Chapter 12
99) Rapid impulse conduction from "node" to "node" is called A) spatial propagation. B) saltatory propagation. C) divergent propagation. D) synaptic transmission. E) continuous propagation.
B
104) In which of the following would the rate of impulse conduction be the greatest? A) a myelinated fiber of 10-µm diameter B) a nonmyelinated fiber of 20-µm diameter C) a myelinated fiber of 1-µm diameter D) a nonmyelinated fiber of 10-µm diameter E) It would be the same in all because of the all-or-none principle.
A
101) Which of the following types of nerve fiber possesses the fastest speed of impulse propagation? A) type A B) type B C) type C D) type D E) type E
A
103) Sensory information from skeletal muscles travels over ________ fibers. A) type A B) type B C) type C D) type D E) type E
A
106) Which type of synapse is most common in the nervous system? A) chemical B) electrical C) mechanical D) processing E) radiative
A
110) If the chemically gated sodium channels in the postsynaptic membrane were completely blocked, A) synaptic transmission would fail. B) release of neurotransmitter would stop. C) smaller action potentials would result. D) the presynaptic membrane would be unable to reach threshold. E) the presynaptic neuron would release a different neurotransmitter.
A
112) When cholinergic receptors are stimulated, A) sodium ions enter the postsynaptic neuron. B) sodium ions leave the postsynaptic neuron. C) chloride ions enter the postsynaptic neuron. D) chloride ions leave the postsynaptic neuron. E) norepinephrine deactivates acetylcholine.
A
117) Which of the following is the most important excitatory neurotransmitter in the brain that is important in learning and memory? A) glutamate B) gamma aminobutyric acid C) serotonin D) noradrenaline E) glycine
A
13) Axons terminate in a series of fine extensions known as A) telodendria. B) terminals. C) collaterals. D) dendrites. E) synapses.
A
17) Neurons that are rare, small, and lack features that distinguish dendrites from axons are called A) anaxonic. B) unipolar. C) bipolar. D) tripolar. E) multipolar.
A
21) Sensory neurons of the PNS are A) unipolar. B) bipolar. C) anaxonic. D) multipolar. E) tripolar.
A
22) Which of the following activities or sensations is/are not monitored by interoceptors? A) sight B) taste C) activities of the digestive system D) cardiovascular activities E) urinary activities
A
26) ________ neurons are the most common structural class in the CNS. A) Multipolar B) Anaxonic C) Unipolar D) Bipolar E) Sensory
A
42) The largest and most numerous of the glial cells in the central nervous system are the A) astrocytes. B) satellite cells. C) oligodendrocytes. D) microglia. E) ependymal cells.
A
46) The neuroglial cells that participate in maintaining the blood-brain barrier are the A) astrocytes. B) ependymal cells. C) microglia. D) oligodendrocytes. E) Schwann cells.
A
61) Opening of sodium channels in the axon membrane causes A) depolarization. B) repolarization. C) hyperpolarization. D) increased negative charge inside the membrane. E) inhibition.
A
64) Integral membrane proteins that connect electrical synapses are called A) connexons. B) receptors. C) desmosomes. D) sodium channels. E) synapsins.
A
65) The equilibrium potential for potassium ion occurs at approximately A) -90 mV. B) -70 mV. C) +66 mV. D) 0 mV. E) +30 mV.
A
71) If the sodium-potassium pumps in the plasma membrane fail to function, all of the following occur except A) the intracellular concentration of potassium ions will increase. B) the neuron will slowly depolarize. C) the membrane will slowly lose its capacity to generate action potentials. D) the inside of the membrane will have a resting potential that is more positive than normal. E) the intracellular concentration of sodium ions will increase.
A
76) Voltage-gated sodium channels have both an activation gate and a(n) ________ gate. A) inactivation B) ion C) swinging D) repolarization E) threshold
A
82) The same ________ can have different effects depending on the properties of the ________. A) neurotransmitter; receptor B) receptor; neurotransmitter C) substrate; receptor D) hormone; neurotransmitter E) propagation; neurotransmitter
A
83) Which of the following statements about the action potential is false? A) The rapid depolarization phase is caused by the entry of potassium ions. B) During the repolarization phase, sodium channels close and potassium channels open. C) During the depolarization phase, membrane potential becomes positive. D) During the hyperpolarization phase, the ion pumps re-establish the sodium and potassium concentrations across the cell membrane. E) Repolarization occurs as potassium ions leave the axon.
A
84) How would the absolute refractory period be affected if voltage-regulated sodium channels failed to inactivate? A) It would last indefinitely. B) It would be much briefer. C) It would be basically unaffected.
