Animal Physiology, Chapter 12: Neurons PDF

Test Bank to accompany Animal Physiology, Fourth Edition Hill Wyse Anderson Chapter 12: Neurons TEST BANK QUESTIONS Multiple Choice 1. Init...

Test Bank to accompany Animal Physiology, Fourth Edition Hill Wyse Anderson Chapter 12: Neurons TEST BANK QUESTIONS Multiple Choice 1. Initiation of the action potential usually occurs _______ of the neuron. a. in the cell body b. on the dendrites c. at the axon initial segment d. on the axon Answer: c Textbook Reference: The Physiology of Control: Neurons and Endocrine Cells Compared Bloom’s Category: 1. Remembering 2. Which statement about an animal’s nervous system is true? a. Neurotransmitter is released throughout the body via the blood. b. Signal transmission rate is relatively slow. c. Neurons form highly discrete lines of communication. d. Action potential signals degrade over distance. Answer: c Textbook Reference: The Physiology of Control: Neurons and Endocrine Cells Compared Bloom’s Category: 2. Understanding 3. For a hormone to elicit a specific response from a cell, the cell must possess a. a synapse. b. a cell body. c. dendrites specific to the hormone. d. receptor proteins specific to the hormone. Answer: d Textbook Reference: The Physiology of Control: Neurons and Endocrine Cells Compared Bloom’s Category: 2. Understanding 4. Which statement about the startle response of the cockroach is true? a. Vibrations of hairs generate nerve impulses in sensory neurons. b. Sound waves or air currents synapse with the filiform hairs. c. Sensory neurons synapse with and excite the dorsal hollow spinal cord. © 2016 Sinauer Associates, Inc. d. At the metathoracic ganglion, the interneurons synaptically inhibit leg motor neurons. Answer: a Textbook Reference: Neurons Are Organized into Functional Circuits in Nervous Systems Bloom’s Category: 5. Evaluating 5. Which glial cells are found in the peripheral nervous system? a. Oligodendrocytes b. Schwann cells c. Astrocytes d. Microglial cells Answer: b Textbook Reference: The Cellular Organization of Neural Tissue Bloom’s Category: 1. Remembering 6. Which statement about glial cells is true? a. They integrate cell membrane potentials to enhance or inhibit action potentials. b. They decrease the velocity of nerve-impulse propagation. c. They help supply metabolic substrates to neurons. d. They act as metabolic intermediaries between epithelial cells and neurons. Answer: c Textbook Reference: The Cellular Organization of Neural Tissue Bloom’s Category: 2. Understanding 7. The separation of positive and negative charges constitutes a. resistance. b. an electric current. c. a voltage. d. capacitance. Answer: c Textbook Reference: The Ionic Basis of Membrane Potentials Bloom’s Category: 1. Remembering 8. Which statement about membrane capacitance is true? a. It is in series with membrane resistance. b. In a cell, the membrane separates only similarly charged ions. c. It is measured in ohms. d. It is a function of the permeability of the membrane. Answer: a Textbook Reference: The Ionic Basis of Membrane Potentials Bloom’s Category: 2. Understanding 9.–10. Refer to the figure below. © 2016 Sinauer Associates, Inc. 9. What is occurring at the membrane? a. Depolarization b. Hyperpolarization c. Increase in resistance d. Decrease in capacitance Answer: a Textbook Reference: The Ionic Basis of Membrane Potentials Bloom’s Category: 4. Analyzing 10. In the lower panel, the difference between the dashed line and the solid red line is due to a. membrane resistance. b. the fact that one represents a depolarization and the other represents a hyperpolarization. c. the capacitive properties of the membrane. d. the difference in applied voltage. Answer: c Textbook Reference: The Ionic Basis of Membrane Potentials Bloom’s Category: 4. Analyzing 11.