Human Physiology From Cells To Systems 8th Edition Test Bank Lauralee Sherwood

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Human Physiology From Cells To Systems 8th Edition Test Bank Lauralee Sherwood

Description

Chapter 4Principles of Neural and Hormonal Communication

MULTIPLE CHOICE

1. A change in a membrane potential from +30 mV to -70 mV is an example of
a. depolarization
b. hyperpolarization
c. polarization
d. repolarization
e. zero potential

ANS: D PTS: 1 DIF: Comprehension

2. The negative charge established along the cytosolic border a nerve cell membrane is due to
a. movement of sodium ions into the cell
b. movement of proteins out of the cell
c. higher permeability of K+ relative to Na+
d. movement of proteins through membrane channels
e. both b and d

ANS: C PTS: 1 DIF: Comprehension

3. Which of the following is/are found in all cells of excitable and nonexcitable tissues?
a. a threshold potential
b. a resting membrane potential
c. gated ion channels
d. all of the above characteristics
e. mechanically-gated channels

ANS: D PTS: 1 DIF: Knowledge

4. Which term best describes an excitable cell when a resting membrane potential is present?
a. polarized
b. depolarized
c. hyperpolarized
d. repolarized
e. nonpolarized

ANS: A PTS: 1 DIF: Knowledge

5. A threshold potential is
a. the potential achieved when two opposing forces acting upon an ion (concentration and electrical gradients) achieve a state of equilibrium
b. the peak potential achieved during an action potential
c. the point at which there is an explosive increase in Na+ or Ca2+ permeability
d. the potential at which K+ permeability increases
e. always a positive potential

ANS: C PTS: 1 DIF: Knowledge

6. A change in a membrane potential from -70 mV to -60mV is an example of
a. depolarization
b. hyperpolarization
c. polarization
d. repolarization
e. zero potential

ANS: A PTS: 1 DIF: Comprehension

7. Graded potentials
a. are local changes in membrane potential that occur in varying degrees of magnitude
b. are weak action potentials
c. serve as long-distance signals
d. are only depolarizations
e. always lead to action potentials

ANS: A PTS: 1 DIF: Knowledge

8. During the rising phase of the action potential,
a. PK+ is much greater than PNa+
b. PNa+ is much greater than PK+
c. PK+ is the same as P Na+
d. Na+ efflux occurs
e. b and d are true

ANS: B PTS: 1 DIF: Knowledge

9. Which of the following is not a graded potential?
a. end-plate potential
b. action potential
c. slow-wave potential
d. receptor potential
e. postsynaptic potential

ANS: B PTS: 1 DIF: Knowledge

10. Which of the following is responsible for the falling phase of an action potential?
a. opening of Na+ gates
b. Na+-K+ pump restoring the ions to their original locations
c. greatly increased permeability to Na+
d. Na+ efflux
e. none of these

ANS: E PTS: 1 DIF: Comprehension

11. In most excitable cells, the rising phase of the action potential is due to
a. calcium efflux
b. potassium efflux
c. chloride influx
d. potassium influx
e. sodium influx

ANS: E PTS: 1 DIF: Knowledge

12. The falling phase of the action potential is due to
a. calcium influx
b. potassium efflux
c. chloride influx
d. sodium efflux
e. the action of Na+-K+ pumps

ANS: B PTS: 1 DIF: Knowledge

13. Binding of an excitatory neurotransmitter to a postsynaptic neuron causes
a. voltage-gated Na+ channels open
b. voltage-gated K+ channels open
c. chemically-gated Na+ channels open
d. voltage-gated Cl- channels open
e. chemically-gated Cl- channels open

ANS: C PTS: 1 DIF: Comprehension

14. When chemically-gated Na+ channels open, the membrane
a. hyperpolarizes
b. repolarizes
c. depolarizes
d. becomes more negative
e. is inhibited

ANS: C PTS: 1 DIF: Knowledge

15. Opening either a chemically-gated Na+ channel or a chemically-gated K+ channel during the resting potential would cause
a. an impulse to be propagated
b. a graded potential
c. an action potential
d. the membranes potential to becomes more negative
e. threshold voltage will be reached

ANS: B PTS: 1 DIF: Comprehension

16. An action potential on a neuron develops when
a. threshold voltage is reached on an axon
b. voltage-gated Na+ channels open
c. spatial or temporal summation of graded potentials occurs to a great enough degree
d. the axon hillock reaches threshold voltage
e. any of the above events occur

ANS: E PTS: 1 DIF: Knowledge

17. Myelinated axons conduct impulses much faster because
a. the myelin insulates the axon
b. ion channels only have to open at the nodes
c. voltage is not lost along myelinated areas
d. saltatory conduction occurs
e. all of the above are true

ANS: E PTS: 1 DIF: Knowledge

18. At the peak of an action potential,
a. the diffusion of Na+ through voltage-gated channels ceases
b. the concentration gradient for K+ promotes the movement of this ion out of the cell
c. K+ permeability greatly increases
d. the electrical gradient promotes the diffusion of K+ out of the cell
e. all of the above are true

ANS: E PTS: 1 DIF: Comprehension

19. Which statement is not accurate about the absolute refractory period?
a. Another stimulus, regardless of its strength, cannot initiate another action potential during this period
b. During this period, voltage-gated Na+ channels open, then close but are inactivated
c. Immediately following this period, the membrane can experience another action potential if the stimulus is strong enough
d. This period occurs during the after hyperpolarization phase of the action potential
e. This period ensures a unidirectional spread of the action potential down a nerve fiber

ANS: D PTS: 1 DIF: Knowledge

20. Because of the presence of both activation and inactivation gates, voltage-gated Na+ channels can
a. be closed but capable of opening
b. be activated
c. be closed and not capable of opening
d. exhibit all of the above events
e. exhibit only the a and b events

ANS: D PTS: 1 DIF: Knowledge

21. What is responsible for development of the resting membrane potential?
a. Leak channels
b. Gated channels
c. Ion pumps
d. both a and b
e. both a and c

ANS: E PTS: 1 DIF: Knowledge

22. When is a plasma membrane more permeable to K+ than to Na+?
a. During the resting potential
b. During the rising phase of an action potential
c. During the rising phase of a graded potential
d. Both a and b
e. Both b and c