A
87) A threshold stimulus is the A) depolarization necessary to cause an action potential. B) peak of an action potential. C) hyperpolarization of an axon. D) resting potential. E) electrical current that crosses the synaptic cleft.
A
88) Which of the following is true about threshold for an action potential? A) It is more positive than the resting potential. B) Voltage-gated potassium channels begin to close. C) Voltage-gated potassium channels begin to open. D) The membrane begins to hyperpolarize. E) Threshold for a typical neuron is approximately -30 mV.
A
109) The following are the steps involved in transmission at a cholinergic synapse. What is the correct sequence for these events? 1. Chemically-gated sodium channels on the postsynaptic membrane are activated. 2. Calcium ions enter the synaptic terminal. 3. Acetylcholinesterase hydrolyzes acetylcholine. 4. An action potential depolarizes the synaptic terminal at the presynaptic membrane. 5. The pre-synaptic terminal reabsorbs choline. 6. Acetylcholine is released from storage vesicles by exocytosis. 7. Acetylcholine binds to receptors on the postsynaptic membrane. 8. Calcium ions are removed from the cytoplasm of the pre- synaptic terminal. A) 4, 2, 6, 7, 8, 5, 3, 1 B) 4, 2, 6, 7, 1, 8, 3, 5 C) 2, 4, 6, 7, 1, 8, 3, 5 D) 2, 5, 4, 6, 7, 1, 8, 3 E) 6, 4, 2, 7, 1, 8, 3, 5
B
113) If the axon terminal of a motor neuron suddenly became permeable to calcium ion, A) the neuron will fire an action potential. B) the motor end plate will be depolarized. C) the motor end plate will be hyperpolarized. D) neurotransmitter release will be blocked. E) the neuron will become unable to stimulate the muscle cell.
B
116) Adrenergic synapses release the neurotransmitter A) acetylcholine. B) norepinephrine. C) dopamine. D) serotonin. E) GABA.
B
16) The rabies virus travels to the CNS via A) anterograde axoplasmic transport. B) retrograde axoplasmic transport. C) blood vessels. D) subcutaneous connective tissue. E) cerebrospinal fluid.
B
18) Neurons in which dendritic and axonal processes are continuous and the soma lies off to one side are called A) anaxonic. B) unipolar. C) bipolar. D) tripolar. E) multipolar.
B
23) ________ neurons are small and have no anatomical features that distinguish dendrites from axons. A) Multipolar B) Anaxonic C) Unipolar D) Bipolar E) Sensory
B
27) ________ neurons form the afferent division of the PNS. A) Visceral sensory B) Sensory C) Neural sensory D) Somatic sensory E) Motor
B
29) Most CNS neurons lack centrioles. This observation explains A) why CNS neurons grow such long axons. B) why CNS neurons cannot divide to regenerate damaged tissue. C) the ability of neurons to generate an action potential. D) the ability of neurons to communicate with each other. E) the ability of neurons to produce a resting potential.
B
4) The part of the peripheral nervous system that carries sensory information to the CNS is designated A) motor. B) afferent. C) efferent. D) autonomic. E) somatic.
B
40) Which of the following is not a function of the neuroglia? A) support B) memory C) secretion of cerebrospinal fluid D) maintenance of blood-brain barrier E) phagocytosis
B
41) Which of the following is a type of glial cell found in the peripheral nervous system? A) astrocytes B) satellite cells C) oligodendrocytes D) microglia E) ependymal cells
B
43) Functions of astrocytes include all of the following except A) maintaining the blood-brain barrier. B) conducting action potentials. C) guiding neuron development. D) responding to neural tissue damage. E) forming a three-dimensional framework for the CNS.
B
51) Glial cells that surround the neurons in ganglia are A) astrocytes. B) satellite cells. C) oligodendrocytes. D) microglia. E) ependymal cells.
B
52) Many medications introduced into the bloodstream cannot directly affect the neurons of the CNS because A) oligodendrocytes form a continuous myelin sheath around the axons. B) the endothelium of CNS capillaries forms a blood-brain barrier. C) the neurolemma is impermeable to most molecules. D) ependymal cells restrict the flow of interstitial fluid between the capillaries and the neurons. E) astrocytes form a capsule around neurons.
B
54) Damage to ependymal cells would most likely affect the A) formation of myelin sheaths. B) formation of cerebrospinal fluid. C) formation of ganglia. D) repair of axons. E) transport of neurotransmitters within axons.