–13. Refer to the figure below. © 2016 Sinauer Associates, Inc. 11. In the figure, the _______ decreases with distance. a. graded potential b. action potential c. membrane current d. membrane capacitance Answer: a Textbook Reference: The Ionic Basis of Membrane Potentials Bloom’s Category: 4. Analyzing 12. Which statement offers the best explanation for the difference between the middle panel and the lower panel? a. The membrane in the lower panel is producing a lower current. b. There is a lower resistance in the lower panel at the point where voltage is measured. c. There is a greater capacitance in the lower panel at the point where voltage is measured. d. The membrane voltage measured in the lower panel is farther away from the current pulse. Answer: d Textbook Reference: The Ionic Basis of Membrane Potentials Bloom’s Category: 4. Analyzing 13. The properties shown in the figure can be measured in a. neurons. b. neurons and pacemaker cells. c. muscle cells. d. neurons, pacemaker cells, and muscle cells © 2016 Sinauer Associates, Inc. Answer: d Textbook Reference: The Ionic Basis of Membrane Potentials Bloom’s Category: 4. Analyzing 14. Which variable does not contribute to the passive electrical properties of a cell? a. Membrane resistance b. Membrane capacitance c. The resting membrane current d. The time constant Answer: c Textbook Reference: The Ionic Basis of Membrane Potentials Bloom’s Category: 4. Analyzing 15.–16. Refer to the figure below. 15. The figure shows that the membrane potential results from a. the six pairs of ions sitting on the membrane. b. the thousands of ions sitting on the membrane. c. the overall difference intra- and extra cellular ion concentrations in the volume of cell shown. d. movement of ions across the cell membrane. Answer: a Textbook Reference: The Ionic Basis of Membrane Potentials Bloom’s Category: 3. Applying 16. In the figure, _______in the center of the cell. a. there would be a slight negative charge © 2016 Sinauer Associates, Inc. b. there would be a strong negative charge c. the overall charge neutrality would be maintained independently of the membrane potential d. there would be a slight positive charge Answer: c Textbook Reference: The Ionic Basis of Membrane Potentials Bloom’s Category: 4. Analyzing 17. Which characteristic is not a factor in the Nernst Equation? a. Capacitance b. Temperature c. The valence of the ion species d. The ion concentrations on the two sides of the membrane Answer: a Textbook Reference: The Ionic Basis of Membrane Potentials Bloom’s Category: 4. Analyzing 18. In a cell, the difference in ion concentration between the intracellular and extracellular fluids results from a. active ion transport. b. passive diffusion of ions. c. bulk movements of intracellular and extracellular fluids. d. both active ion transport and passive diffusion of ions. Answer: d Textbook Reference: The Ionic Basis of Membrane Potentials Bloom’s Category: 2. Understanding 19. According to the Nernst equation, which change will depolarize Vm, the membrane potential? a. A decrease in temperature b. An increase in the valence of the ion species involved c. A decrease in the concentration of anions inside the membrane d. A decrease in the electromotive force of the ion Answer: c Textbook Reference: The Ionic Basis of Membrane Potentials Bloom’s Category: 3. Applying 20. Which statement regarding the ions in intracellular and extracellular fluids in a standard animal cell is true? a. Na+ leaks into the cell rapidly because its electrochemical gradient is large. b. K+ leaks out of the cell slowly because the electrochemical gradient is small. c. Cl– leaks into the cell rapidly because its electrochemical gradient is large. d. Negatively charged proteins leak out of the cell slowly because their electrochemical gradient is small. Answer: b Textbook Reference: The Ionic Basis of Membrane Potentials © 2016 Sinauer Associates, Inc. Bloom’s Category: 2. Understanding 21. According to the Goldman equation, the contribution of each ion to the membrane potential depends most on a. its size. b. its membrane permeability. c. its activation energy. d. the resting membrane potential. Answer: b Textbook Reference: The Ionic Basis of Membrane Potentials Bloom’s Category: 2. Understanding 22. Which structure is most responsible for the all-or-none property of the action potential? a. Myelin b. Voltage-gated K+ channels c. Voltage-gated Na+ channels d. Leakage of K+ channels Answer: c Textbook Reference: The Action Potential Bloom’s Category: 2. Understanding 23.