ANS: A PTS: 1 DIF: Knowledge

23. When the membrane potential is +15 mV, that portion of the membrane
a. is at the normal resting potential
b. has a positively-charged inside border
c. is more permeable to Ca2+ than normal
d. is in the after hyperpolarization phase of an action potential
e. is in a hyperpolarized state

ANS: B PTS: 1 DIF: Comprehension

24. Local current flow
a. occurs only on dendrites of neurons
b. causes impulses to move from the axon hillock toward the neurons cell body
c. involves current flowing between active and adjacent inactive areas, thereby bringing the inactive areas to threshold
d. occurs only on axons of neurons
e. does not occur on all excitable membranes

ANS: C PTS: 1 DIF: Knowledge

25. Saltatory conduction
a. occurs in unmyelinated nerve fibers
b. is slower than contiguous conduction because myelin acts as an insulator to slow the impulse
c. involves the impulse jumping from one node of Ranvier to the adjacent node
d. refers to the action potential spreading from one Schwann cell to the adjacent Schwann cell
e. occurs along dendrites and axons of certain neurons

ANS: C PTS: 1 DIF: Comprehension

26. Which statement is incorrect?
a. A local current can occur in myelinated nerve fibers
b. A local current flow from an active to an adjacent inactive area decreases the potential in the inactive area to threshold
c. Contiguous conduction occurs along Schwann cells on myelinated nerve fibers
d. Saltatory conduction is faster than contiguous conduction
e. A local current can occur in myelinated nerve fibers

ANS: C PTS: 1 DIF: Knowledge

27. Select the incorrect statement about the action potential.
a. It has an all-or-none characteristic
b. It has a refractory period
c. It is triggered by depolarization to threshold
d. It occurs along a plasma membrane
e. It speeds up transmission by summation

ANS: E PTS: 1 DIF: Knowledge

28. Permeability of which ion is affected by a positive feedback mechanism once threshold is reached?
a. sodium
b. potassium
c. calcium
d. chloride
e. protein

ANS: A PTS: 1 DIF: Knowledge

29. During the peak of the action potential, the membrane becomes most permeable to
a. sodium
b. potassium
c. calcium
d. chloride
e. protein

ANS: B PTS: 1 DIF: Knowledge

30. If a neuron were experimentally stimulated at both ends simultaneously, then
a. the action potentials would pass in the middle and travel to the opposite ends
b. the action potentials would meet in the middle and then be propagated back to their starting positions
c. the action potentials would stop as they met in the middle
d. the strongest action potential would override the weaker action potential
e. summation would occur when the action potentials met in the middle, resulting in a two larger action potentials traveling in opposite directions

ANS: C PTS: 1 DIF: Application

31. Which statement about graded potentials is false?
a. They are decremental.
b. They travel only short distances.
c. They are self-propagating.
d. They may contribute to the development of an action potential.
e. They travel in both directions along the membrane.

ANS: C PTS: 1 DIF: Knowledge

32. Which statement is true about the absolute refractory period?
a. It ensures that action potentials move in only one direction along a nerve fiber.
b. It is the period when the membrane can undergo another action potential, but only if the stimulus is strong enough.
c. It is the time during an action potential when voltage-gated Na+ channels are in their closed but capable of opening conformation.
d. places a lower limit on the frequency with which a neuron can conduct action potentials.
e. All of the above statements are true.

ANS: A PTS: 1 DIF: Knowledge

33. The period following an action potential during which a membrane cannot experience another action potential
a. is the absolute refractory period
b. occurs during the time after the Na+ gates have opened until they are restored to their closed but capable of opening state
c. prevents the action potential from spreading back over the part of the membrane where the impulse has just passed
d. includes the time when Na+ gates are in a closed and not capable of opening state
e. includes all of the above

ANS: E PTS: 1 DIF: Comprehension

34. The relative refractory period occurs after the action potential is complete because of
a. the lingering inactivation of the voltage-gated Na+ channels
b. the slowness of the voltage-gated K+ channels
c. the action of the sodium-potassium pumps
d. both a and b
e. both b and c

ANS: D PTS: 1 DIF: Knowledge

35. The trigger zone of a neuron
a. is located at the axon hillock
b. is located in the axon terminal
c. contains only chemically gated channels
d. conducts graded potentials to the axon
e. causes action potentials to move toward the cell body and dendrites

ANS: A PTS: 1 DIF: Knowledge

36. If neuron X is repeatedly stimulating neuron Z with an excitatory neurotransmitter, then
a. several simultaneous action potentials might be initiated on neuron Z
b. the membrane potential on neuron Z would increase
c. spatial summation would be occurring on neuron Z
d. the postsynaptic neuron in this situation would have to reach threshold voltage
e. none of the above would have to occur

ANS: E PTS: 1 DIF: Application

37.
Temporal summation on a postsynaptic neuron would occur when
a. a single presynaptic input causes two EPSPs to develop in rapid succession
b. an EPSP and an IPSP occur simultaneously and cancel each other out
c. two EPSPs develop simultaneously from different presynaptic inputs
d. two action potentials from two presynaptic inputs causes two action potentials to develop
e. none of the above take place

ANS: A PTS: 1 DIF: Knowledge

38. Spatial summation occurs on a postsynaptic neuron would occur when
a. several EPSPs from a single presynaptic input sum to reach threshold
b. EPSPs from several presynaptic inputs sum to reach threshold
c. there is simultaneous interaction of an EPSP and an IPSP
d. several IPSPs from a single presynaptic input sum to hyperpolarize the membrane
e. none of the above take place

ANS: B PTS: 1 DIF: Knowledge

39. At an excitatory synapse, an action potential in the presynaptic neuron increases
a. the membrane potential of the postsynaptic cell membrane
b. the permeability of the postsynaptic cell to Na+
c. the permeability of the postsynaptic cell to Cl-
d. the presynaptic neurons membrane potential
e. all of the above

ANS: B PTS: 1 DIF: Comprehension

40. At an inhibitory synapse, the postsynaptic membrane experiences
a. an increase in permeability to both Na+ and K+
b. an increase in membrane potential
c. hyperpolarization
d. an influx of cations
e. all of the above

ANS: B PTS: 1 DIF: Comprehension

41. An IPSP is
a. produced by increased permeability to Na+ and K+
b. produced by increased permeability to K+ or Cl-
c. a hyperpolarization of the presynaptic cell
d. a decrease in the postsynaptic membrane potential
e. an decrease in the presynaptic membrane potential