B
58) Which of the following is not true regarding the establishment of a neuron's resting potential? A) Chemical and electrical forces both favor sodium ions entering the cell. B) Electrical forces push sodium ions into the cell. C) The chemical gradient for potassium ions tends to drive them out of the cell. D) Ion pumps in the plasma membrane eject sodium ions as fast as they cross the membrane. E) Resting membrane permeability to Na+ is very low.
B
73) When potassium channels open and the ions diffuse through the membrane, A) the inside of the membrane will become more positive. B) the inside of the membrane will become more negative. C) there will be almost no effect on transmembrane potential. D) the membrane will become depolarized. E) the membrane will depolarize to threshold.
B
79) If the axolemma becomes more permeable to potassium ion, A) the membrane will depolarize to threshold. B) a stronger stimulus will be required to cause an action potential. C) the membrane will depolarize to +30 mV. D) sodium ions will enter the cell to replace the lost potassium ions. E) the inside of the membrane will have a positive charge.
B
80) The following are the main steps in the generation of an action potential. 1. Sodium channels are inactivated. 2. Voltage-gated potassium channels open and potassium moves out of the cell, initiating repolarization. 3. Sodium channels regain their normal properties. 4. A graded depolarization brings an area of an excitable membrane to threshold. 5. A temporary hyperpolarization occurs. 6. Sodium channel activation occurs. 7. Sodium ions enter the cell and depolarization occurs. What is the proper sequence of these events? A) 4, 6, 7, 3, 2, 5, 1 B) 4, 6, 7, 1, 2, 3, 5 C) 6, 7, 4, 1, 2, 3, 5 D) 2, 4, 6, 7, 1, 3, 5 E) 4, 2, 5, 6, 7, 3, 1
B
81) The all-or-none principle states that A) all stimuli will produce identical action potentials. B) all stimuli great enough to bring the membrane to threshold will produce identical action potentials. C) the greater the magnitude of the stimuli, the greater the magnitude of the action potential. D) only sensory stimuli can activate action potentials. E) only motor stimuli can activate action potentials.
B
85) During repolarization of a neuron A) sodium ions move out of the cell. B) potassium ions move out of the cell. C) potassium ions move into the cell. D) both sodium and potassium ions move into the cell. E) sodium ions move into the cell.
B
102) Type ________ fibers have the largest diameter axons. A) S B) F C) A D) B E) C
C
107) The ion that triggers the release of acetylcholine into the synaptic cleft is A) sodium. B) potassium. C) calcium. D) chloride. E) magnesium.
C
12) Branches that may occur along an axon are called A) telodendria. B) synaptic terminals. C) collaterals. D) hillocks. E) synapses.
C
14) Neurotransmitters ready for release are stored in synaptic A) telodendria. B) terminals. C) vesicles. D) mitochondria. E) neurosomes.
C
19) Neurons that have one axon and one dendrite, with the soma in between, are called A) anaxonic. B) unipolar. C) bipolar. D) tripolar. E) multipolar.
C
2) The ________ nervous system is composed of the brain and spinal cord. A) autonomic B) peripheral C) central D) efferent E) afferent
C
25) In a(n) ________ neuron, the dendrites and axon are continuous or fused. A) multipolar B) anaxonic C) unipolar D) bipolar E) interneuron
C
44) ________ account for roughly half of the volume of the nervous system. A) Axons B) Dendrites C) Neuroglia D) Synapses E) Efferent fibers
C
47) The myelin sheath that covers many CNS axons is formed by A) astrocytes. B) satellite cells. C) oligodendrocytes. D) microglia. E) ependymal cells.
C
56) In the peripheral nervous system, Schwann cells participate in the repair of damaged nerves by A) producing new axons. B) regenerating cell bodies for the neurons. C) forming a cellular cord that directs axonal regrowth. D) clearing away cellular debris. E) producing more satellite cells that fuse to form new axons.
C
60) Ion channels that are always open are called ________ channels. A) active B) gated C) leak D) regulated E) local
C
62) Voltage-gated channels are present A) at the motor end plate. B) on the surface of dendrites. C) in the membrane that covers axons. D) on the soma of neurons. E) along the perikaryon of neurons.
C
66) ________ open or close in response to binding specific molecules. A) Leak channels B) Activated channels C) Chemically gated channels D) Voltage-gated channels E) Voltage-gated and chemically gated channels
C
70) Which of the following is not involved in creating the resting potential of a neuron? A) diffusion of potassium ions out of the cell B) diffusion of sodium ions into the cell C) membrane permeability for sodium ions greater than potassium ions D) membrane permeability for potassium ions greater than sodium ions E) The interior of the plasma membrane has an excess of negative charges.
