BIO, Chapter 48 Nervous Systems Testank
Chapter Questions
1) Which of the following is (are) characteristic of a simple nervous system?
A) a nerve net such as is found in cnidarians
B) nerve cell ganglia
C) having electrical impulses traveling in both directions
D) both A and C
E) A, B, and C Answer: D
Topic: Concept 48.1
Skill: Knowledge
2) Which of the following is associated with the evolution of a central nervous system?
A) a complete gut
B) bilateral symmetry
C) radial symmetry
D) a closed circulatory system
E) excitable membranes Answer: B
Topic: Concept 48.1
Skill: Knowledge
3) An organism that lacks integration centers A) cannot receive stimuli.
B) will not have a nervous system.
C) will not be able to interpret stimuli.
D) can be expected to lack myelinated neurons.
E) both A and D Answer: C
Topic: Concept 48.1
Skill: Comprehension 4) Where is the most likely location of a group of nerve cell bodies known as a ganglion?
A) in the central nervous system
B) in the peripheral nervous system
C) anywhere in the nervous system
D) within the brain
E) within the spinal cord Answer: B
Topic: Concept 48.1
Skill: Knowledge
5) The general functions of the nervous system include which of the following?
I. integration
II. motor output
III. sensory input
A) I only
B) II only
C) III only
D) I and II only
E) I, II, and III
Answer: E
Topic: Concept 48.1
Skill: Comprehension 6) What do muscles, nerves, and glands have in common? A) They synapse with neurons.
B) They are referred to as postsynaptic cells.
C) They are target cells.
D) A and B only
E) A, B, and C
Answer: E
Topic: Concept 48.1
Skill: Comprehension
7) Integration of simple responses to certain stimuli, such as the patellar reflex, is accomplished by which of the following? A) spinal cord
B) hypothalamus
C) corpus callosum
D) cerebellum
E) medulla
Answer: A
Topic: Concept 48.1
Skill: Knowledge
8) The blood-brain barrier
A) is formed by tight junctions.
B) is formed by oligodendrocytes.
C) tightly regulates the intracellular environment of the CNS.
D) uses chemical signals to communicate with the spinal cord.
E) provides support to the brain tissue.
Answer: A
Topic: Concept 48.1
Skill: Comprehension 9) Which of the following statements is false? A) All cells have a membrane potential.
B) Gray matter is the site of neuronal integration.
C) Astrocytes can communicate with nerve cells.
D) The outside of a cell is negative with respect to the inside of a cell.
E) Squid axons are a model system for nerve conductance.
Answer: D
Topic: Concept 48.2
Skill: Comprehension
10) If the concentration of potassium in the cytoplasm of a nerve cell with a resting membrane potential of -70 mV were elevated above normal, the new resting potential would A) still be -70 mV.
B) be -69 mV or higher.
C) be -71 mV or lower.
D) be 0 mV.
E) reverse polarity.
Answer: B
Topic: Concept 48.2
Skill: Application
11) Neurons at rest are not at the equilibrium potential for K+ because the cell membrane is A) only permeable to K+.
B) slightly permeable to Na+.
C) not permeable to Na+.
D) not permeable to K+.
E) only permeable to Na+.
Answer: B
Topic: Concept 48.2
Skill: Knowledge 12) If an otherwise normal nerve cell were made permeable to large negative ions, what would happen? A) The membrane potential would not form.
B) Potassium would not leave the resting cell.
C) Sodium would not enter the resting cell.
D) The membrane potential would become positive.
E) The sodium-potassium pump would not function.
Answer: A
Topic: Concept 48.2
Skill: Comprehension
13) The sodium-potassium pump of neurons pumps A) Na+ and K+ into the cell.
B) Na+ and K+ out of the cell.
C) Na+ into the cell and K+ out of the cell.
D) Na+ out of the cell and K+ into the cell.
E) Na+ and K+ into the cell and H+ out of the cell through an antiport.
Answer: D
Topic: Concept 48.2
Skill: Knowledge
The questions below refer to the following information:
A previously unknown organism has been discovered. It contains long cells with excitable membranes that scientists suspect are used for rapid information transfer. The membrane of the cell is permeable only to ion X, which carries a negative charge. Active transport pumps in the membrane move X into the cell while simultaneously moving ion Y, also carrying a negative charge, out of the cell. 14) Which of the following is true about the establishment of the resting membrane potential in this cell? A) The resting potential of this cell will be zero.
B) The resting potential of this cell will be negative.
C) A negative resting potential is directly produced by the pump moving a negative charge into the cell.