–26. Refer to the figure below. © 2016 Sinauer Associates, Inc. 23. Which arrow best represents the point where permeability to sodium is the highest? a. I b. II c. III d. IV Answer: a Textbook Reference: The Action Potential Bloom’s Category: 4. Analyzing 24. Which arrow best represents the point where the voltage-gated sodium channels are inactivated? a. I b. III c. IV d. III and IV Answer: d Textbook Reference: The Action Potential Bloom’s Category: 4. Analyzing 25. _______ channels are responsible for the undershoot at point D of the figure. a. Voltage-gated sodium b. Voltage-gated potassium c. Ligand-gated potassium d. Voltage-gated calcium Answer: b Textbook Reference: The Action Potential Bloom’s Category: 4. Analyzing 26. What occurs when the membrane is clamped at –100 mV? a. Voltage-gated ion channels behave in a similar manner as in the diagram. b. Voltage-gated ion channels do not open at all. c. There is a brief shift in ions and then a flat current at –100 mV. d. Only ligand-gated channels work at this point. Answer: b Textbook Reference: The Action Potential Bloom’s Category: 3. Applying 27.–29. Refer to the figure below. © 2016 Sinauer Associates, Inc. 27. How many separate current pulses cause the membrane potential to reach the threshold? a. 1 b. 2 c. 3 d. 5 Answer: c Textbook Reference: The Action Potential Bloom’s Category: 4. Analyzing 28. What would likely occur if stimulus 3 and 6 were performed simultaneously? a. An action potential would likely occur. b. An action potential would likely not occur. c. Multiple action potentials would likely occur. d. The threshold voltage would likely decrease. Answer: b Textbook Reference: The Action Potential Bloom’s Category: 4. Analyzing 29. If stimulating current pulse 9 (not shown) was both stronger and longer than stimulating current pulse 8, then a. the train of action potentials would continue for the length of the stimulating current. b. action potentials would increase in amplitude. c. action potentials would first increase in frequency and then decrease. d. the line at stimulus 9 would look exactly same as the line at stimulus 8. Answer: a Textbook Reference: The Action Potential Bloom’s Category: 4. Analyzing 30. For an axon at resting membrane potential, the K+ leak channel is _______, the voltage-gated Na+ channel is _______, and the voltage-gated K+ channel is _______. a. open; inactivated; closed b. closed; inactivated; closed © 2016 Sinauer Associates, Inc. c. open; inactivated; open d. open; closed; closed Answer: d Textbook Reference: The Action Potential Bloom’s Category: 2. Understanding 31. During the falling phase of an action potential, the K+ leak channel on the axon is _______, the voltage-gated Na+ channel is _______, and the voltage-gated K+ channel is _______. a. open; inactivated; closed b. closed; inactivated; closed c. open; inactivated; open d. open; closed; closed Answer: c Textbook Reference: The Action Potential Bloom’s Category: 2. Understanding 32.–34. Refer to the figure below. © 2016 Sinauer Associates, Inc. 32. Which technique was used to collect the data in the bottom panel? a. Patch-clamp b. Voltage-clamp c. Current-clamp d. Hodgkin clamp Answer: a Textbook Reference: The Action Potential Bloom’s Category: 4. Analyzing 33. On the figure, I represents _______ currents through voltage-gated _______ channels. a. outward; Na+ b. inward; Na+ c. outward; K+ © 2016 Sinauer Associates, Inc. d. inward; K+ Answer: b Textbook Reference: The Action Potential Bloom’s Category: 4. Analyzing 34. Why do the channels at II on the figure stay open longer than those at I? a. Channels at I are responding to a depolarization, whereas channels at II are responding to a hyperpolarization. b. The depolarization is a faster event compared to the repolarization. c. Channels at I are less sensitive to voltage compared to channels at II. d. Channels at I become inactivated, whereas channels at II close due to membrane voltage. Answer: d Textbook Reference: The Action Potential Bloom’s Category: 4. Analyzing 35.