Chapter 7 multiple choice
A bundle of axons in the PNS is contained within a/an _____. A) nerve, B) bundle, C) tract, D) neuron
A) nerve
Norepinephrine activate postsynaptic cells by A) inhibition of adenylate cyclasE)B) increased Ca2+ influx into the target cell. C) inhibition of calmodulin. D) increased production of cyclic AMP.
B) increased Ca2+ influx into the target cell.
Myelinated axons transmit action potentials more rapidly than unmyelinated axons. A) True, B) FalsE)
A) True
Norepinephrine binding to a receptor stimulates the activity of adenylate cyclase. A) True, B) False.
A) True
The greater the diameter of an axon, the faster the action potential will be conducted. A) True, B) False
A) True
The membrane becomes more negative during hyperpolarization. A) True, B) False
A) True
The nicotinic ACh receptor is a ligand-gated channel. A) True, B) False.
A) True
Once an EPSP is created on the postsynaptic neuron, a new action potential will be produced down the axon. A) True, B) False.
A) True,
The gap of exposed axon in the myelin sheath is the _________. A) neurilemma, B) node of Ranvier, C) sheath of Schwann, D) white matter, E) gray matter.
B) node of Ranvier,
Graded potentials that arrive at postsynaptic neurons are called ________ if they make that cell more likely to fire.
excitatory
The addition of stimuli arriving in rapid succession to produce an action potential is called ________.
temporal summation
The time during which an excitable membrane cannot respond to further stimulation regardless of the stimulus strength is the ________.
absolute refractory period
The minimum amount of stimulus required to depolarize an excitable membrane and generate an action potential is known as the ________.
Threshold -55mV
All cells have a membrane potential. A) True, B) FalsE)
A) True
Both excitatory and inhibitory postsynaptic potentials undergo summation. A) True, B) False.
A) True
The average resting membrane potential of an axon is __________. A) -70mV, B) -85mV, C) 0 mV, D) +30mV.
A) -70mV
"An axon will depolarize only if the membrane potential reaches -55mV". This statement supports the "_______________ law". A) All-or-none, B) recruitment, C) graduated, D) threshold, E) decrement.
A) All-or-none
Predict: In the membrane of a resting nerve cell, when chemically gated Cl- channels open, A) Cl- ions enter the cell. B) Cl- ions leave the cell. C) the cell becomes depolarized. D) Cl- ions enter the cell and the cell becomes depolarized. E) Cl- ions leave the cell and the cell becomes depolarized.
A) Cl- ions enter the cell
How would the absolute refractory period be affected if voltage-gated sodium channels remained inactivated? A) It would be longer than normal. B) It would be shorter than normal. C) It would be the same whether the channels remained inactivated or not. D) None of the answers are correct.
A) It would be longer than normal.
When more action potentials arrive at the axon terminal, how are neurotransmitters affected? A) More molecules are released into the synapse. B) Different molecules are released into the synapse. C) Fewer molecules are released into the synapse. D) There is no effect—all signals are identical.
A) More molecules are released into the synapse
Excitatory neurotransmitters of the CNS usually act by opening ________ channels. A) Na+ B) K+ C) Cl- D) H+ E) Ca2
A) Na+
Depolarization in an action potential is due to A) Na+ flow into the cell only. B) Na+ flow out of the cell only. C) K+ flow out of the cell only. D) K+ flow into the cell only. E) Na+ flow out of the cell and K+ flow into the cell.
A) Na+ flow into the cell only.
The myelin sheaths of PNS neurons are produced by _________. A) Schwann cells, B) oligodendrocytes, C) ependymal cells, D) leukocytes.
A) Schwann cells
All axons in the PNS have a myelin sheath. A) True, B) False.
A) True
An EPSP is conducted decrementally to the axon hillock, where voltage-gated Na+ and K+ channels are opened to create an action potential in the first segment of the axon. A) True, B) False.
A) True
An inhibitory postsynaptic potential would be produced by a neurotransmitter opening Cl- channels. A) True, B) False.
A) True
Axons use ATP to produce an action potential. A) True, B) False
A) True
Both depolarization and repolarization are produced by the diffusion of ions down their concentration gradient. A) True, B) False.
A) True
The basis of neural integration is A) addition of postsynaptic potentials overlapping in time and space. B) command signals from central pattern generators. C) spontaneous activity in pacemaker neurons. D) the area under the curve of postsynaptic potentials overlapping in time and space
A) addition of postsynaptic potentials overlapping in time and space.