D) A negative resting potential is directly produced by the diffusion of Y– into the cell.
E) A positive resting potential is directly produced by the diffusion of X– out of the cell.
Answer: E
Topic: Concept 48.2
Skill: Application
15) When neurotransmitter Z is released into the extracellular fluid in contact with a portion of the cell membrane, channels open that allow both X– and Y– through the membrane. Which of the following is incorrect?
A) The magnitude of the potential will immediately increase.
B) Y– will diffuse into the cell.
C) X– will diffuse out of the cell.
D) The membrane will depolarize.
E) The channels are chemically gated.
Answer: A
Topic: Concept 48.2 Skill: Application 16) Which of the following is a correct statement about a resting neuron? A) It releases lots of acetylcholine.
B) The membrane is very leaky to sodium.
C) The membrane is equally permeable to sodium and potassium.
D) The membrane potential is more negative than the threshold potential.
E) The concentration of sodium is greater inside the cell than outside.
Answer: D
Topic: Concept 48.2 Skill: Knowledge 17) Which of following is a true statement about the threshold potential of a membrane? A) It is equal to about 35 mV.
B) It is equal to about 70 mV.
C) It opens voltage-sensitive gates that result in the rapid outflow of sodium ions.
D) It is the depolarization that is needed to generate an action potential.
E) It is a graded potential that is proportional to the strength of a stimulus.
Answer: D
Topic: Concept 48.3
Skill: Knowledge
18) Which statement about transmission along neurons is false?
A) The rate of transmission of a nerve impulse is directly related to the diameter of the axon.
B) The intensity of a stimulus is related to the magnitude of the action potential.
C) The resting potential is maintained by differential ion permeabilities and the sodium-potassium pump.
D) Once initiated, local depolarizations stimulate a propagation of serial action potentials down the axon. E) A stimulus that affects the membrane's permeability to ions can either depolarize or hyperpolarize the membrane.
Answer: B
Topic: Concept 48.3
Skill: Comprehension
19) What is the mode of action of a toxin that binds specifically to the voltage-gated sodium channels of axons?
A) block all sodium movement
B) block repolarization
C) prevent the axon from reaching the threshold potential
D) A and B only
E) A, B, and C Answer: C
Topic: Concept 48.3
Skill: Application
20) After an action potential, the resting potential is restored by A) the opening of sodium activation gates.
B) the opening of voltage-sensitive potassium channels and the closing of sodium activation gates.
C) an increase in the membrane's permeability to potassium and chloride ions.
D) the delay in the action of the sodium-potassium pump.
E) the refractory period in which the membrane is hyperpolarized.
Answer: B
Topic: Concept 48.3
Skill: Knowledge
21) Repolarization of the membrane of a neuron after an action potential is a consequence of which of the following?
I. calcium channels opening
II. Na+ channels inactivating III. K+ channels opening
A) I only
B) II only
C) III only
D) I and II only
E) II and III only Answer: E
Topic: Concept 48.3
Skill: Comprehension
22) In the sequence of permeability changes that depolarizes and then repolarizes the membrane of a neuron during an action potential, which of the following changes occurs first? A) Sodium gates open.
B) The sodium-potassium pump shuts down.
C) The sodium-potassium pump is activated.
D) Potassium gates close.
E) Potassium gates open.
Answer: A
Topic: Concept 48.3
Skill: Knowledge
For the following questions, refer to the graph of an action potential in Figure 48.1 and use the letters to indicate your answer.
Figure 48.1
23) The membrane is unable to respond to any further stimulation, regardless of intensity.
Answer: D
Topic: Concept 48.3
Skill: Comprehension 24) The sodium gates open.
Answer: A
Topic: Concept 48.3
Skill: Comprehension 25) The threshold potential is reached.
Answer: A
Topic: Concept 48.3
Skill: Comprehension 26) Repolarization occurs, sodium gates close, and some potassium gates reopen.
Answer: C
Topic: Concept 48.3
Skill: Comprehension
27) The membrane is at resting potential.
Answer: E
Topic: Concept 48.3
Skill: Comprehension
28) Action potentials are normally carried in one direction from the axon hillock to the axon terminals. By using an electronic probe, you experimentally depolarize the middle of the axon to threshold. What do you expect?
A) No action potential will be initiated.
B) An action potential will be initiated and proceed in the normal direction toward the axon terminal.
C) An action potential will be initiated and proceed back toward the axon hillock.
D) Two action potentials will be initiated, one going toward the axon terminal and one going back toward the hillock.