ANS: B PTS: 1 DIF: Knowledge

42. Which channel type is sensitive to serotonin?
a. voltage-gated
b. chemically-gated
c. mechanically-gated
d. acoustically-gated
e. none of these

ANS: B PTS: 1 DIF: Knowledge

43. Sequence the following events correctly.
1. Neurotransmitter diffuses across cleft.
2. Calcium induces exocytosis of neurotransmitter.
3. Permeability of postsynaptic membrane altered.
4. Ion channels open.
5. Neurotransmitter binds to receptor.

a. 1, 2, 3, 5, 4
b. 1, 4, 3, 2, 5
c. 2, 1, 5, 4, 3
d. 3, 1, 4, 5, 2
e. 5, 4, 3, 1, 2

ANS: C PTS: 1 DIF: Comprehension

44. Which statement is incorrect?
a. Inhibitory synapses cause postsynaptic hyperpolarization.
b. An inhibitory synapse may result in postsynaptic sodium channel opening.
c. An inhibitory synapse may result in increased postsynaptic potassium efflux.
d. An excitatory synapse causes depolarization of postsynaptic membranes.
e. An excitatory synapse increases sodium permeability.

ANS: B PTS: 1 DIF: Comprehension

45. Which statement is correct?
a. In presynaptic inhibition, another neuron inhibits an excitatory presynaptic input.
b. An IPSP depresses information fed into the cell from an inhibitory presynaptic input.
c. Not all axon terminals of an inhibitory neuron release inhibitory neurotransmitter.
d. During presynaptic inhibition, there is no change in presynaptic membrane potential.
e. An IPSP decreases the potential of the postsynaptic neuron.

ANS: A PTS: 1 DIF: Comprehension

46. Neuron A and neuron B release a minimal amount of neurotransmitter simultaneously onto neuron C, causing neuron C to experience an action potential. This is an example of
a. temporal summation
b. spatial summation
c. convergence
d. both a and c
e. both b and c

ANS: E PTS: 1 DIF: Application

47. The nucleus of a neuron is housed in the
a. axon
b. axon hillock
c. cell body
d. collaterals
e. dendrites

ANS: C PTS: 1 DIF: Knowledge

48. The normal direction for the movement of an action potential along part of a neuron is from
a. axon hillock to cell body
b. axon terminal to collateral axon
c. axon to dendrite
d. cell body to receptor
e. dendrite to cell body

ANS: E PTS: 1 DIF: Knowledge

49. With presynaptic inhibition,
a. an IPSP occurs on the postsynaptic cell
b. all excitatory information being fed into the cell is prevented
c. the release of excitatory neurotransmitter from a specific presynaptic excitatory input is depressed.
d. at least two of the above occur.
e. none of the above occur.

ANS: C PTS: 1 DIF: Knowledge

50. A hypothetical postsynaptic neuron has three presynaptic inputsX, Y, and Z. When X and Y are stimulated simultaneously, the postsynaptic neuron undergoes an action potential, yet when X and Z are stimulated simultaneously, there is no change in the postsynaptic neurons potential. What can you logically conclude?
a. Y and Z are both excitatory.
b. Y and Z are both inhibitory.
c. Y is excitatory and Z is inhibitory.
d. Y is inhibitory and Z is excitatory.
e. Not enough information to answer.

ANS: C PTS: 1 DIF: Application

51. The nodes of Ranvier are
a. action potential recordings
b. breaks in the myelin covering
c. spaces between neurons
d. specialized cells around axons
e. structures on axon terminals that release neurotransmitter

ANS: B PTS: 1 DIF: Knowledge

52. In divergence,
a. many presynaptic neurons synapse with one postsynaptic cell
b. one dendrite contacts many presynaptic neurons
c. action potentials initiated in the axon diminish as they spread to axon terminals
d. one axon synapses with many other cells
e. many axons spread out from one cell body

ANS: D PTS: 1 DIF: Knowledge

53. Which statement about a graded potential is false?
a. It can be a depolarization.
b. It can be a hyperpolarization.
c. It can be summated.
d. It has a refractory period.
e. It occurs in a specialized area of the membrane.

ANS: D PTS: 1 DIF: Knowledge

54. In convergence,
a. many presynaptic cells synapse with a single postsynaptic cell
b. one axon directly influences the activity of many other cells
c. many dendrites converge on one cell body
d. all of the above are true
e. none of the above are true

ANS: A PTS: 1 DIF: Knowledge

55. Neuromodulators
a. bind to receptors at synapses
b. contribute directly to EPSPs
c. contribute directly to IPSPs
d. may influence neurotransmitter production
e. speed up contiguous impulse conduction

ANS: D PTS: 1 DIF: Knowledge

56. Presynaptic facilitation results from
a. alteration of calcium permeability
b. continued generation of EPSPs
c. neuromodulator effects
d. increased neurotransmitter production
e. none of the above

ANS: A PTS: 1 DIF: Knowledge

57. Drugs may influence synaptic transmission by
a. altering the formation of neurotransmitters
b. blocking neurotransmitter reuptake
c. blocking receptors
d. blocking channels
e. all of the above

ANS: E PTS: 1 DIF: Knowledge

58. Select the last step for synaptic signaling when the action potential arrives at the axon terminal of a presynaptic neuron.
a. A neurotransmitter is released by exocytosis.
b. Calcium flows in the synaptic knob.
c. The neurotransmitter combines with a protein receptor on the subsynaptic membrane.
d. The permeability is altered in a postsynaptic neuron.
e. Sodium influx occurs at the axon terminals

ANS: D PTS: 1 DIF: Comprehension

59. Select the first step for synaptic signaling when the action potential arrives at the axon terminal of a presynaptic neuron.
a. A neurotransmitter is released by exocytosis.
b. Calcium flows into the synaptic knob.
c. The neurotransmitter combines with a protein receptor on the subsynaptic membrane.
d. The permeability is altered in a postsynaptic neuron.
e. The axon terminal depolarizes.