C
72) Graded potentials A) produce an effect that increases with distance from the point of stimulation. B) produce an effect that spreads actively across the membrane surface. C) may be either a depolarization or a hyperpolarization. D) are often all-or-none. E) cause repolarization.
C
8) The most abundant class of neuron in the central nervous system is A) anaxonic. B) bipolar. C) multipolar. D) pseudopolar. E) unipolar.
C
1) Which of the following is not a function of the nervous system? A) sense the internal and external environments B) integrate sensory information C) coordinate voluntary and involuntary activities D) direct long-term functions, such as growth E) control peripheral effectors
D
10) Clusters of RER and free ribosomes in neurons are called A) neurofilaments. B) neurofibrils. C) perikaryon. D) Nissl bodies. E) microglia.
D
108) Cholinergic synapses release the neurotransmitter A) norepinephrine. B) adrenalin. C) serotonin. D) acetylcholine. E) GABA.
D
11) The axon is connected to the soma at the A) telodendria. B) synaptic terminal. C) collaterals. D) axon hillock. E) synapse.
D
24) ________ neurons are short, with a cell body between dendrite and axon, and occur in special sense organs. A) Multipolar B) Anaxonic C) Unipolar D) Bipolar E) Motor
D
3) The ________ nervous system controls the skeletal muscles. A) sympathetic B) parasympathetic C) afferent D) somatic E) autonomic
D
30) How does blocking retrograde axoplasmic transport in an axon affect the activity of a neuron? A) The neuron becomes unable to produce neurotransmitters. B) The neuron becomes unable to produce action potentials. C) The soma becomes unable to export products to the synaptic terminals. D) The soma becomes unable to respond to changes in the distal end of the axon. E) The neuron becomes unable to depolarize when stimulated.
D
39) Deteriorating changes in the distal segment of an axon as a result of a break between it and the soma is called ________ degeneration. A) neural B) central C) peripheral D) Wallerian E) conduction
D
49) Small, wandering cells that engulf cell debris and pathogens in the CNS are called A) astrocytes. B) satellite cells. C) oligodendrocytes. D) microglia. E) ependymal cells.
D
57) After a stroke, what type of glial cell accumulates within the affected brain region? A) Schwann cells B) satellite cells C) oligodendrocytes D) microglia E) ependymal cells
D
59) At the normal resting potential of a typical neuron, its sodium-potassium exchange pump transports A) 1 intracellular sodium ion for 2 extracellular potassium ions. B) 2 intracellular sodium ions for 1 extracellular potassium ion. C) 3 intracellular sodium ions for 1 extracellular potassium ion. D) 3 intracellular sodium ions for 2 extracellular potassium ions. E) 3 extracellular sodium ions for 2 intracellular potassium ions.
D
63) The sodium-potassium ion exchange pump A) must reestablish ion concentrations after each action potential. B) transports sodium ions into the cell during depolarization. C) transports potassium ions out of the cell during repolarization. D) moves sodium and potassium opposite to the direction of their electrochemical gradients. E) depends on a hydrogen gradient for energy.
D
67) ________ channels open or close in response to physical distortion of the membrane surface. A) Voltage-gated B) Chemically gated C) Active D) Mechanically gated E) Leak
D
7) Which of the following is not a recognized structural classification for neurons? A) anaxonic B) bipolar C) multipolar D) pseudopolar E) unipolar
D
77) If acetylcholine (ACh) causes inhibition of a postsynaptic neuron, to what type of membrane channel did the ACh bind? A) mechanically-regulated channel B) voltage-regulated sodium channel C) voltage-regulated calcium channel D) chemically-regulated potassium channel E) chemically-regulated sodium channel
D
89) Puffer fish poison blocks voltage-gated sodium channels like a cork. What effect would this neurotoxin have on the function of neurons? A) Neurons would depolarize more rapidly. B) Action potentials would lack a repolarization phase. C) The absolute refractory period would be shorter than normal. D) The axon would be unable to generate action potentials. E) None, because the chemically gated sodium channels would still function.
D
100) Which of the following does not influence the time necessary for a nerve impulse to be transmitted? A) length of the axon B) presence or absence of a myelin sheath C) diameter of the axon D) presence or absence of nodes E) whether or not the impulse begins in the CNS
E
105) A neuron that receives neurotransmitter from another neuron is called A) the presynaptic neuron. B) the motor neuron. C) an oligodendrocyte. D) a satellite cell. E) the postsynaptic neuron.