–37. Refer to the figure below: 35. Which technique was used to collect the data shown in the figure? a. Patch-clamp b. Hodgkin clamp c. Current-clamp d. Voltage-clamp Answer: d Textbook Reference: The Action Potential Bloom’s Category: 4. Analyzing 36. The treatment difference between the membranes shown in the graphs is that the membrane on the left is being _______, while the membrane on the right is being _______. a. depolarized; depolarized in Na+-free seawater b. hyperpolarized; hyperpolarized in an isoionic Na+ solution c. hyperpolarized; depolarized d. depolarized; hyperpolarized © 2016 Sinauer Associates, Inc. Answer: c Textbook Reference: The Action Potential Bloom’s Category: 4. Analyzing 37. How would the trace on the right look if the neuron was soaking in TEA? a. The inward ionic current would disappear. b. The outward ionic current would disappear. c. The trace would look exactly like the trace in the left panel. d. The outward ionic current would be amplified. Answer: b Textbook Reference: The Action Potential Bloom’s Category: 4. Analyzing 38. Which statement about a voltage clamp of a neuron at 0 mV is true? a. Once clamped, the membrane depolarizes then returns to resting potential. b. Voltage-gated potassium channels open. c. Apart from the initial current shift from the clamp, no other current is produced. d. Voltage-gated sodium channels close Answer: b Textbook Reference: The Action Potential Bloom’s Category: 4. Analyzing 39. Which statement regarding the structure of the voltage-gated Na+ channels is false? a. P loops mediate ion selectivity. b. It has four domains with extensive sequence homology. c. The channel protein changes its primary structure in response to membrane depolarization. d. A cytoplasmic loop is thought to inactivate the channel by blocking the opening. Answer: c Textbook Reference: The Action Potential Bloom’s Category: 2. Understanding 40. A spiking neuron and a nonspiking neuron share which characteristic? a. High concentration of voltage-gated Na+ channels at the axon hillock b. A graded potential down the entire length of the axon c. An action potential down the entire length of the axon d. Neurotransmitter secretion based on a change in membrane potential Answer: d Textbook Reference: The Action Potential Bloom’s Category: 4. Analyzing 41. How do nonspiking neurons function even though their depolarization signal significantly degrades with distance? a. Voltage-gated Na+ channels are replaced by ligand-gated Na+ channels. b. These neurons are very short, so there is no major signal decrement. © 2016 Sinauer Associates, Inc. c. There are sufficient numbers of voltage-gated Na+ channels to convey the signal without major decrement. d. Voltage-gated K+ channels compensate for the lack of voltage-gated Na+ channels. Answer: b Textbook Reference: The Action Potential Bloom’s Category: 2. Understanding 42.–44. Refer to the figure below. 42. The figure depicts a a. neuronal action potential. b. cardiac action potential. c. pacemaker potential. d. graded potential. Answer: b Textbook Reference: The Action Potential Bloom’s Category: 4. Analyzing 43. What is the best explanation for the plateau shown in the figure? a. Voltage-gated Na+ channels remain open. b. Voltage-gated Ca2+ channels remain open. c. Voltage-gated K+ channels close. d. Leaky K+ channels remain open. Answer: b Textbook Reference: The Action Potential Bloom’s Category: 4. Analyzing 44. Which statement about ion permeability as shown in the figure is true? a. K+ permeability is at its lowest very close to the membrane potential peak. © 2016 Sinauer Associates, Inc. b. K+ permeability is at its highest very close to the membrane potential peak. c. Na+ permeability is at its lowest very close to the membrane potential peak. d. Na+ permeability is at its highest very close to the membrane potential peak. Answer: d Textbook Reference: The Action Potential Bloom’s Category: 4. Analyzing 45. The absolute refractory period of the action potential is best explained by a. inactivated voltage-gated sodium channels. b. closed voltage-gated sodium channels. c. open slow calcium channels. d. inactivated voltage-gated potassium channels. Answer: a Textbook Reference: The Action Potential Bloom’s Category: 2. Understanding 46. Which statement about a local circuit in an axon is false? a. Ions flow in intracellular fluid, carrying current to more distant parts of the membrane. b. At the membrane, the ion movements change the distribution of charges on the membrane capacitance. c. An ionic current completes the local circuit as cations move toward the locus of the action potential and anions move away. d. Anions migrate into the membrane interior. Answer: d Textbook Reference: The Propagation of Action Potentials Bloom’s Category: 4. Analyzing 47. _______ prevents bidirectional propagation of action potentials. a. The inactivation of Na+ channels b. A decrease in membrane resistance c. Myelination d. The K+ channel Answer: a Textbook