The brain and spinal cord together compose the A) central nervous system. B) autonomic division system. C) somatic motor division of the nervous system. D) peripheral nervous system. E) visceral nervous system.
A) central nervous system.
Chemical synapses _________________. A) have a delayed impulse transmission. B) utilize gap junctions. C) occur when two nerve cells are in direct contact with each other. D) do not require the release of neurotransmitters.
A) have a delayed impulse transmission
Which of the following would produce an IPSP on the postsynaptic membrane? A) influx of Na+ ions, B) opening of Ca2+ channels into the neuron, C) outflow of K+ ions, D) opening of Cl- channels into the neuron
A) influx of Na+ ions
Which of the following is NOT a structural classification of neurons? A) motor neuron, B) bipolar neuron, C) multipolar neuron, D) unipolar neuron.
A) motor neuron
White matter is ______________. A) myelinated axons in the CNS, B) myelinated axons in the PNS, C) nonmyelinated cell bodies and dendrites in the CNS, D) nonmyelinated axons in the CNS.
A) myelinated axons in the CNS
The ability of a neuron to transmit charge through its cytoplasm is called cable properties is generally __________. A) not that good, B) really good, C) nonexistent.
A) not that good,
Temporal summation A) occurs when a single neuron releases neurotransmitter rapidly. B) occurs because of the convergence of many neurons on a single postsynaptic cell. C) only involves excitatory postsynaptic potentials. D) only involves inhibitory postsynaptic potentials.
A) occurs when a single neuron releases neurotransmitter rapidly.
Which ion(s) is/are higher in concentration inside the cell compared to outside? A) potassium B) sodium C) chloride D) calcium E) More than one of the answers is correct.
A) potassium
What type of neuron may its cell body in the CNS? A) sensory neuron, B) association neuron, C) motor neuron, D) A and B, E) B and C.
A) sensory neuron
Muscarinic ACh receptors are NOT found on _____. A) skeletal muscle B) smooth muscle C) contactile cardiac muscle D) glands.
A) skeletal muscle
All of the following must occur before a second action potential can begin, EXCEPT A) the Na+ and K+ ions that moved in/out of the cell must move back to their original compartments. B) the Na+ inactivation gate must open and the Na+ activation gate must close. C) the absolute refractory period must occur. D) the Na+ and K+ ions that moved in/out of the cell must move back to their original compartments; the Na+ inactivation gate must open; and the Na+ activation gate must close. E) None of the answers are correct.
A) the Na+ and K+ ions that moved in/out of the cell must move back to their original compartments.
The ________ "law" states that the properties of the action potential are independent of the relative strength of the depolarizing stimulus.
All-or-none law
A chemical synapse ALWAYS includes which of the following? 1. axon terminal 2. presynaptic cell 3. synaptic cleft 4. postsynaptic cell 5. dendrite A) 1, 2, 3, 4, 5 B) 1, 2, 3, 4 C) 2, 3, 4 D) 2, 3, 4, 5 E) 1, 3, 4
B) 1, 2, 3, 4
The following are steps involved in transmission at the cholinergic synapse: 1. Chemically regulated ion channels on the postsynaptic membrane are activated. 2. Calcium ions enter the axon terminal. 3. An action potential depolarizes the axon terminal at the presynaptic membrane. 4. Acetylcholine is released from storage vesicles by exocytosis. 5. Acetylcholine binds to receptors on the postsynaptic membrane. The correct sequence for these events is A) 4, 2, 1, 5, 3. B) 3, 2, 4, 5, 1. C) 2, 4, 1, 3, 5. D) 2, 5, 4, 1, 3. E) 1, 2, 3, 4, 5.
B) 3, 2, 4, 5, 1
The following are the main steps in the generation of an action potential: 1. sodium channels are inactivated 2. more voltage-regulated 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 further depolarization occurs The proper sequence of these events is A) 4, 6, 7, 3, 2, 5, 1. B) 4, 6, 7, 1, 2, 5, 3. 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) 4, 6, 7, 1, 2, 5, 3
A nerve contains a bundle of axons in the CNS. A) True, B) False.
B) False
A neuron will depolarize due to the influx of K+. A) True, B) False.
