the A. islets of Langerhans. B. nodes of Ranvier. C. synaptic membranes. D. glial cells. E. dens of iniquities.
b
42. An inhibitory postsynaptic potential: A. is produced by simultaneous increases in permeability to both Na+ and K+. B. occurs when a ligand-gated ion channel increases its permeability to K+. C. is a small depolarization in a postsynaptic cell. D. can be summed with other IPSPs to trigger an action potential in the postsynaptic cell. E. is produced by an increase in permeability to only Na+.
b
5. Which of the following is not true of glial cells? A. They form the myelin for axons. B. Neurons outnumber glial cells 10 to 1 in the nervous system. C. They deliver fuel molecules to neurons and remove the waste products of metabolism. D. They are important for the growth and development of the nervous system. E. They regulate the composition of the extracellular fluid in the CNS.
b
68. Synthesis of neuropeptides differs from that of other neurotransmitters because it: A. takes place in the axon terminals of neurons. B. takes place in the cell bodies of neurons. C. takes place on ribosomes in the postsynaptic cell's membrane. D. uses amino acids as precursor molecules. E. only takes place at synapses outside the central nervous system.
b
10. Which is TRUE about typical, resting neurons? A. The plasma membrane is most permeable to sodium ions. B. The concentration of sodium ion is greater inside the cell than outside. C. The permeability of the plasma membrane to potassium ions is much greater than its permeability to sodium ions. D. The plasma membrane is completely impermeable to sodium ions. E. The plasma membrane is completely impermeable to potassium ions.
c
35. Which of the following statements concerning the rate of action potential propagation is true? A. It is faster in small-diameter axons than in large-diameter axons. B. It is faster for a strong stimulus than for a weak one. C. It is faster in myelinated axons than in nonmyelinated axons. D. It is faster in the dendrites than in the axon. E. It occurs at the same rate in all axons, regardless of their diameter.
c
39. Exocytosis of neurotransmitter into the synaptic cleft is triggered by an influx of ______ in response to the arrival of an action potential in the axon terminal. A. K+ B. Na+ C. Ca2+ D. ATP E. Cl-
c
46. A postsynaptic neuron has three presynaptic inputs - from neurons X, Y, and Z. Stimulation of neuron X causes the postsynaptic neuron to depolarize by 0.5 mV. When X and Y are stimulated simultaneously, the postsynaptic neuron depolarizes by 1 mV. When X and Z are stimulated simultaneously, however, there is no change in the membrane potential of the postsynaptic neuron. What is most likely true about presynaptic neurons Y and Z? A. They are both excitatory. B. They are both inhibitory. C. Y is excitatory and Z is inhibitory. D. Z is excitatory and Y is inhibitory.
c
67. Drug X interferes with the action of norepinephrine at synapses. Which of the following mechanisms would not explain the effects of X? A. X inhibits synthesis of norepinephrine at the axon terminal. B. X inhibits norepinephrine release from the terminal. C. X blocks reuptake of norepinephrine by the terminal. D. X is an adrenergic receptor antagonist. E. X stimulates the catabolism of norepinephrine.
c
18. Which of the following statements concerning the permeability of a typical neuron membrane at rest is true? A. The permeability to Na+ is much greater than the permeability to K+. B. All of the K+ channels in the membrane are open. C. The voltage-gated Na+ channels are in the inactivated state. D. Most of the voltage-gated Na+ channels are in the closed state. E. There is equal permeability to Na+ and K+.
d
2. Which is not true of myelin? A. It is a fatty membranous sheath. B. It is formed by glial cells. C. It influences the velocity of conduction of an electrical signal down an axon. D. It covers all parts of the neuron, including the axon, cell body, and dendrites.
d
30. The relative refractory period of an axon coincides with the period of A. activation and inactivation of voltage-dependent Na+ channels. B. Na+ permeability that is greater than that during the depolarization phase. C. increased K+ flux into the cell. D. increased K+ permeability of the cell. E. Increased Na+ flux through K+ channels.
d
60. Which is one of the major inhibitory neurotransmittors in the CNS? A. Glutamate B. Dopamine C. Norepinephrine D. Gamma-aminobutyric acid (GABA) E. Beta-endorphin
d
69. Which best describes the reticular formation of the brain? A. It is mainly involved in motor coordination and balance. B. It is the master endocrine gland of the brain. C. It is primarily responsible for visual perception. D. It integrates information from all regions of the CNS, and incorporates the mechanisms that regulate sleep and wakefulness. E. It is the primary synaptic relay station for sensory information entering the CNS.