E) An action potential will be initiated, but it will die out before it reaches the axon terminal.
Answer: D
Topic: Concept 48.3
Skill: Application
29) Saltatory conduction is a term applied to conduction of impulses A) across electrical synapses.
B) along the postsynaptic membrane from dendrite to axon hillock.
C) in two directions at the same time.
D) from one neuron to another.
E) along myelinated nerve fibers.
Answer: E
Topic: Concept 48.3
Skill: Knowledge 30) Which animal movement could be used to represent impulse conductance along a myelinated axon?
A) a person out on a power walk
B) an earthworm moving along the surface of the ground
C) an amoeba extending pseudopodia
D) a moth moving toward a light
E) a frog leaping between lily pads
Answer: E
Topic: Concept 48.3 Skill: Application 31) Where do synaptic vesicles discharge their contents by exocytosis?
A) dendrite
B) axon hillock
C) nodes of Ranvier
D) postsynaptic membrane
E) presynaptic membrane
Answer: E
Topic: Concept 48.4
Skill: Knowledge
32) Neurotransmitters are released from presynaptic axon terminals into the synaptic cleft by which mechanism?
A) osmosis
B) active transport
C) diffusion
D) endocytosis E) exocytosis Answer: E
Topic: Concept 48.4
Skill: Knowledge
33) Which of the following offers the best description of neural transmission across a mammalian synaptic gap? A) Neural impulses involve the flow of K+ and Na+ across the gap.
B) Neural impulses travel across the gap as electrical currents.
C) Neural impulses cause the release of chemicals that diffuse across the gap.
D) Neural impulses travel across the gap in both directions.
E) The calcium within the axons and dendrites of nerves adjacent to a synapse acts as the neurotransmitter. Answer: C
Topic: Concept 48.4
Skill: Knowledge
34) One disadvantage to a nerve net is that it can conduct impulses in two directions from the point of the stimulus. The vertebrate system conducts in only one direction. This one-way conduction occurs A) as a result of the nodes of Ranvier.
B) as a result of voltage-gated sodium channels found in the vertebrate system.
C) because vertebrate nerve cells have dendrites.
D) because only the postsynaptic cells can bind neurotransmitters.
E) because the sodium-potassium pump moves ions in one direction.
Answer: D
Topic: Concept 48.4
Skill: Comprehension
35) During an IPSP, the membrane of the postsynaptic cell becomes more permeable to A) K+.
B) Na+.
C) Ca2+.
D) GABA.
E) serotonin.
Answer: A
Topic: Concept 48.4
Skill: Knowledge
36) Given the steps shown below, which of the following is the correct sequence for transmission at a chemical synapse?
1. Neurotransmitter binds with receptors associated with the postsynaptic membrane.
2. Ca2+ ions rush into neuron's cytoplasm.
3. Action potential depolarizes the synaptic terminal membrane.
4. Ligand-gated ion channels open.
5. Synaptic vesicles release neurotransmitter into the synaptic cleft.
A) 1, 2, 3, 4, 5
B) 2, 3, 5, 4, 1
C) 3, 2, 5, 1, 4
D) 4, 3, 1, 2, 5
E) 5, 1, 2, 4, 3 Answer: C
Topic: Concept 48.4
Skill: Comprehension
37) A drug might act as a stimulant of the somatic nervous system if it A) makes the membrane permanently impermeable to sodium.
B) stimulates the activity of acetylcholinesterase in the synaptic cleft.
C) increases the release of substances that cause the hyperpolarization of the neurons.
D) increases the sensitivity of the postsynaptic membrane to acetylcholine.
E) increases the sensitivity of the presynaptic membrane to acetylcholine.
Answer: D
Topic: Concept 48.4
Skill: Comprehension
38) How does an EPSP facilitate depolarization of the postsynaptic membrane?
A) by increasing the permeability of the membrane to Na+
B) by increasing the permeability of the membrane to K+
C) by insulating the hillock region of the axon
D) by allowing Cl– to enter the cell
E) by stimulating the sodium-potassium pump
Answer: A
Topic: Concept 48.4
Skill: Knowledge
39) The postsynaptic membrane of a nerve may be stimulated by certain neurotransmitters to permit the influx of negative chloride ions into the cell. This process will result in A) membrane depolarization.
B) an action potential.
C) the production of an IPSP.
D) the production of an EPSP.
E) the membrane becoming more positive.
Answer: C
Topic: Concept 48.5
Skill: Comprehension
40) Neurotransmitters categorized as inhibitory would not be expected to A) bind to receptors.