ANS: E PTS: 1 DIF: Comprehension

60. Select the neuropeptide.
a. acetylcholine
b. dopamine
c. epinephrine
d. cholecystokinin
e. glycine

ANS: D PTS: 1 DIF: Knowledge

61. Neuropeptides
a. are sometimes co-secreted along with classical neurotransmitters
b. are synthesized in the cytosol of the axon terminal
c. act at the subsynaptic membrane of the postsynaptic neuron
d. act slowly to bring about an IPSP or EPSP
e. are larger molecules than classical neurotransmitters

ANS: A PTS: 1 DIF: Knowledge

62. Tetanus toxin
a. binds with glycine receptors, thus blocking the action of this inhibitory neurotransmitter
b. destroys dopamine in the region of the brain involved in controlling complex movements
c. prevents the release of GABA that inhibits neurons that innervate skeletal muscle cells
d. promotes presynaptic facilitation
e. causes IPSPs to occur on skeletal muscle cell membranes

ANS: C PTS: 1 DIF: Knowledge

63. If neurotransmitter from X causes a slight hyperpolarization of a postsynaptic cell, then
a. the synapse is excitatory
b. the synapse is inhibitory
c. the postsynaptic cells membrane potential is becoming less negative
d. the postsynaptic cells membrane potential is becoming more positive
e. b, c, and d are occurring

ANS: B PTS: 1 DIF: Comprehension

64. If neuron X causes hyperpolarization, then what does it cause in a postsynaptic neuron?
a. Increased PNa+ and PK+
b. Increased PK+ or PCl-
c. Increased influx of protein anions
d. Increased permeability to calcium ions
e. Either b or c

ANS: B PTS: 1 DIF: Comprehension

65. If neurotransmitter from Y causes the membrane potential of the postsynaptic cell to decrease slightly, then
a. the synapse is excitatory
b. the postsynaptic membranes potential will be farther away from threshold
c. the postsynaptic membrane causes an EPSP on the presynaptic membrane
d. neurotransmitter from Y causes an IPSP on the presynaptic membrane
e. both a and c are correct

ANS: A PTS: 1 DIF: Comprehension

66. If neuron Ys neurotransmitter is causing neuron Xs membrane potential to decrease, then we would logically conclude that this neurotransmitter causes
a. increased PNa+ and PK+
b. increased PK+ or PCl-
c. increased permeability to protein anions
d. increased permeability to calcium ions
e. None of the above

ANS: A PTS: 1 DIF: Comprehension

67. If neuron X causes hyperpolarization of neuron Z but neuron Y causes depolarization of neuron Z, what change would you expect in neuron Z if it is stimulated by both X and Y simultaneously?
a. a significant increase in membrane potential
b. a significant decrease in membrane potential
c. temporal summation leading to an impulse on Z
d. simultaneous influx and efflux of cations or simultaneous influx of cations and efflux of anions
e. an increase in the resting membrane potential

ANS: D PTS: 1 DIF: Analysis

68. If an excitatory neuron and an inhibitory neuron both stimulate the same postsynaptic neuron simultaneously, what can you know for sure is happening in the postsynaptic neuron?
a. it would likely reach threshold
b. its permeability to cations and anions would decrease
c. its resting membrane potential would increase
d. it would be experiencing temporal summation
e. increased permeability to cations

ANS: E PTS: 1 DIF: Analysis

69. Which of the following is least related to a neuromodulator?
a. axonal transport
b. dense-core vesicle
c. cholecystokinin
d. synaptic vesicle
e. neuropeptide

ANS: D PTS: 1 DIF: Knowledge

70. Which of the following is least related to a description of contiguous conduction on a neuron?
a. dendrite
b. action potential
c. refractory period
d. unmyelinated axon
e. nondecremental propagation

ANS: A PTS: 1 DIF: Comprehension

71. When comparing saltatory conduction to contiguous conduction, saltatory conduction
a. is the only method that occurs along both dendrites and axons
b. is the only method that utilizes a positive feedback cycle
c. requires more Na+-K+ activity after repolarization is complete
d. causes the loss of fewer K+ ions during repolarization
e. occurs along unmyelinated axons

ANS: D PTS: 1 DIF: Knowledge

72. Which of the following characteristics is least related to steroid hormones?
a. Binds to intracellular receptor
b. Transported bound in the blood
c. May bind to hormone response element
d. Stimulate protein synthesis
e. Utilize a G protein

ANS: E PTS: 1 DIF: Comprehension

73. Which of the following is not true for lipophilic hormones?
a. Cells do not store them.
b. They are all derived from cholesterol.
c. They are bound to protein in the blood.
d. They typically activate genes.
e. Only a small portion of the hormone is biologically active.

ANS: B PTS: 1 DIF: Knowledge

74. Identify a second-messenger.
a. Insulin
b. G protein
c. G protein coupled receptor
d. Adenylyl cyclase
e. None of the above

ANS: E PTS: 1 DIF: Knowledge

75. All of the following may be considered second messengers except
a. inositol triphosphate
b. calcium ions
c. phosphodiesterase
d. cyclic AMP
e. diacylglycerol

ANS: C PTS: 1 DIF: Knowledge

TRUE/FALSE

1. Only neurons and muscle cells establish resting membrane potentials.

ANS: F PTS: 1 DIF: Knowledge

2. In a graded potential, the direction of current flow is designated by the movement of positive charges.

ANS: T PTS: 1 DIF: Knowledge

3. The passive current flow of a graded potential fades quickly.

ANS: T PTS: 1 DIF: Knowledge

4. The Na+ and K+ channels that open and close during an action potential are voltage-gated channels.

ANS: T PTS: 1 DIF: Knowledge

5. A spike is another name for the axon of a neuron.

ANS: F PTS: 1 DIF: Knowledge

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

ANS: F PTS: 1 DIF: Knowledge

7. After an action potential has occurred, there is more Na+ inside the cell than outside the cell (before any Na+-K+ pump activity has taken place).

ANS: F PTS: 1 DIF: Comprehension

8. During the resting potential, the membrane is more permeable to potassium ions than to sodium ions.

ANS: T PTS: 1 DIF: Knowledge

9. Action potentials can be summed.

ANS: F PTS: 1 DIF: Comprehension

10. Action potentials may result from hyperpolarization or depolarization.

ANS: F PTS: 1 DIF: Comprehension

11. For graded potentials, the magnitude of triggering is coded for in frequency rather than amplitude of depolarizations.

ANS: F PTS: 1 DIF: Knowledge

12. Schwann cells promote axonal growth, while oligodendrocytes inhibit it.

ANS: T PTS: 1 DIF: Knowledge

13. The refractory period limits the frequency of action potentials.

ANS: T PTS: 1 DIF: Knowledge

14. The diffusion of potassium ions reestablishes the resting membrane potential in a neuron immediately after it develops an action potential.

ANS: T PTS: 1 DIF: Knowledge

15. Local current flows locally between active and adjacent inactive areas of the cell membrane, thereby decreasing the potential in the inactive area to threshold.