B) False
Action potentials frequency encodes stimulus intensity. A) True, B) False
B) False
Ligand-gated channels, when activated, allow only Na+ to move into the neuron. A) True, B) False
B) False
Nicotinic receptors utilize G-proteins to regulate the opening of ion channels. A) True, B) False.
B) False
Somatic motor neurons innervate involuntary effectors. A) True, B) False
B) False
A lack of extracellular Ca2+ would cause increased release of neurotransmitters. A) True, B) False.
B) False.
In a ligand-gated channel, the neurotransmitter receptor and the channel are separate proteins. A) True, B) False.
B) False.
When voltage-gated K+ channels of a resting neuron open, A) K+ enters the neuron. B) K+ leaves the neuron. C) the neuron depolarizes. D) K+ enters the neuron and the neuron depolarizes. E) K+ leaves the neuron and the neuron depolarizes.
B) K+ leaves the neuron.
If a hyperpolarizing graded potential and a depolarizing graded potential of similar magnitudes arrive at the trigger zone at the same time, what is most likely to occur? A) An action potential is fired off more quickly than usual. B) Nothing. They will cancel each other out. C) The cell becomes hyperpolarized. D) The cell becomes easier to excite. E) The cell dies.
B) Nothing. They will cancel each other out.
Cholinergic synapses use ____ as the neurotransmitter. A) norepinephrine B) acetylcholine, C) dopamine, D) serotonin, E) endocannabinoids.
B) acetylcholine
The all-or-none "law" states that A) all stimuli will produce identical action potentials. B) all stimuli great enough to bring the membrane to threshold will produce action potentials of identical magnitude. C) the greater the magnitude of the stimuli, the greater the intensity of the action potential. D) only sensory stimuli can activate action potentials. E) only motor stimuli can activate action potentials.
B) all stimuli great enough to bring the membrane to threshold will produce action potentials of identical magnitude.
Sensory neurons ______. A) are multipolar and carry impulses toward the CNS, B) are usually unipolar and carry impulses toward the CNS, C) are sometimes bipolar and carry impulses away from the CNS, D) are multipolar and carry impulses away from the CNS.
B) are usually unipolar and carry impulses toward the CNS,
Exocrine glands, smooth muscles, and cardiac muscles are controlled by the A) central nervous system. B) autonomic nervous system. C) somatic motor division. D) peripheral nervous system. E) enteric nervous system.
B) autonomic nervous system.
Neurotransmitters are released from the A) dendrites. B) axon terminals. C) collaterals. D) axon hillock. E) synapse.
B) axon terminals.
Neurotransmitter release would be inhibited by ___________________. A) repolarization of the axon terminal. B) blocking Ca2+ influx in the axon terminal. C) blocking repolarization of the axon terminal. D) stimulating protein kinase activity, E) excitation at an axon terminal.
B) blocking Ca2+ influx in the axon terminal.
A neuron is experiences a low grade stimulus. When the intensity of the stimulus is increased, the frequency of APs observed should _____________. A) increase, B) decrease, C) stay the same.
B) decrease
Botulism toxin prevents release of ACh. It would thus generally cause: _______. A) some synapses to communicate poorly or not at all. B) excitation of some synapses.
B) excitation of some synapses.
Conduction occurs along an axon because A) outflow of K+ triggers the adjacent channels to open. B) inflow of Na+ triggers the adjacent channels to open. C) once Na+ enters the cell, the entire membrane depolarizes simultaneously. D) axonal transport "walks" voltage changes along the membrane.
B) inflow of Na+ triggers the adjacent channels to open.
What is present at the axon hillock that allows the production of action potentials? A) voltage-gated channels, B) ligand-gated channels, C) muscarinic receptors, D) chemical-gated channels.
B) ligand-gated channels,
In order to signal a stronger stimulus, action potentials become A) higher in amplitude only. B) more frequent only. C) longer-lasting only. D) higher in amplitude and more frequent. E) higher in amplitude and longer-lasting
B) more frequent only.
Spatial summation refers to A) electrical signals reaching neurons from outer space. B) multiple graded potentials arriving at one location simultaneously. C) repeated graded potentials reaching the trigger zone one after the other. D) suprathreshold potentials triggering action potentials that are extra large. E) All of the answers are correct.
B) multiple graded potentials arriving at one location simultaneously.