B) open K+ channels.
C) open Na+ channels.
D) open Cl– channels.
E) hyperpolarize the membrane.
Answer: C
Topic: Concept 48.4
Skill: Comprehension
41) Which of the following statements is true regarding temporal summation?
A) The sum of simultaneously arriving neurotransmitters from different presynaptic nerve cells determines whether the postsynaptic cell fires.
B) Several action potentials arrive in fast succession without allowing the postsynaptic cell to return to its resting potential.
C) Several IPSPs arrive concurrently, bringing the presynaptic cell closer to its threshold.
D) Several postsynaptic cells fire at the same time when neurotransmitters are released from several synaptic terminals simultaneously.
E) The voltage spike of the action potential that is initiated is higher than normal.
Answer: B
Topic: Concept 48.4
Skill: Knowledge
42) A single inhibitory postsynaptic potential has a magnitude of 0.5 mV at the axon hillock, and a single excitatory postsynaptic potential has a magnitude of 0.5 mV. What will be the membrane potential at the hillock after the spatial summation of 6 IPSPs and 2 EPSPs, if the initial membrane potential is -70 mV? A) -72 mV
B) -71 mV
C) -70 mV
D) -69 mV
E) -68 mV Answer: A
Topic: Concept 48.4
Skill: Application 43) A neurotransmitter can trigger different responses in postsynaptic cells due to which of the following? A) receptor mode of action
B) receptors present
C) concentration of neurotransmitter
D) A and B only
E) A, B, and C Answer: D
Topic: Concept 48.4
Skill: Comprehension
The next questions refer to the following terms. Each term may be used once, more than once, or not at all.
A. meninges
B. ganglion
C. axon hillocks
D. myelin sheaths
E. postsynaptic membranes
44) possess neurotransmitter receptors
Answer: E
Topic: Concept 48.4
Skill: Knowledge
45) usually the sites of the initial action potential in neurons
Answer: C
Topic: Concept 48.4
Skill: Knowledge
46) produced by oligodendrocytes and Schwann cells
Answer: D
Topic: Concept 48.4
Skill: Knowledge 47) Which statement could be applied to both the nervous system and the endocrine system? A) They both use chemical signaling.
B) The final response depends on the receptor mode of action.
C) Specific parts of both systems use chemical messengers produced by axons.
D) Only A and B are correct.
E) A, B, and C are correct.
Answer: E
Topic: Concept 48.4
Skill: Comprehension
48) Neurotransmitters affect postsynaptic cells by A) initiating signal transduction pathways in the cells.
B) causing molecular changes in the cells.
C) affecting ion-channel proteins.
D) altering the permeability of the cells.
E) all of the above Answer: E
Topic: Concept 48.4 Skill: Knowledge
49) What is the main neurotransmitter of the parasympathetic system?
A) acetylcholine
B) cholinesterase
C) norepinephrine
D) adrenaline E) dopamine Answer: A
Topic: Concept 48.4
Skill: Knowledge
50) What is the major inhibitory neurotransmitter of the brain?
A) acetylcholine
B) cholinesterase
C) norepinephrine
D) dopamine
E) GABA Answer: E
Topic: Concept 48.4
Skill: Knowledge
The questions below refer to the following choices of neurotransmitters. Each choice may be used once, more than once, or not at all.
A. acetylcholine
B. epinephrine
C. endorphin
D. serotonin
E. GABA
51) a neuropeptide that functions as a natural analgesic
Answer: C
Topic: Concept 48.4
Skill: Knowledge
52) an amino acid that operates at inhibitory synapses in the brain
Answer: E
Topic: Concept 48.4 Skill: Knowledge 53) Which statement is true?
A) Nitric oxide is an example of a neurotransmitter stored in presynaptic vesicles.
B) Learning does not appear to require a specific number of neurons.
C) Organisms with bilateral symmetry were first to have nerve nets.
D) Biogenic amines are derived from proteins.
E) Serotonin is a neurotransmitter synthesized from tyrosine.
Answer: B
Topic: Concept 48.4
Skill: Comprehension
54) Cerebrospinal fluid can be described as all of the following except A) functioning in transport of nutrients and hormones through the brain.
B) a product of the filtration of blood by the brain.
C) formed from layers of connective tissue.
D) functioning to cushion the brain.
E) filling cavities in the brain called ventricles.
Answer: C
Topic: Concept 48.4
Skill: Knowledge
55) The divisions of the nervous system that have antagonistic actions, or opposing actions are A) motor and sensory.