Reference: The Propagation of Action Potentials Bloom’s Category: 2. Understanding 48. Conduction velocity shows _______ axon diameter. a. a proportional relationship to b. a proportional relationship to the square root of c. an exponential relationship to d. either a proportional relationship to, or a proportional relationship to the square root of Answer: d Textbook Reference: The Propagation of Action Potentials Bloom’s Category: 2. Understanding © 2016 Sinauer Associates, Inc. 49. Considering neurons in living systems, which variable affects conduction velocity the most? a. Myelination b. Temperature c. Length d. Diameter Answer: a Textbook Reference: The Propagation of Action Potentials Bloom’s Category: 5. Evaluating 50. Myelination by Schwann cells increases the velocity of action potential propagation by a. increasing the resistance and decreasing the capacitance, allowing the action potential to “jump” over the myelinated area. b. decreasing the resistance and increasing the capacitance, allowing the action potential to “jump” over the myelinated area. c. increasing the resistance and increasing the capacitance, allowing the action potential to “jump” over the myelinated area. d. increasing the diameter of the neuron. Answer: a Textbook Reference: The Propagation of Action Potentials Bloom’s Category: 2. Understanding Short Answer 1. Compare and contrast nervous systems and endocrine systems. Answer: Neural and endocrine systems are both systems for communication within the body. Nervous systems are faster and capable of much finer temporal and spatial control, whereas endocrine systems typically control more widespread and prolonged activities. Textbook Reference: The Physiology of Control: Neurons and Endocrine Cells Compared Bloom’s Category: 2. Understanding 2. Describe the startle response in the cockroach. Answer: The cockroach’s startle response is a reflex. Sound waves or air vibrate the filiform hair receptors, which generate impulses in sensory neurons. The sensory neurons excite the giant interneurons that synapse with leg motor neurons. Once excited, the leg motor neurons activate the leg muscles. Textbook Reference: Neurons Are Organized into Functional Circuits in Nervous Systems Bloom’s Category: 2. Understanding 3. What are glial cells and how do they aid in the function of the nervous system? Answer: Glial cells are the support cells of the nervous system. They form the myelin around neurons, which increases action potential velocity. They surround capillaries and © 2016 Sinauer Associates, Inc. act as metabolic intermediaries between neurons and their circulatory supply. They also serve immune and scavenging functions in order to protect surrounding neurons. Textbook Reference: The Cellular Organization of Neural Tissue Bloom’s Category: 2. Understanding 4. Compare and contrast current and voltage with respect to the cell membrane. Answer: The net movement of charge constitutes an electric current. The separation of positive and negative charges constitutes a voltage. In terms of the cell membrane, the current would be a flow of ions through channels in the membrane, whereas the voltage would be the separation of charges across the membrane. Textbook Reference: The Ionic Basis of Membrane Potentials Bloom’s Category: 2. Understanding 5. Since the bulk solutions that make up the intracellular and extracellular fluids maintain charge neutrality, how does the cell produce membrane potentials? Answer: The charge separation producing the membrane potential is an extraordinarily local phenomenon. According to Figure 12.11, in any given 1 µm3 section around each side of the membrane, only six pairs of ions, from the 110,000 cations and 110,000 anions in each fluid compartment, need to sit on the membrane to charge its capacitance, producing a membrane potential of –90 mV. Textbook Reference: The Ionic Basis of Membrane Potentials Bloom’s Category: 2. Understanding 6. Explain in mechanistic terms how the action potential is an all-or-none phenomenon. Answer: The action potential is initiated only when a threshold depolarization is reached near the axon hillock. That is, a certain critical number of voltage-gated Na+ channels have to open in order to cause a depolarization that is strong enough to initiate the Hodgkin cycle and, by definition, perpetuate the further