ANS: T PTS: 1 DIF: Knowledge

16. Along a neuron, an action potential normally travels from the dendrites to the cell body to the axon.

ANS: F
Dendrites and cell bodies do not conduct action potentials.

PTS: 1 DIF: Knowledge

17. Nerve fiber is another name for a dendrite on a neuron.

ANS: F PTS: 1 DIF: Knowledge

18. The nodes of Ranvier are Schwann cells or oligodendrocytes that wrap themselves jelly roll fashion around the axon.

ANS: F PTS: 1 DIF: Knowledge

19. The myelin on a myelinated fiber in the peripheral nervous system is part of Schwann cells wrapped around the axon.

ANS: T PTS: 1 DIF: Knowledge

20. The myelin covering the axon promotes the leakage of ions from an axon, but it promotes conservation of ATP in the neuron.

ANS: F PTS: 1 DIF: Knowledge

21. The conduction velocity of a nerve impulse is slower in myelinated fibers than in unmyelinated fibers because myelin acts as an insulator that slows down the flow of current.

ANS: F PTS: 1 DIF: Knowledge

22. An unmyelinated fiber with a large diameter can conduct action potentials more rapidly than an unmyelinated fiber with a smaller diameter.

ANS: T PTS: 1 DIF: Knowledge

23. Myelinated fibers throughout the nervous system can regenerate when cut, but unmyelinated fibers cannot regenerate.

ANS: F PTS: 1 DIF: Knowledge

24. Oligodendrocytes form a regeneration tube to guide a regenerating nerve fiber to its proper destination.

ANS: F PTS: 1 DIF: Knowledge

25. Multiple sclerosis is an autoimmune disease in which the bodys defense system erroneously attacks the myelin sheath surrounding myelinated nerve fibers.

ANS: T PTS: 1 DIF: Knowledge

26. One strong stimulus can cause more than one action potential, but a weak stimulus may or may not generate an action potential.

ANS: F PTS: 1 DIF: Comprehension

27. Multiple sclerosis develops from a buildup of myelin of a neuron.

ANS: F PTS: 1 DIF: Knowledge

28. Cocaine blocks the binding of dopamine at postsynaptic membranes.

ANS: F PTS: 1 DIF: Knowledge

29. Oligodendrocytes are specialized to conduct electrical impulses to neurons.

ANS: F PTS: 1 DIF: Knowledge

30. Action potentials are initiated at the axon hillock region because it has the lowest threshold voltage.

ANS: T PTS: 1 DIF: Knowledge

31. The time following an action potential during which a membrane cannot respond to another stimulus, regardless of its strength, is called the relative refractory period.

ANS: F
Absolute refractory period

PTS: 1 DIF: Knowledge

32. The refractory period prevents action potentials from spreading back over the part of the membrane where the impulse has just passed.

ANS: T PTS: 1 DIF: Comprehension

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

ANS: F PTS: 1 DIF: Knowledge

34. During the absolute refractory period, the voltage-gated Na+ channels are not capable of opening again in response to another triggering event.

ANS: T PTS: 1 DIF: Knowledge

35. A stimulus that is too weak to depolarize the membrane to threshold produces an action potential that is weaker than normal.

ANS: F PTS: 1 DIF: Comprehension

36. G proteins in the plasma membrane of certain cells may become activated in response to the binding of water-soluble hormones, whereas protein phosphatases are continuously active in these cells.

ANS: T PTS: 1 DIF: Comprehension

37. Hormones derived from cholesterol are bound to proteins in the blood and primarily alter preexisting proteins via second-messenger systems.

ANS: F PTS: 1 DIF: Comprehension

38. A postsynaptic neuron can either excite or inhibit a presynaptic neuron.

ANS: F PTS: 1 DIF: Comprehension

39. Presynaptic inhibition is brought about when dendrites of a postsynaptic neuron alter the signals sent from an axon terminal of a presynaptic neuron.

ANS: F PTS: 1 DIF: Comprehension

40. A single neuron may be presynaptic to one group of neurons and postsynaptic to another group of neurons.

ANS: T PTS: 1 DIF: Comprehension

41. The tyrosine-kinase pathway is activated in response to certain lipophilic hormones, whereas the second messenger pathway is activated in response to certain hydrophilic hormones.

ANS: F PTS: 1 DIF: Comprehension

42. Increased permeability of the postsynaptic cell to Cl- lessens the likelihood that the postsynaptic cell will undergo an action potential.

ANS: T PTS: 1 DIF: Comprehension

43. Amplification is a phenomenon associated with hormones derived from cholesterol.

ANS: F PTS: 1 DIF: Comprehension

44. A given synapse may produce EPSPs at one time and IPSPs at another time.

ANS: F PTS: 1 DIF: Knowledge

45.
A lipophilic chemical messenger uses a second messenger system to alter the activity of a target cell.

ANS: F PTS: 1 DIF: Comprehension

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

ANS: T PTS: 1 DIF: Comprehension

47. Common second messengers include cAMP, acetylcholine, and calcium ions.

ANS: F PTS: 1 DIF: Knowledge

48. cAMP and phospholipase are more closely associated with the action of water-soluble hormones than with the action of lipid-soluble hormones.

ANS: T PTS: 1 DIF: Comprehension

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

ANS: T PTS: 1 DIF: Knowledge

50. Most endocrine glands secrete paracrine substances that function as neurohormones.

ANS: F PTS: 1 DIF: Comprehension

51. Neuropeptides are mainly neuromodulators that function as second messengers in cells that respond to hydrophilic hormones.

ANS: F PTS: 1 DIF: Comprehension

52. The grand postsynaptic potential depends on the sum of activity of the presynaptic inputs.

ANS: T PTS: 1 DIF: Comprehension

53. Adenylyl cyclase and diacylglycerol are more associated with hydrophilic hormones than with lipophilic hormones.

ANS: T PTS: 1 DIF: Comprehension

54. Divergence refers to the neuronal arrangement wherein the dendrites diverge to synapse with as many presynaptic inputs as possible.