Acetylcholine usually induces an excitatory postsynaptic potential when binding to ________ receptors and an inhibitory postsynaptic potential when binding to some ____________ receptors. A) NMDA, nicotinic, B) nicotinic, muscarinic, C) muscarinic, NMDA, D) muscarinic, nicotinic
B) nicotinic, muscarinic
Spatial summation A) occurs when a single neuron releases neurotransmitter rapidly. B) occurs because of the convergence of many neurons on a single postsynaptic cell. C) only involves excitatory postsynaptic potentials. D) only involves inhibitory postsynaptic potentials.
B) occurs because of the convergence of many neurons on a single postsynaptic cell.
The portions of a neuron that extend off of the roughly spherical cell body are usually collectively called A) protrusions. B) processes. C) prostheses. D) projections.
B) processes.
Inhibitory postsynaptic potentials (IPSPs) A) result in local depolarizations. B) result in local hyperpolarizations. C) increase membrane permeability to sodium ions. D) prevent the escape of potassium ions. E) prevent the escape of calcium ions.
B) result in local hyperpolarizations.
Conduction of an action potential in a myelinated axon is called ______. A) point to point conduction. B) saltatory conduction. C) refractory conduction. D) cable conduction. E) superconduction.
B) saltatory conduction.
Calcium is important in the synapse because it A) is necessary for acetylcholine synthesis. B) signals the exocytosis of the neurotransmitter. C) binds to receptors on the postsynaptic cell, opening ion channels, and triggering graded potentials. D) leaves the axon terminal, hyperpolarizing the cell.
B) signals the exocytosis of the neurotransmitter.
Autonomic motor neurons are subdivided into the A) visceral and somatic divisions. B) sympathetic and parasympathetic divisions. C) central and peripheral divisions. D) visceral and enteric divisions. E) somatic and enteric divisions.
B) sympathetic and parasympathetic divisions.
When a second EPSP arrives at a single synapse before the effects of the first have disappeared, what occurs? A) spatial summation B) temporal summation C) inhibition of the impulse D) hyperpolarization E) decrease in speed of impulse transmission
B) temporal summation
The minimum depolarization needed to open Na+ gates is called the _____________. A) repolarization, B) threshold, C) refractory period, D) All-or-none law.
B) threshold
on channels that open in response to depolarization are called A) ion-gated channels. B) voltage-gated channels. C) stimulation-gated channels. D) potential-gated channels.
B) voltage-gated channels
The binding of a neurotransmitter to its receptor protein causes ion channels to open in the post-synaptic membranE)What type of gates are these? A) chemically-regulated gates B) voltage-regulated gates C) ligand-regulated gates D) Chemically-regulated gates and ligand-regulated gates are correct.
B) voltage-regulated gates
Identify the FALSE statement. A) EPSPs that reach threshold can initiate an action potential. B) The trigger zone is the integrating center of the neuron. C) IPSPs depolarize the membrane. D) All of the statements are true.
C) IPSPs depolarize the membrane.
Repolarization in an action potential is due primarily to A) Na+ flow in the cell only. B) Na+ flow out of the cell only. C) K+ flow out of the cell only. D) K+ flow into the cell only. E) Na+ flow out of the cell and K+ flow into the cell.
C) K+ flow out of the cell only.
The most influential determinant of the resting potential of all cells is A) Ca2+ concentration in the blood and interstitial fluid. B) Na+ concentration in the blood and interstitial fluid. C) K+ gradient between the interstitial fluid and cytoplasm. D) K+ concentration inside cells. E) Na+ concentration inside cells.
C) K+ gradient between the interstitial fluid and cytoplasm.
Blocking ____________ channels would prevent neuron depolarization. A) K+, B) Cl- , C) Na+ , D) Mg2+ , E) Ca+2
C) Na+
During an action potential ___________ A) Na+ efflux causes depolarization. B) K+ influx causes repolarization. C) Na+ influx causes depolarization. D) K+ influx causes after-hyperpolarization. E) Na+ efflux and K+ causes depolarization.
C) Na+ influx causes depolarization
______________ establishes the proper concentrations of ions in cells. A) hyperpolarization, B) the all-or-none-law, C) Na+/K+ pumps, D) the refractory period, E) ion channels.
C) Na+/K+pumps
When more action potentials arrive at the axon terminal, how is the postsynaptic cell affected? A) Neurotransmitter release increases, but does not change the graded potentials that follow. B) Neurotransmitter release does not change, thus the postsynaptic cell behaves the same way it always behaves. C) Neurotransmitter release increases, thereby increasing the frequency or magnitude of graded potentials in the postsynaptic cell. D) Neurotransmitter release does not change, but voltages applied to the postsynaptic cell increase.