opening of voltage-gated Na+ channels via their own depolarization. If the threshold is not reached, there will be no Hodgkin cycle or action potential. Textbook Reference: The Action Potential Bloom’s Category: 2. Understanding 7. Compare and contrast the techniques of patch clamping and voltage clamping. Answer: Both patch clamping and voltage clamping provide experimental information about membrane currents, especially during an action potential. The patch-clamp technique uses a micropipette to record single channel currents, whereas the voltage- clamp technique shows whole cell ionic currents. Textbook Reference: The Action Potential Bloom’s Category: 2. Understanding 8. What are the similarities and differences among the channels in the voltage-gated channel superfamily? Answer: All the voltage-gated channels have principal subunits with extensive sequence homology and thus are evolutionarily related. Voltage-gated Na+ and Ca2+ channels have © 2016 Sinauer Associates, Inc. four domains, whereas the voltage-gated K+ channel has one domain that is homologous to one of the domains on the Na+ channel. Textbook Reference: The Action Potential Bloom’s Category: 2. Understanding 9. Explain in mechanistic terms why the action potential can travel a great distance along an axon without degrading. Answer: The same mechanism that is responsible for the rising phase of the action potential also aids in its perpetuation along the axon without degradation. The action potential on one location on the axon can itself initiate an action potential at a neighboring location, and the induced action potential will have the same all-or-none amplitude as the original. Textbook Reference: The Propagation of Action Potentials Bloom’s Category: 2. Understanding 10. Describe the significance of myelination. Answer: Myelination greatly increases conduction velocity of an axon by increasing the membrane resistance while decreasing the membrane capacitance. In other words, conduction velocity is increased by increasing the length constant without increasing the time constant. Action potentials occur only at the nodes of Ranvier, in a process that is called saltatory conduction. Textbook Reference: The Propagation of Action Potentials Bloom’s Category: 2. Understanding ONLINE QUIZ QUESTIONS 1. The neuron converts an electrical signal to a chemical signal in the a. dendrite. b. presynaptic terminal. c. cell body. d. axon hillock. Answer: b Textbook Reference: The Physiology of Control: Neurons and Endocrine Cells Compared Bloom’s Category: 1. Remembering 2. Neurons that relay sensory signals to integrative centers of the CNS are called a. interneurons. b. afferent neurons. c. synaptic neurons. d. efferent neurons. Answer: b Textbook Reference: The Physiology of Control: Neurons and Endocrine Cells Compared © 2016 Sinauer Associates, Inc. Bloom’s Category: 1. Remembering 3. Which glial cells function as metabolic intermediaries between capillaries and neurons? a. Schwann cells b. Oligodendrocites c. Astrocytes d. Microglial cells Answer: c Textbook Reference: The Cellular Organization of Neural Tissue Bloom’s Category: 1. Remembering 4. Which term best describes the movement of ions across a membrane? a. Current b. Voltage c. Resistance d. Capacitance Answer: a Textbook Reference: The Ionic Basis of Membrane Potentials Bloom’s Category: 1. Remembering 5. A decrease in the absolute value of the membrane potential toward zero is called a. depolarization. b. an action potential. c. hyperpolarization. d. a membrane potential. Answer: a Textbook Reference: The Ionic Basis of Membrane Potentials Bloom’s Category: 1. Remembering 6. Which of the following actively contributes to the cell’s membrane potential? a. Permeability to K+ b. Permeability to Na+ c. The overall resistance of the membrane d. Electrogenic ion pumps Answer: d Textbook Reference: The Ionic Basis of Membrane Potentials Bloom’s Category: 5. Evaluating 7. The time constant (τ) depends on the _______ of the membrane. a. resistance b. capacitance c. resistance and voltage d. resistance and capacitance Answer: d Textbook Reference: The Ionic Basis of Membrane Potentials © 2016 Sinauer Associates, Inc. Bloom’s Category: 2. Understanding 8. If a current pulse is generated on the membrane and creates a passive potential, which statement will be true? a. The change