ANS: F PTS: 1 DIF: Knowledge

55. Classical neurotransmitters and neuropeptides are sometimes co-secreted from the same axon terminal.

ANS: T PTS: 1 DIF: Knowledge

56. CaM is more closely associated with lipophilic hormones than with hydrophilic hormones.

ANS: F PTS: 1 DIF: Comprehension

57. Amplification is more closely associated with hydrophilic hormones than with lipophilic hormones.

ANS: T PTS: 1 DIF: Comprehension

58. Cholera toxin is more disruptive to the action of hydrophilic hormones than to the action of lipophilic hormones.

ANS: T PTS: 1 DIF: Comprehension

59. Preprohormones give rise to lipophilic hormones.

ANS: F PTS: 1 DIF: Knowledge

60. Thyroid hormone is derived from an amino acid, which makes it soluble in water and able to utilize a second messenger system.

ANS: F PTS: 1 DIF: Knowledge

COMPLETION

Complete each of the following statements.

1. The resting membrane potential of a typical nerve cell is about ____________________ millivolts.

ANS: -70

PTS: 1 DIF: Knowledge

2. A plasma membrane is polarized if it separates particles with an opposite ____________________.

ANS: charge

PTS: 1 DIF: Knowledge

3. At ____________________ potential, typically around -55 mv, rapid depolarization occurs.

ANS: threshold

PTS: 1 DIF: Knowledge

4. Opening channels that allow ____________________ ions or ____________________ ions result in depolarization of the plasma membrane.

ANS: Na+, Ca2+

PTS: 1 DIF: Comprehension

5. ____________________ is the hindrance to electrical charge movement.

ANS: Resistance

PTS: 1 DIF: Knowledge

6. The chemical called ____________________ along axons reduces resistance and, hence, increases impulse velocity.

ANS: myelin

PTS: 1 DIF: Knowledge

7. At the end of repolarization, the newly opened channels for ____________________ ions close.

ANS: K+

PTS: 1 DIF: Knowledge

8. A neuron starts to depolarize when _________________ ions move into the cell.

ANS: sodium

PTS: 1 DIF: Comprehension

9. A single nerve cell, also called a ____________________, typically consists of the following three basic parts: ____________________, ____________________, and ____________________.

ANS: neuron, cell body, dendrites, axon

PTS: 1 DIF: Knowledge

10. The ____________________ or ____________________ of a neuron is a single, elongated tubular process that conducts action potentials away from the cell body and eventually terminates at other cells.

ANS: axon, nerve fiber

PTS: 1 DIF: Knowledge

11. The longest part of a typical neuron is the ____________________.

ANS: axon or nerve fiber

PTS: 1 DIF: Knowledge

12. During the resting membrane potential, the inside of a neuron has a net ____________________ charge.

ANS: negative

PTS: 1 DIF: Knowledge

13. An increase in the size of the ____________________ of a nerve fiber, along with the amount of ____________________ around the fiber both increase its rate of conduction.

ANS: diameter, myelin

PTS: 1 DIF: Knowledge

14. An action potential in a presynaptic neuron induces opening of voltage-gated ____________________ channels in the synaptic knob, which triggers exocytosis of synaptic vesicles.

ANS: Ca++

PTS: 1 DIF: Knowledge

15. ____________________ cells form myelin around neurons in the PNS, whereas ____________________ form myelin around neurons in the CNS.

ANS: Schwann, oligodendrocytes

PTS: 1 DIF: Knowledge

16. Myelinated fibers conduct impulses about ____________________ times faster than unmyelinated fibers of the same diameter.

ANS: 50

PTS: 1 DIF: Knowledge

17. ____________________-soluble hormones must use ____________________ systems to exert their effects on target cells.

ANS: Water, second-messenger

PTS: 1 DIF: Comprehension

18. ____________________ are chemical messengers that bind to neuronal receptors at nonsynaptic sites and alter the effectiveness of ongoing synaptic activity.

ANS: Neuromodulators

PTS: 1 DIF: Knowledge

19. When EPSPs occurring simultaneously from two different presynaptic inputs add together or sum to bring the postsynaptic cell to threshold, it is called ____________________ summation.

ANS: spatial

PTS: 1 DIF: Knowledge

20. Schwann cells stimulate the formation of a(n) ____________________ tube to rebuild damaged neurons.

ANS: regeneration

PTS: 1 DIF: Knowledge

21. When EPSPs originating from a single presynaptic input occur so close together in time that they add together or sum, thereby bringing the postsynaptic cell to threshold, it is called ____________________ summation.

ANS: temporal

PTS: 1 DIF: Knowledge

22. The neuronal relationship where a single presynaptic cell branches to terminate on many other cells is called ____________________.

ANS: divergence

PTS: 1 DIF: Knowledge

23. The neuronal relationship where many presynaptic cells terminate on a single postsynaptic cell is called ____________________.

ANS: convergence

PTS: 1 DIF: Knowledge

24. Opening a chemically-gated ____________________ channel or ____________________ channel will increase the membrane potential of a plasma membrane.

ANS: K+, Cl-

PTS: 1 DIF: Comprehension

25. ____________________ are local chemical messengers that exert an effect only on neighboring cells in the immediate environment.

ANS: Paracrines

PTS: 1 DIF: Knowledge

26. ____________________ are chemical messengers that do not cause the formation of EPSPs or IPSPs but rather bring about long-term changes that depress or enhance the action of the synapse.

ANS: Neuromodulators

PTS: 1 DIF: Knowledge

27. One presynaptic neuron can only produce ____________________ summation on a postsynaptic neuron.

ANS: temporal

PTS: 1 DIF: Comprehension

28. ____________________ 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.

ANS: Neuromodulators, neurotransmitters

PTS: 1 DIF: Knowledge

29. Axon terminals possess ____________________ voltage-gated channels that when operational induce neurotransmitter release.

ANS: calcium

PTS: 1 DIF: Knowledge

30. ____________________ are released into the blood by neurosecretory neurons.

ANS: Neurohormones

PTS: 1 DIF: Knowledge

31. ____________________ is a second messenger formed when a membrane enzyme called a cyclase becomes activated by a G protein.

ANS: cAMP

PTS: 1 DIF: Knowledge

32. The process by which incoming signals are conveyed into a target cell, where they are transformed into a certain cellular response is called signal _________.