C) Neurotransmitter release increases, thereby increasing the frequency or magnitude of graded potentials in the postsynaptic cell.
What stops depolarization in an action potential? A) The K+ gate closes. B) The Na+ activation gate opens. C) The Na+ inactivation gate closes. D) The Na+ inactivation gate opens. E) The sodium activation gate closes.
C) The Na+ inactivation gate closes.
Predict: Action potentials would be conducted most rapidly by _____. A) a 10 mm diameter myelinated axon, B) a 10 mm diameter unmyelinated axon, C) a 40 mm diameter myelinated axon, D) a 40 mm diameter unmyelinated axon.
C) a 40 mm diameter myelinated axon
Which division of the nervous system innervates involuntary effectors? A) central nervous system, B) somatic nervous system, C) autonomic nervous system, D) associative nervous system.
C) autonomic nervous system
At what region of the neuron are action potentials produced? A) dendrites B) cell body, C) axon hillock, D) all of these.
C) axon hillock
Which of the following is location where action potentials generally originate? A) dendrites B) cell body C) axon hillock D) synaptic cleft E) synaptic bouton
C) axon hillock
The site of information integration in the nervous system is the A) chemical synapse. B) electrical synapse. C) axon hillock. D) dendritic membrane. E) axon terminal.
C) axon hillock.
Action potentials are primarily associated with the membranes of A) dendrites only. B) cell bodies only. C) axons only. D) dendrites and axons. E) cell bodies and axons
C) axons only
Local anesthetics (like lidocaine) block conduction of action potentials in neurons by ________. A) inhibiting the release of acetylcholine, B) binding to potassium channels, C) binding to sodium channels, D) binding to calcium channels.
C) binding to sodium channels
The ion that is most directly responsible for the release of acetylcholine into the synaptic cleft is A) sodium. B) potassium. C) calcium. D) chloride. E) zinc.
C) calcium.
In a myelinated axon, V-G Na+ channels are ________. A) along the whole length of the axon. B) every 5 mm. C) concentrated at the nodes of Ranvier. D) less numerous at the nodes of Ranvier.
C) concentrated at the nodes of Ranvier.
The multiple thin, branched structures on a neuron whose main function is to receive incoming signals are the A) cell bodies. B) axons. C) dendrites. D) somata. E) None of the answers are correct.
C) dendrites.
An excitatory postsynaptic potential (EPSP) A) depolarizes a neuron, decreasing the likelihood of an action potential. B) hyperpolarizes a neuron, decreasing the likelihood of an action potential. C) depolarizes a neuron, increasing the likelihood of an action potential. D) hyperpolarizes a neuron, increasing the likelihood of an action potential.
C) depolarizes a neuron, increasing the likelihood of an action potential.
What is the predominant effect of stimulation of nicotinic channels? A) excitation due to outflow of K+ ions, B) inhibition due to outflow of K+ ions, C) excitation due to influx of Na+ ions, D) excitation due to influx of Cl- ions, E) excitation due to influx of Ca+2 ions.
C) excitation due to influx of Na+ ions
If the resting axon's membrane becomes more permeable to potassium ions, A) the inside of the membrane will become more positively charged. B) the membrane will depolarize more rapidly. C) it will take a stimulus of larger magnitude to initiate an action potential. D) the hyperpolarization at the end of the action potential will not occur.
C) it will take a stimulus of larger magnitude to initiate an action potential.
Which of the following is NOT a functional classification of neurons? A) motor or efferent, B) interneuron or association, C) multipolar, D) sensory or afferent.
C) multipolar neuron
Interneurons are found A) only in the brain. B) only in the spinal cord. C) only in the CNS* D) throughout the nervous system. E) only in spinal nerves.
C) only in the CNS*
Which ion's movements is responsible for repolarization in axons? A) influx of K+, B) influx of Na+, C) outward diffusion of K+, D) outward diffusion of Na+
C) outward diffusion of K+
The membrane of resting nerve cells is more permeable to ____________ ions than ____________ ions. A) sodium, potassium, B) calcium, potassium, C) potassium, sodium, D) chloride, potassium.
C) potassium, sodium
To increase the amount of neurotransmitter released onto a postsynaptic cell, the presynaptic cell would have to A) send action potentials with higher voltage (higher amplitude). B) send action potentials with longer durations. C) send action potentials with higher frequency. D) do nothing; no change is possible since the all-or-none law is in effect.