E
111) The effect that a neurotransmitter has on the postsynaptic membrane depends on the A) frequency of neurotransmitter release. B) nature of the neurotransmitter. C) characteristics of the receptors. D) quantity of neurotransmitters released. E) All of the answers are correct.
E
114) Each of the following is an example of a synapse between neurons and effector cells except the junction between a neuron and a(n) A) skeletal muscle cell. B) smooth muscle cell. C) endocrine gland cell. D) exocrine gland cell. E) nerve cell.
E
115) What triggers the release of acetylcholine from a synaptic terminal? A) release of calcium ions from the synaptic vesicles B) graded potentials in the synaptic terminal C) synaptic vesicles fuse to dendrites D) diffusion of sodium ions out of the synaptic terminal E) diffusion of calcium ions into the synaptic terminal
E
15) The site of intercellular communication between a neuron and another cell is the A) telodendria. B) synaptic terminals. C) collateral. D) hillock. E) synapse.
E
20) Neurons that have several dendrites and a single axon are called A) anaxonic. B) unipolar. C) bipolar. D) tripolar. E) multipolar.
E
28) ________ are the most numerous type of neuron in the CNS. A) Sensory neurons B) Motor neurons C) Unipolar neurons D) Bipolar neurons E) Interneurons
E
45) The function of the astrocytes in the CNS includes which of the following? A) adjusting the composition of the interstitial fluid B) guiding neuron development C) maintaining the blood-brain barrier D) repairing damaged neural tissue E) All of the answers are correct.
E
48) ________ line the brain ventricles and spinal canal. A) Astrocytes B) Satellite cells C) Oligodendrocytes D) Microglia E) Ependymal cells
E
5) The efferent division of the peripheral nervous system innervates ________ cells. A) skeletal muscle B) smooth muscle C) heart muscle D) glandular E) All of the answers are correct.
E
50) The neurilemma of axons in the peripheral nervous system is formed by A) astrocytes. B) satellite cells. C) oligodendrocytes. D) microglia. E) Schwann cells.
E
53) Extensive damage to oligodendrocytes in the CNS could result in A) loss of the structural framework of the brain. B) a breakdown of the blood-brain barrier. C) inability to produce scar tissue at the site of an injury. D) decreased production of cerebrospinal fluid. E) loss of sensation and motor control.
E
55) When pressure is applied to neural tissue, all of the following effects are possible except A) a decrease in blood flow. B) a decrease in available oxygen. C) a change in neuron excitability D) glial cells degenerate. E) neurons are triggered to divide.
E
6) The axoplasm of the axon contains which of the following? A) neurotubules B) mitochondria C) vesicles D) neurofibrils E) All of the answers are correct.
E
68) Any stimulus that opens a ________ ion channel will produce a graded potential. A) voltage-gated B) chemically gated C) sodium D) mechanically gated E) All of the answers are correct.
E
69) If the permeability of a resting axon to sodium ion increases, A) the membrane potential will repolarize. B) the membrane potential will hyperpolarize. C) inward movement of sodium ion will increase. D) outward movement of sodium ion will decrease. E) inward movement of sodium will increase and the membrane will depolarize.
E
74) Ions can move across the plasma membrane in which of the following ways? A) through voltage-gated channels as in the action potential B) through passive or leak channels C) by ATP-dependent ion pumps like the sodium-potassium exchange pump D) through chemically gated channels as in neuromuscular transmission E) All of the answers are correct.
E
75) Raising the potassium ion concentration in the extracellular fluid surrounding a nerve cell will have what effect? A) depolarize it B) hyperpolarize it C) increase the magnitude of the potassium equilibrium potential D) decrease the magnitude of the potassium equilibrium potential E) both hyperpolarize it and decrease the magnitude of the potassium equilibrium potential
E
78) A stimulus that changes a postsynaptic neuron's membrane from resting potential to -85 mV is a(n) ________ stimulus. A) excitatory B) depolarizing C) temporal D) saltatory E) inhibitory
E
86) How would a chemical that prevents the opening of voltage-regulated Na+ channels affect the function of a neuron? A) The neuron will only be able to hyperpolarize. B) The neuron will depolarize more rapidly. C) Action potentials will lack a repolarization phase. D) The neuron will automatically and repeatedly produce graded potentials. E) The neuron will only be capable of producing graded potentials.
E
9) The cytoplasm that surrounds the nucleus of a neuron is called the A) protoplasm. B) nucleoplasm. C) sarcoplasm. D) neuroplasm. E) perikaryon.
E