B) sympathetic and parasympathetic.
C) presynaptic and postsynaptic.
D) forebrain and hindbrain.
E) central nervous system and peripheral nervous system.
Answer: B
Topic: Concept 48.5
Skill: Comprehension
56) Which part of the vertebrate nervous system is most involved in preparation for the fight-or-flight response? A) sympathetic
B) somatic
C) central
D) visceral
E) parasympathetic Answer: A
Topic: Concept 48.5
Skill: Knowledge
57) Which of the following activities would be associated with the parasympathetic division of the nervous system?
A) rest and digestion
B) release of both acetylcholine and epinephrine
C) increased metabolic rate
D) fight-or-flight response
E) release of epinephrine only
Answer: A
Topic: Concept 48.5
Skill: Knowledge 58) Which of the following is correct about the telencephalon region of the brain?A) It develops as the neural tube differentiates.
B) It develops from the midbrain.
C) It is the brain region most like that of ancestral vertebrates.
D) It gives rise to the cerebrum.
E) It divides further into the metencephalon and myelencephalon.
Answer: D
Topic: Concept 48.5
Skill: Comprehension 59) What controls the heart rate?
A) neocortex
B) medulla
C) thalamus
D) pituitary
E) cerebellum Answer: B
Topic: Concept 48.5
Skill: Knowledge
60) Which area of the brain is most intimately associated with the unconscious control of respiration and circulation? A) thalamus
B) cerebellum
C) medulla
D) corpus callosum
E) cerebrum Answer: C
Topic: Concept 48.5 Skill: Knowledge 61) Which selection is incorrectly paired?
A) forebrain-diencephalon
B) forebrain-cerebrum
C) midbrain-brainstem
D) midbrain-cerebellum
E) brainstem-pons Answer: D
Topic: Concept 48.5 Skill: Knowledge 62) What would be most affected if an accident caused trauma to the hypothalamus?
A) sorting of sensory information
B) processing of motor information in the cerebellum
C) the production of CSF
D) regulation of body temperature
E) cognitive response ability
Answer: D
Topic: Concept 48.5
Skill: Comprehension
For the next questions, choose the best answer from the following list. Each answer may be used once, more than once, or not at all.
A. cerebrum
B. cerebellum
C. thalamus
D. hypothalamus
E. medulla oblongata
63) produces hormones that are secreted by the pituitary gland
Answer: D
Topic: Concept 48.5
Skill: Knowledge
64) coordinates muscle actions
Answer: B
Topic: Concept 48.6
Skill: Knowledge
65) regulates body temperature
Answer: D
Topic: Concept 48.5
Skill: Knowledge
66) contains regulatory centers for the respiratory and circulatory systems
Answer: E
Topic: Concept 48.5
Skill: Knowledge
67) contains regions that help regulate hunger and thirst
Answer: D
Topic: Concept 48.5 Skill: Knowledge
68) Which processes in animals are regulated by circadian rhythms?
A) sleep cycles
B) hormone release
C) sex drive
D) A and B only
E) A, B, and C Answer: E
Topic: Concept 48.5
Skill: Knowledge
69) By comparing the size and degree of convolution of various vertebrate cerebral cortices, biologists would gain insight into the relative
A) size of the brain centers of taxonomic groups.
B) emotions and learning capabilities of vertebrate classes.
C) motor impulse complexities.
D) sophistication of behaviors.
E) sensory stimuli that regulate motor impulses.
Answer: D
Topic: Concept 48.5
Skill: Comprehension
70) Which of the following statements about the nervous system is incorrect?
A) The three evolutionary changes in the vertebrate brain include increases in relative size, increases in compartmentalization of function, and decreases in cephalization.
B) The size of the primary motor and sensory areas of the cortex devoted to controlling each part of the body is proportional to the importance of that part of the body.
C) Human emotions are believed to originate from interactions between the cerebral cortex and the limbic system.
D) The localization of pain involves the somatosensory cortex.
E) The autonomic nervous system is subdivided into the parasympathetic and sympathetic nervous systems. Answer: A
Topic: Concept 48.6
Skill: Comprehension 71) The motor cortex is part of which part of the nervous system?
A) cerebrum
B) cerebellum
C) spinal cord
D) midbrain E) medulla
Answer: A
Topic: Concept 48.6
Skill: Knowledge
72) What do Wernicke's and Broca's regions of the brain affect?