C) send action potentials with higher frequency.
The region where the axon terminal meets its target cell is called the A) collateral. B) hillock. C) synapse. D) nerve. E) dendrites.
C) synapse.
The total amount of neurotransmitter released at the axon terminal is directly related to A) the amplitude of the action potential. B) the length of the axon. C) the total number of action potentials. D) the amplitude of the graded potential.
C) the total number of action potentials.
Which of the following is NOT true of EPSPs? A) they are graded responses B) they are capable of summation C) they have a refractory period D) they are initiated by neurotransmitters, E) they are initiated by mechanical stimuli.
C) they have a refractory period
Norepinephrine and epinephrine derived from: A) glucose B) fatty acids C) amino acids D) ATP.
C)amino acids
Once the stimulus alters the receptor on the cell's membrane, what happens next? A) Ion channels open, allowing ions to enter or exit. B) The membrane permeability is altered. C) A second messenger is activated on the inside of the cell. D) Any of these actions could happen next.
D) Any of these actions could happen next
When voltage-gated Na+ channels of a resting neuron open, A) Na+ enters the neuron. B) Na+ leaves the neuron. C) the neuron depolarizes. D) Na+ enters the neuron and the neuron depolarizes. E) Na+ leaves the neuron and the neuron depolarizes
D) Na+ enters the neuron and the neuron depolarizes
Tetrodotoxin is a toxin that blocks voltage-gated sodium channels. What effect does this substance have on the function of neurons? A) Neurons depolarize more rapidly. B) Action potentials lack a repolarization phase. C) The absolute refractory period is shorter than normal. D) The neuron is not able to propagate action potentials. E) The toxin does not interfere with neuron function because the voltage-regulated sodium channels would still function.
D) The neuron is not able to propagate action potentials.
Information coming into the central nervous system is transmitted along ________ neurons. A) afferent B) sensory C) efferent D) afferent and sensory E) sensory and efferent
D) afferent and sensory
"V-G Na+ channels are in an inactived state", and "V-G K+ channels are open" describes: _______. A) repolarization, B) depolarization, C) hyperpolarization, D) all of these, E) none of these.
D) all of these
Neurotransmitters ________. A) are released by endocytosis. B) all bind to the same receptor. C) often regulate ion channels. D) are actively transported across the synaptic cleft.
D) are actively transported across the synaptic cleft.
The axon is connected to the cell body by the A) myelin sheath. B) axon terminal. C) collaterals. D) axon hillock. E) synapse.
D) axon hillock.
Acetylcholine: A) is always an excitatory neurotransmitter. B) can bind to adrenergic receptors. C) is an inhibitory neurotransmitter released by motor neurons. D) can bind to nicotinic receptors.
D) can bind to nicotinic receptors
When comparing action potentials to graded potentials, an/two important distinguishing characteristic/s is/are A) graded potentials can undergo summation. B) action potentials can undergo summation. C) that the rate of action potentials is limited by the refractory period. D) graded potentials can undergo summation and the rate of action potentials is limited by the refractory period. E) action potentials can undergo summation and the rate of action potentials is limited by the refractory period.
D) graded potentials can undergo summation and the rate of action potentials is limited by the refractory period.
The afferent and efferent axons together are part of the A) central nervous system. B) autonomic division system. C) somatic motor division of the nervous system. D) peripheral nervous system. E) visceral nervous system.
D) peripheral nervous system.
What is present at the axon hillock that allows the production of action potentials? A) voltage-gated channels, B) ligand-gated channels, C) muscarinic receptors, D) chemical-gated channels. What is NOT true of conduction through dendrites and cell bodies of neurons? A) they are EPSPs, B) they are spread by cable properties, C) they can summate to reach threshold, D) they are action potentials.
D) they are action potentials.
The resting membrane potential results from A) uneven distribution of ions across the cell membrane only. B) differences in membrane permeability to Na+ and K+ only. C) activity of the sodium/potassium pump only. D) uneven distribution of ions across the cell membrane and differences in membrane permeability to Na+ and K+. E) None of the answers are correct.
D) uneven distribution of ions across the cell membrane and differences in membrane permeability to Na+ and K+.
Graded potentials may A) initiate an action potential. B) depolarize the membrane to the threshold voltage. C) hyperpolarize the membrane. D) be called EPSPs or IPSPs. E) All of the statements are true.