in the membrane potential will increase as the distance from the current pulse increases. b. The change in the membrane potential will decrease as the distance from the current pulse increases. c. The change in the membrane potential will remain constant throughout the length of the membrane. d. The change in the membrane potential will fluctuate depending on the strength of the initial current pulse. Answer: b Textbook Reference: The Ionic Basis of Membrane Potentials Bloom’s Category: 3. Applying 9. The plasma membrane of a resting neuron is most permeable to which ion? a. Na+ b. K+ c. Cl– d. Ca2+ Answer: b Textbook Reference: The Ionic Basis of Membrane Potentials Bloom’s Category: 2. Understanding 10. If ouabain was used to block Na+–K+-ATPase pumps, a. Na+ would go to equilibrium across the cell membrane. b. the membrane potential would become more negative. c. the concentration of K+ would be equal on both sides of the membrane. d. the cell would maintain steady state with a different membrane potential. Answer: a Textbook Reference: The Ionic Basis of Membrane Potentials Bloom’s Category: 3. Applying 11. In a typical neuron, which ion is in passive equilibrium across the cell membrane? a. Na+ b. K+ c. Cl– d. Both Na+ and K+ Answer: c Textbook Reference: The Ionic Basis of Membrane Potentials Bloom’s Category: 2. Understanding 12. A stimulating depolarizing current that depolarizes the axon hillock just slightly negative to the threshold will a. not change the overall membrane potential at all. © 2016 Sinauer Associates, Inc. b. produce an action potential. c. produce a very small action potential. d. produce a temporary graded potential. Answer: d Textbook Reference: The Action Potential Bloom’s Category: 2. Understanding 13. _______ channels govern the generation of an action potential. a. Ligand-gated Na+ b. Ligand-gated K+ c. Voltage-gated Na+ d. Voltage-gated K+ Answer: c Textbook Reference: The Action Potential Bloom’s Category: 1. Remembering 14. Considering the cycle of an action potential, when is the permeability to K+ at its greatest? a. During the resting membrane potential b. During the rising phase of the action potential c. At the peak of the action potential d. During the falling phase of the action potential Answer: d Textbook Reference: The Action Potential Bloom’s Category: 2. Understanding 15. Which statement regarding the action potential is false? a. In an extremely long axon, the action potential eventually will degrade. b. During the “falling” phase, K+ permeability increases. c. During the “rising” phase, Na+ moves into the neuron. d. In the recovery phase, Na+ channels are closed. Answer: a Textbook Reference: The Action Potential Bloom’s Category: 5. Evaluating 16. What allows the action potential to return to a repolarized state? a. Voltage-gated Na+ channels become inactivated. b. Voltage-gated K+ channels become inactivated. c. Na+ reaches equilibrium across the neural membrane and stops leaking in. d. Voltage-gated Na+ channels close. Answer: a Textbook Reference: The Action Potential Bloom’s Category: 2. Understanding 17. Which statement regarding cardiac pacemaker cells is false? a. They spontaneously generate action potentials. © 2016 Sinauer Associates, Inc. b. The frequency of action potential generation can be modified by neural input. c. The pacemaker cells are modified neural tissue. d. They are connected to myocardium via gap junctions. Answer: c Textbook Reference: The Action Potential Bloom’s Category: 5. Evaluating 18. _______ are responsible for extending the time of the cardiac action potential relative to a neural action potential. a. Slow Ca2+ channels b. Slow Na+ channels c. Slow K+ channels d. Voltage-gated Na+ channels Answer: a Textbook Reference: The Action Potential Bloom’s Category: 2. Understanding 19. Which character of neurons affects conduction velocity the least? a. Axon diameter b. Myelination c. Axon length d. Temperature Answer: c Textbook Reference: The Propagation of Action Potentials Bloom’s Category: 5. Evaluating 20. In myelinated axons, action potentials occur a. all along the axon. b. only at the internodes. c. only at the initial segment of the axon. d. only at the nodes of Ranvier. Answer: d Textbook Reference: The Propagation of Action Potentials Bloom’s Category: 2. Understanding © 2016 Sinauer Associates, Inc.