A) olfaction
B) vision
C) speech
D) memory
E) hearing Answer: C
Topic: Concept 48.6
Skill: Comprehension 73) If you were writing an essay, which part of the brain would be most active?
A) temporal and frontal lobes
B) parietal lobe
C) Broca's area
D) Wernicke's area
E) occipital lobe Answer: A
Topic: Concept 48.6
Skill: Comprehension
74) The establishment and expression of emotions involves the A) frontal lobes and limbic system.
B) frontal lobes and parietal lobes.
C) parietal lobes and limbic system.
D) frontal and occipital lobes.
E) occipital lobes and limbic system.
Answer: A
Topic: Concept 48.6
Skill: Comprehension
75) Our understanding of mental illness has been most advanced by discoveries involving A) degree of convolutions in the brain's surface.
B) evolution of the telencephalon.
C) sequence of developmental specialization.
D) chemicals involved in brain communications.
E) nature of the blood-brain barrier.
Answer: D
Topic: Concept 48.7
Skill: Comprehension
The following questions refer to Figure 48.2.
Figure 48.2
76) Axons are pushed away from the spinal cord by being repelled by Netrin-1 and Slit from the floor plate.
Answer: D
Topic: Concept 48.7
Skill: Comprehension 77) Axons are pulled toward the midline by binding to molecules on the floor plate.
Answer: B
Topic: Concept 48.7
Skill: Comprehension 78) Axons are pulled toward the floor plate by the presence of Netrin-1 molecules.
Answer: A
Topic: Concept 48.7
Skill: Comprehension
Media Activity Questions
79) An impulse relayed along a myelinated axon "jumps" from ________ to ________.
A) oligodendrocyte; Schwann cell
B) node of Ranvier; Schwann cell
C) node of Ranvier; node of Ranvier
D) Schwann cell; Schwann cell
E) Schwann cell; node of Ranvier Answer: C
Topic: Web/CD Activity: Neuron Structure 80) What type of cell makes up the myelin sheath of a motor neuron?
A) astrocytes
B) microglial cells
C) Ranvier cells
D) ependymal cells
E) Schwann cells
Answer: E
Topic: Web/CD Activity: Neuron Structure
81) What part of a neuron relays signals from one neuron to another neuron or to an effector? A) dendrite
B) axon hillock
C) synaptic terminal
D) axon
E) node of Ranvier
Answer: C
Topic: Web/CD Activity: Neuron Structure
82) A stimulus has opened the voltage-gated sodium channels in an area of a neuron's plasma membrane. As a result, ________ rushes into the neuron and diffuses to adjacent areas; this in turn results in the ________ in the adjacent areas.
A) potassium; opening of voltage-gated potassium channels
B) sodium; opening of voltage-gated potassium channels
C) sodium; opening of voltage-gated sodium channels
D) sodium; closing of voltage-gated sodium channels
E) potassium; opening of voltage-gated sodium channels Answer: C
Topic: Web/CD Activity: Nerve Signals: Action Potentials
83) Which of these causes the release of neurotransmitter molecules?
A) the receipt of a signal from the postsynaptic neuron
B) the opening of voltage-gate calcium channels and the diffusion of calcium ions out of the neuron
C) an action potential reaching the end of the cell body
D) an action potential reaching the end of the axon
E) an action potential reaching the end of the dendrite
Answer: D
Topic: Web/CD Activity: Signal Transmission at a Chemical Synapse
Self-Quiz Questions
84) What happens when a neuron's membrane depolarizes? A) There is a net diffusion of Na+ out of the cell.
B) The equilibrium potential for K+ (EK) becomes more positive.
C) The magnitude of the neuron’s membrane voltage is reduced.
D) The neuron becomes less likely to generate an action potential.
E) The inside of the cell becomes more negative relative to the outside. Answer: C 85) Why are action potentials usually conducted in only one direction along an axon? A) The nodes of Ranvier can conduct potentials in only one direction.
B) The brief refractory period prevents reopening of voltage-gated Na+ channels.
C) The axon hillock has a higher membrane potential than the terminals of the axon.
D) Ions can flow along the axon in only one direction.
E) Voltage-gated channels for both Na+ and K+ open in only one direction. Answer: B
86) A common feature of action potentials is that they A) cause the membrane to hyperpolarize and then depolarize.
B) can undergo temporal and spatial summation.
C) are triggered by a depolarization that reaches the threshold.
D) move at the same speed along all axons.
E) result from the diffusion of Na+ and K+ through ligand-gated channels. Answer: C
87) Which of the following is a direct result of depolarizing the presynaptic membrane of an axon terminal?