E) All of the statements are true.
When two or more graded potentials arrive at the trigger zone, which of the following could happen? A) An excitatory and inhibitory signal can cancel each other out. B) Two excitatory stimuli may be additive, and summation could occur. C) Two inhibitory stimuli may be additive, resulting in lower excitability. D) An excitatory and inhibitory signal can cancel each other out and two excitatory stimuli may be additive, and summation could occur. E) An excitatory and inhibitory signal can cancel each other out; two excitatory stimuli may be additive, and summation could occur; and two inhibitory stimuli may be additive, resulting in lower excitability.
E) An excitatory and inhibitory signal can cancel each other out; two excitatory stimuli may be additive, and summation could occur; and two inhibitory stimuli may be additive, resulting in lower excitability.
Hyperpolarization in the postsynaptic cell may be caused by ____________. A) excitatory postsynaptic potentials. B) inhibitory postsynaptic potentials. C) movement of K+ out of the cell. D) A and C are correct. E) B and C are correct.
E) B and C are correct
Neurotransmitter is stored and released from A) axon terminals only. B) axon varicosities only. C) dendritic spines only. D) cell bodies only. E) axon terminals and axon varicosities.
E) axon terminals and axon varicosities.
Some neurotoxins work essentially the same way as some local anesthetics, which is to A) inactivate the enzyme that destroys the neurotransmitter only. B) bind to Na+ channels and inactivate them only. C) prevent depolarization by blocking Na+ entry into the cell only. D) inactivate the enzyme that destroys the neurotransmitter and bind to Na+ channels and inactivate them. E) bind to Na+ channels and inactivate them and prevent depolarization by blocking Na+ entry into the cell.
E) bind to Na+ channels and inactivate them and prevent depolarization by blocking Na+ entry into the cell.
Conduction speed would be enhanced by A) myelin. B) altering extracellular sodium concentration. C) increasing the temperature. D) altering extracellular potassium concentration. E) myelin and increasing the temperature.
E) myelin and increasing the temperature.
Chemicals that stimulate action potentials in postsynaptic cells are called A) hormones. B) enzymes. C) ion channels. D) neurotrophins. E) neurotransmitters.
E) neurotransmitters
The sodium-potassium exchange pump A) must re-establish 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 in the direction of their chemical gradients. E) requires ATP to function.
E) requires ATP to function.
Which of the following is NOT true of nicotinic channels? A) The binding of ACh allows diffusion of Na+ into of the neuron. B) they generate EPSPs. C)they generate graded potentials. D) they can contribute to summation, E)all of these are true
E)all of these are true
At a(n) ________ synapse, a neurotransmitter is released to affect the postsynaptic cell.
chemical
The two types of electrical signals in neurons are ________.
graded potentials and action potentials
Graded potentials that arrive at postsynaptic neurons are called ________ if they make that cell less likely to fire.
inhibitory
A) dendrites B) axon C) cell body may be covered with myelin receive(s) most of the incoming synapses A occupy(ies) the least amount of cell volume make(s) proteins necessary for repair of damaged neuron where most graded potentials originate location of voltage-gated ion channels
may be covered with myelin B)axon receive(s) most of the incoming synapses A)dendrites occupy(ies) the least amount of cell volume C)cell body make(s) proteins necessary for repair of damaged neuron C)cell body where most graded potentials originate A) dendrites location of voltage-gated ion channels B)axon
A) graded potential B) action potential C) both may be hyperpolarizing A) graded potential originate(s) at the trigger zone B)action potential originate(s) on dendrites and cell bodies A)graded potential can involve ion channels regulated by chemicals A)graded potential require(s) a minimum stimulus to occur B)action potential size increases if stimulus strength increases A)graded potential may result(s) from influx of sodium C)both
may be hyperpolarizing A) graded potential originate(s) at the trigger zone B)action potential originate(s) on dendrites and cell bodies A)graded potential can involve ion channels regulated by chemicals A)graded potential require(s) a minimum stimulus to occur B)action potential size increases if stimulus strength increases A)graded potential may result(s) from influx of sodium C)both
The gaps between adjacent Schwann cells on an axon are called ________.
nodes of Ranvier
The addition of several stimuli arriving from different locations on the same cell to produce an action potential is called ________.
spatial summation
When two or more graded potentials arrive at the trigger zone within a short period of time, their effects are additive and ________ occurs.
summation