ANS: transduction

PTS: 1 DIF: Knowledge

33. In a second messenger system, the first messenger is the __________.

ANS: hormone

PTS: 1 DIF: Knowledge

34. For a neuron, the axon is its _______ zone and an axon terminal is its ______ zone.

ANS: conducting, output

PTS: 1 DIF: Knowledge

MATCHING

Indicate the direction that the force in question tends to move the involved ion under the stated conditions by writing the appropriate letter in the blank, using the following answer code:
a. tends to move the involved ion out of the cell
b. tends to move the involved ion into the cell

1. Concentration gradient for Na+ at threshold potential

2. Electrical gradient for Na+ at threshold potential

3. Concentration gradient for K+ at the peak of an action potential

4. Electrical gradient for K+ at the peak of an action potential

5. Concentration gradient for Na+ at the end of an action potential

6. Concentration gradient for K+ at the end of an action potential

1. ANS: B PTS: 1 DIF: Comprehension

2. ANS: B PTS: 1 DIF: Comprehension

3. ANS: A PTS: 1 DIF: Comprehension

4. ANS: A PTS: 1 DIF: Comprehension

5. ANS: B PTS: 1 DIF: Comprehension

6. ANS: A PTS: 1 DIF: Comprehension

Indicate whether the membrane is more permeable to K+ or to Na+ or is equally permeable to these ions under the stated conditions:
a. more permeable to K+ than to Na+
b. more permeable to Na+ than to K+
c. equally permeable to Na+ and K+

7. During the rising phase of an action potential

8. During the falling phase of an action potential

9. At resting potential

10. During an EPSP

11. During an IPSP

7. ANS: B PTS: 1 DIF: Comprehension

8. ANS: A PTS: 1 DIF: Comprehension

9. ANS: A PTS: 1 DIF: Comprehension

10. ANS: B PTS: 1 DIF: Comprehension

11. ANS: A PTS: 1 DIF: Comprehension

Choose the match for each substance listed.
a. covering on the axon
b. second messenger
c. branching process from a cell body
d. impulse-conducting region
e. junction between neurons
f. neurotransmitter

12. Acetylcholine

13. Axon

14. Dendrite

15. Myelin

16. Synapse

12. ANS: F PTS: 1 DIF: Knowledge

13. ANS: D PTS: 1 DIF: Knowledge

14. ANS: C PTS: 1 DIF: Knowledge

15. ANS: A PTS: 1 DIF: Knowledge

16. ANS: E PTS: 1 DIF: Knowledge

Use the answer code below to answer this section.
a. increased PNa+ and no change in PK+
b. decreased PNa+ and decreased PK+
c. increased PK+ and no change in PNa+
d. increased PK+ and increased PNa+
e. increased PK+ and decreased PNa+
f. Na influx
g. Na+ efflux
h. K+ influx
i. K+ efflux

17. Permeability changes at threshold voltage

18. Permeability changes that occur at the peak of an action potential

19. Permeability changes at the start of an IPSP

20. Ion movement responsible for the rising phase of the action potential

21. Ion movement responsible for the falling phase of the action potential

22. Ion movement that would cause an EPSP

23. Ion movement that would cause an IPSP

17. ANS: A PTS: 1 DIF: Comprehension

18. ANS: E PTS: 1 DIF: Comprehension

19. ANS: C PTS: 1 DIF: Comprehension

20. ANS: F PTS: 1 DIF: Comprehension

21. ANS: H PTS: 1 DIF: Comprehension

22. ANS: F PTS: 1 DIF: Comprehension

23. ANS: I PTS: 1 DIF: Comprehension

Indicate the relationship between the two items listed in each situation:
a. A is greater than B.
b. B is greater than A.
c. A and B are equal.

24. A. Resting neurons permeability to K+
B. Resting neurons permeability to Na+

25. A. Neurons permeability to Na+ during the rising phase of an action potential
B. Neurons permeability to K+ during the rising phase of an action potential

26. A. Resting neurons permeability to Na+
B. Neurons permeability to Na+ during the rising phase of an action potential

27. A. Resting neurons permeability to K+
B. Neurons permeability to K+ during the falling phase of an action potential

28. A. Neurons permeability to Na+ during the falling phase of an action potential
B. Neurons permeability to K+ during the falling phase of an action potential

29. A. Na+ concentration in the neurons cytosol immediately before an action potential
B. Na+ concentration in the neurons cytosol immediately following an action potential

30. A. K+ concentration in the neurons cytosol immediately before an action potential
B. K+ concentration in the neurons cytosol immediately following an action potential

31. A. Na+ concentration in the extracellular fluid
B. Na+ concentration in the neurons cytosol immediately following an action potential

32. A. Resting membrane potential
B. Potential during hyperpolarization

33. A. Resting membrane potential
B. Potential during depolarization

24. ANS: A PTS: 1 DIF: Evaluation

25. ANS: A PTS: 1 DIF: Evaluation

26. ANS: B PTS: 1 DIF: Evaluation

27. ANS: B PTS: 1 DIF: Evaluation

28. ANS: B PTS: 1 DIF: Evaluation

29. ANS: B PTS: 1 DIF: Evaluation

30. ANS: A PTS: 1 DIF: Evaluation

31. ANS: A PTS: 1 DIF: Evaluation

32. ANS: B PTS: 1 DIF: Evaluation

33. ANS: A PTS: 1 DIF: Evaluation

Indicate whether an excitatory or inhibitory synapse is being described.
a. excitatory synapse
b. inhibitory synapse

34. Small hyperpolarization of the postsynaptic neuron

35. Small depolarization of the postsynaptic neuron

36. Increased PNa+ and increased PK+ of the subsynaptic membrane

37. Increased PCl- of the subsynaptic membrane

38. Increased PK+ of the subsynaptic membrane (no change in PNa+)

34. ANS: B PTS: 1 DIF: Comprehension

35. ANS: A PTS: 1 DIF: Comprehension

36. ANS: A PTS: 1 DIF: Comprehension

37. ANS: B PTS: 1 DIF: Comprehension

38. ANS: B PTS: 1 DIF: Comprehension

Assume that a hypothetical neuron has three presynaptic inputs: A and B are excitatory, and C is inhibitory. Indicate which of the following changes will take place.
a. no change in potential of the postsynaptic cell
b. spatial summation
c. temporal summation

39. What would occur if presynaptic neuron B were fired rapidly?

40. What would occur if both presynaptic neurons A and B were fired simultaneously?

41. What would occur if both presynaptic neurons A and C were fired simultaneously?

39. ANS: C PTS: 1 DIF: Comprehension

40. ANS: B PTS: 1 DIF: Comprehension

41. ANS: A PTS: 1 DIF: Comprehension

Indicate which characteristic applies to classical neurotransmitters and neuropeptides.
a. neurotransmitters
b. neuropeptides
c. both neurotransmitters and neuropeptides
d. neither neurotransmitters nor neuropeptides