d
64. The region of the brain that is the most important control area for homeostatic regulation of the internal environment is: A. the thalamus. B. the hippocampus. C. the cerebrum. D. the cerebellum. E. the hypothalamus.
e
75. A myelinated axon is shielded from direct contact with the extracellular fluid all along its length. True False
f
77. Ions other than Na+, K+, and Cl- play no role in generating the resting membrane potential of a cell. True False
f
81. Because so many Na ions move into a cell during an action potential and so many K ions move out, no further action potentials can be generated in a given membrane until the Na, K-ATPase pumps can restore the concentration gradient. True False
f
83. SNARE receptor protein complexes in presynaptic neurons function as inhibitors of calcium transport to dampen or reduce the amount of neurotransmitter vesicles which participate in exocytosis. True False
f
92. Dorsal root ganglia contain the cell bodies of efferent neurons. True False
f
94. Although nerve cells in each cerebral hemisphere make connections with other cells in the same hemisphere, there is no crossover of information between the two hemispheres. True False
f
17. The equilibrium potential of K+ ions in nerve cells is about -90 mV. The membrane potential of typical nerve cells at rest is -70 mV. Therefore A. Increasing the permeability of a resting neuronal membrane to K+ will make the membrane potential more negative inside with respect to outside. B. In resting neurons, there is a net diffusion of K+ into the cell. C. changing the resting membrane potential of a neuron to -80 mV would increase K+ diffusion rate out of the cell. D. potassium is the only permanent ion at rest. E. there must be another permanent ion with an equilibrium potential more negative than -90 mV.
a
14. Which is TRUE about the Na+, K+ ATPase pump in neurons? A. It generates a small electrical potential such that the inside is made negative with respect to the outside. B. It maintains a concentration gradient for K+ such that diffusion forces favor movement of K+ into the cell. C. It maintains an electrical gradient at the equilibrium potential of K+. D. It transports equal numbers of sodium and potassium ions with each pump cycle. E. It pumps 3 Na+ ions into the cell for every 2 K+ ions it pumps out.
a
52. Which of the following statements about acetylcholine is correct? A. Acetylcholine binds to nicotinic and muscarinic receptors. B. Acetylcholine binds to adrenergic receptors. C. Acetylcholine synthesis is catalyzed by acetylcholinesterase D. Acetylcholine is the neurotransmitter released by most sympathetic postganglionic neurons. E. Acetylcholine is generally transported back into presynaptic nerve terminals without being enzymatically degraded.
a
66. Which of the following does NOT result from the binding of nicotine with nicotinic acetylcholine receptors? A. a mild form of skeletal muscle paralysis that creates a more relaxed state B. signal transmission at neuromuscular junctions C. generation of excitatory signals within autonomic ganglia D. the release of norepinephrine, dopamine, and epinephrine E. facilitation of the release of multiple neurotransmitters within the brain, including the "reward pathway" involving dopamine
a
72. Which is a FALSE statement about the cerebrospinal fluid? A. It has the same composition as blood plasma. B. It acts as a cushion for the brain and spinal cord. C. It is secreted by cells lining the ventricles of the brain. D. It circulates within and between brain ventricles and surrounds the spinal cord. E. It is in diffusion equilibrium with the extracellular fluid of the central nervous system.
a
73. Which of the following is NOT characteristic of the sympathetic division of the ANS? A. Preganglionic neurons tend to be long, with the ganglion located in or near the effector target tissue(s). B. Preganglionic neurons are short and synapse in ganglia located near the spinal cord. C. Preganglionic neurons release acetylcholine at synapses with postganglionic neurons. D. Postganglionic neurons release norepinephrine at their neuroeffector junctions. E. Postganglionic neuron cell bodies are located in the collateral chain ganglia (sympathetic trunk).
a
9. Which is TRUE about the resting membrane potential? A. It requires very few ions to be distributed unevenly. B. It has the same value in all cells. C. It is oriented so that the cell's interior is positive with respect to the extracellular fluid. D. Only nerve and muscle cells have a potential difference across the membrane at rest. E. It is not altered by changing concentration gradients of permeating ions.
a
50. Neuron X makes inhibitory axon-axon synaptic contact with neuron Y at the synapse of Y and neuron Z. Which will occur when action potentials are stimulated in neuron X? A. Neuron Y will be inhibited from reaching the threshold to fire an action potential. B. The release of neurotransmitter by neuron Y will be inhibited. C. The synapse between neurons Y and Z will be changed from an excitatory synapse to an inhibitory one. D. Neurons Y and Z will both be more likely to reach threshold and fire an action potential. E. Neurons Y and Z will both be less likely to reach threshold and fire an action potential.
b
47. A postsynaptic neuron has three presynaptic inputs - from neurons X, Y, and Z. When X and Y are stimulated simultaneously and repeatedly, the postsynaptic neuron reaches threshold and undergoes an action potential. When X and Z are stimulated simultaneously, however, there is no change in the membrane potential of the postsynaptic neuron. The simultaneous stimulation of X and Y is an example of A. temporal summation. B. presynaptic inhibition. C. spatial summation. D. neuronal divergence. E. presynaptic facilitation.
c
8. Compartments A and B are separated by a membrane that is permeable to K+ but not to Na+ or Cl-. At time zero, a solution of KCl is poured into compartment A and an equally concentrated solution of NaCl is poured into compartment B. Which would be true once equilibrium is reached? A. The concentration of Na+ in A will be higher than it was at time zero. B. Diffusion of K+ from A to B will be greater than the diffusion of K+ from B to A. C. There will be a potential difference across the membrane, with side B negative relative to side A. D. The electrical and diffusion potentials for K+ will be equal in magnitude and opposite in direction. E. The concentration of Cl- will be higher in B than it was at time zero.
d
1. Which of the following is/are functions of the human nervous system? A. receiving, storing, and processing information on the internal and external environments B. bringing about changes in physiology and/or behavior to ensure optimal functions of homeostatic mechanisms C. secretion of hormones D. coordination of movement E. All of the choices are correct.
e
16. Which is FALSE about the equilibrium potential of a given ion across a membrane? A. It is a function of the concentration of that ion on both sides of the membrane. B. It is the potential at which there is no net movement of that ion across the membrane. C. It is the potential difference across the membrane at which an electric force favoring movement of the ion in one direction is equal in magnitude and opposite in direction to the diffusion force provided by the concentration difference of the ion across the membrane. D. A permeable ion will move in the direction that will tend to bring the membrane potential toward that ion's equilibrium potential. E. An anion that is in higher concentration inside the cell than outside the cell will have a negative eqilibrium potential.
e
29. Which of the following statements about the refractory period of a membrane is true? A. The absolute refractory period refers to the period of time during which another action potential cannot be initiated in that part of the membrane that is undergoing an action potential, no matter how great the strength of the stimulus. B. The relative refractory period refers to the period of time during which another action potential can be initiated in that part of the membrane that has just undergone an action potential if a stronger than normal stimulus is applied. C. The refractory period prevents the action potential from spreading back over the part of the membrane that just underwent an action potential. D. The refractory period places an upper limit on the frequency with which a nerve cell can conduct action potentials. E. All of the above choices are correct.
e
101. Responses made possible by motor signals transmitted by the parasympathetic nervous system tend to be displayed throughout the body simultaneously because there is much divergence of nerve pathways and close anatomical association between presynaptic neurons and their ganglia as well as accessory activity with the adrenal glands. True False
f
85. The relative refractory period of an excitable membrane refers to the period of time during which no stimulus, however strong, will elicit a second action potential in the membrane. True False
f
87. Because all parts of a neuronal cell body have the same threshold, no one synapse on the cell is more important than any other. True False
f
89. Catecholamines are the most abundant neurotransmitters in the CNS. True False
f
91. The most common neurotransmitters for neuroeffector communication are dopamine and acetylcholine. True False
f
88. The frequency of action potentials in a postsynaptic cell is directly related to the degree of depolarization of the postsynaptic cell. True False
t
98. The efferent division of the peripheral nervous system consists of the somatic nervous system and the autonomic nervous system. True False
t
99. Preganglionic fibers of the parasympathetic division of the autonomic nervous system leave the CNS at the level of the brainstem and sacral portions of the spinal cord. True False
t