42. Released from axon terminal

43. Synthesized in cytosol of synaptic knob

44. Large: 2 to 40 amino acids in length

45. Small: one amino acid or similar chemical

46. Usually open specific ion channels

47. Usually function as neuromodulators

48. Released into blood for delivery to target

42. ANS: C PTS: 1 DIF: Knowledge

43. ANS: A PTS: 1 DIF: Knowledge

44. ANS: B PTS: 1 DIF: Knowledge

45. ANS: A PTS: 1 DIF: Knowledge

46. ANS: A PTS: 1 DIF: Knowledge

47. ANS: B PTS: 1 DIF: Knowledge

48. ANS: D PTS: 1 DIF: Knowledge

Match neural disease/influence with correct characteristic.
a. multiple sclerosis
b. tetanus
c. strychnine
d. roseola
e. Parkinsons disease

49. May predispose a person to multiple sclerosis

50. Prevents release of GABA

51. Destroys myelin

52. Due to insufficient dopamine

53. Competes with glycine for receptors

49. ANS: D PTS: 1 DIF: Knowledge

50. ANS: B PTS: 1 DIF: Knowledge

51. ANS: A PTS: 1 DIF: Knowledge

52. ANS: E PTS: 1 DIF: Knowledge

53. ANS: C PTS: 1 DIF: Knowledge

ART-BASED QUESTIONS

Use these figures to answer the corresponding questions.

1. The structure labeled 1 is
a. part of a chemically-gated channel
b. part of a mechanically-gated channel
c. the activation gate of a Na+ channel
d. part of a chemically-gated channel and the inactivation gate of a Na+ channel
e. none of these

ANS:
e

PTS: 1 DIF: Knowledge

2. Which number identifies the structure that is primarily responsible for the absolute refractory period during an action potential?
a. 1
b. 2
c. 3
d. 4
e. None of the above

ANS:
a

PTS: 1 DIF: Evaluation

3. The structure labeled 4 is
a. part of a channel that allows Na+ ions to diffuse into the ECF
b. the activation gate for a gated K+ channel
c. the inactivation gate for a gated Na+ channel
d. part of a second messenger system
e. the activation gate for a gated K+ channel and part of a second messenger system

ANS:
b

PTS: 1 DIF: Knowledge

Use this figure to answer the corresponding questions.

4. This figure shows
a. the mechanism by which some lipid-soluble hormones affect their target cells
b. the way insulin affects certain cells
c. the method in which IP3 forms
d. a common second messenger system for hormone that is derived from cholesterol
e. none of these

ANS:
b

PTS: 1 DIF: Comprehension

5. Label 3 is
a. a second messenger
b. a kinase protein
c. a G protein
d. a G protein coupled receptor
e. an effector enzyme

ANS:
e

PTS: 1 DIF: Comprehension

6. A second messenger is labeled
a. 1
b. 2
c. 3
d. 4
e. 5

ANS:
d

PTS: 1 DIF: Comprehension

ESSAY

1. Describe an action potential and explain why a region of the membrane that is in the absolute refractory period cannot experience another action potential until repolarization is complete. Include the following in your answer: voltage-gated Na+ channels, voltage-gated K+ channels, activation gate, inactivation gate, threshold voltage, increasing membrane potential, and decreasing membrane potential.

ANS:
When a voltage-gated Na+ channel is at rest, its inactivation gate is open and its activation gate is closed. When threshold voltage is reached, the activation gate opens and allows Na+ ions to diffuse into the cell; this action decreases the membrane potential to the point that the potential becomes positive. At the peak of the depolarization event, the activation and inactivation gates in the Na+ channels close, but the voltage-gated K+ channels open. As K+ ions diffuse out of the cell, the membrane potential increases; i.e., the membrane repolarizes. The inactivation gate in the Na+ channels will remain shut until the membrane potential has been completely repolarized. After repolarization, the inactivation gate will reopen. Now the membrane can respond to another stimulus.

PTS: 1 DIF: Comprehension

2. How does a depolarizing graded potential lead to the propagation of action potentials?

ANS:
A depolarizing graded potential does not reverse the polarity of the cell membrane, but it moves the potential closer to threshold voltage. If threshold voltage is reached, voltage-gated Na+ channels in that region will open, causing an action potential in which the inside border of the membrane becomes positive. This reversal in polarity causes the membrane potential in the adjacent region to reach threshold, which causes voltage-gated Na+ channels in that region to open. Thus, an action potential in one region will change the voltage in an adjacent region significantly enough to generate an action potential there. This process continues and allows the action potentials to be propagated along the plasma membrane.

PTS: 1 DIF: Knowledge

3. What might happen on a postsynaptic neuron if, at the same time, it receives one stimulus at an excitatory synapse located close to the axon hillock but receives two stimuli at two different inhibitory synapses, both of which are far away from the axon hillock?

ANS:
Since graded potentials diminish in intensity as they travel across a membrane, the closer to the axon hillock the stimulus is applied, the greater its effect. Therefore, one excitatory stimulus generating an EPSP near the axon hillock may be intense enough to reach threshold and initiate an action potential on the postsynaptic neuron, because the two IPSPs generated by the inhibitory neurons diminish as they move toward the axon hillock and may not be able to counteract the one EPSP generated near the hillock.

PTS: 1 DIF: Application

4. Neuron A is excitatory to neuron B. Describe three ways that the nervous system might prevent neuron B from experiencing an action potential.

ANS:
(1) Neuron A is not stimulated; therefore, it will not generate EPSPs on neuron B.
(2) Neuron A is actively inhibited by the formation of IPSPs on its dendrites and cell body; therefore, action potentials are not generated at As axon hillock.
(3) Neuron A sends an impulse along its axon, but another neuron inhibits the release of neurotransmitter from As axon terminal; this is presynaptic inhibition and no EPSPs are generated on B.

PTS: 1 DIF: Evaluation

5. What are four ways in which drugs might influence the nervous system at the neuronal level?

ANS:
A drug or disease agent might:(1) alter the synthesis, transport, storage, or release of a neurotransmitter; (2) modify the way in which the neurotransmitter interacts with the postsynaptic receptor; (3) influence the neurotransmitters reuptake or destruction; and (4) replace or substitute for a deficient neurotransmitter.

PTS: 1 DIF: Application

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