Chapter 12
________ are nerves that connect to the brain.
Cranial nerves
The ________ division of the peripheral nervous system brings sensory information to the central nervous system.
afferent
The ________ principle states that the size and speed of the action potential are independent of the stimulus strength.
all-or-none
Products from the soma of a neuron are transported to the synaptic terminals by ________ axoplasmic transport.
anterograde
The buildup of depolarization when EPSPs arrive in rapid succession is called ________ summation.
temporal
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
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
________ neurons are small and have no anatomical features that distinguish dendrites from axons. A) Multipolar B) Anaxonic C) Unipolar D) Bipolar E) Sensory
b
________ neurons form the afferent division of the PNS. A) Visceral sensory B) Sensory C) Neural sensory D) Somatic sensory E) Motor
b
drenergic synapses release the neurotransmitter A) acetylcholine. B) norepinephrine. C) dopamine. D) serotonin. E) GABA
b
The site in the neuron where EPSPs and IPSPs are integrated is the A) chemical synapse. B) electrical synapse. C) axon hillock. D) dendritic membrane. E) synaptic terminal.
c
Type ________ fibers have the largest diameter axons. A) S B) F C) A D) B E) C
c
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
At a(n) ________ synapse, a neurotransmitter is released to stimulate the postsynaptic membrane.
chemical
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
The ________ nervous system controls the skeletal muscles. A) sympathetic B) parasympathetic C) afferent D) somatic E) autonomic
d
The axon is connected to the soma at the A) telodendria. B) synaptic terminal. C) collaterals. D) axon hillock. E) synapse.
d
________ line the brain ventricles and spinal canal. A) Astrocytes B) Satellite cells C) Oligodendrocytes D) Microglia E) Ependymal cells
e
The ________ division carries motor commands to muscles and glands.
efferent
In a(n) ________ synapse, current flows directly between cells.
electrical
The sum of the electrical and chemical forces acting on an ion is known as its ________.
electrochemical gradient
The tiny gaps between adjacent Schwann cells are called ________.
nodes of ranvier
The buildup of depolarization when EPSPs arrive at several places on the neuron is called ________ summation.
spatial
The minimum stimulus required to trigger an action potential is known as the ________.
threshold
Regions of the CNS with an abundance of myelinated axons constitute the ________ matter.
white
The basic functional unit of the nervous system is the ________.
neuron
The basic functional unit of the nervous system are cells called ________.
neurons
________ carry sensory information to the CNS
Afferent neurons
________ carry motor information to peripheral effectors.
Efferent neurons
________ provide information about the external environment
Exteroceptors
________ monitor the digestive, respiratory, cardiovascular, urinary, and reproductive systems.
Interoceptors
________ monitor the position of skeletal muscles and joints.
Proprioceptors
________ are nerves that connect to the spinal cord.
Spinal nerves
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
Axons terminate in a series of fine extensions known as A) telodendria. B) terminals. C) collaterals. D) dendrites. E) synapses.
a
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
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
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
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) the same in all because of the all-or-none principle
a
Integral membrane proteins that connect electrical synapses are called A) connexons. B) receptors. C) desmosomes. D) sodium channels. E) synapsins.
a
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
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
Sensory information from skeletal muscles travels over ________ fibers. A) type A B) type B C) type C D) type D E) type E
a
Sensory neurons of the PNS are A) unipolar. B) bipolar. C) anaxonic. D) multipolar. E) tripolar
a
Summation that results from the cumulative effect of multiple synapses at multiple places on the neuron is designated A) spatial summation. B) temporal summation. C) inhibition of the impulse. D) hyperpolarization. E) impulse transmission.
a
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
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
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
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
Voltage-gated sodium channels have both an activation gate and a(n) ________ gate. A) inactivation B) ion C) swinging D) repolarization E) threshold
a
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
Which of the following activities or sensations is not monitored by interoceptors? A) sight B) taste C) activities of the digestive system D) cardiovascular activities E) urinary activities
a
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
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
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) In the after-hyperpolarization phase, membrane potential approaches the potassium equilibrium potential. E) Repolarization occurs as potassium ions leave the axon.
a
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
Which type of synapse is most common in the nervous system? A) chemical B) electrical C) mechanical D) processing E) radiative
a
________ neurons are the most common class in the CNS. A) Multipolar B) Anaxonic C) Unipolar D) Bipolar E) Sensory
a
The period during which an excitable membrane cannot respond to further stimulation is the ________.
absolute refractory period
The ________ nervous system provides involuntary regulation of smooth muscle, cardiac muscle, and glandular activity.
autonomic
The plasma membrane of an axon is called the ________.
axolemma
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
Glial cells that surround the neurons in ganglia are A) astrocytes. B) satellite cells. C) oligodendrocytes. D) microglia. E) ependymal cells.
b
IPSPs (inhibitory postsynaptic potentials) A) are local depolarizations. B) are local hyperpolarizations. C) increase membrane permeability to sodium ions. D) block the efflux of potassium ions. E) block the efflux of calcium ions.
b
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
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
If the potassium permeability of a resting neuron increases above the resting permeability, what effect will this have on the transmembrane potential? 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
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
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
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
Opioids relieve pain by blocking the release of A) substance O. B) substance P. C) substance Q. D) substance X. E) None of the answers are correct.
b
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
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
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. The proper sequence of these events is 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
The following are the steps involved in transmission at a cholinergic synapse. 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 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 synaptic terminal. The correct sequence for these events is 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
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
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
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
Which of the following interactions between electrical and chemical gradients does not lead to 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 out of the cell. C) Chemical forces tend to drive potassium ions out of the cell. D) Potassium ions are attracted to the negative charges inside the cell. E) Potassium ions are repulsed by positive charges outside the cell.
b
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
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
A postsynaptic neuron will have an Excitatory Postsynaptic Potential (EPSP) when A) chemically-regulated potassium channels are open and potassium is diffusing out of the cell. B) more calcium ions than usual diffuse into the neuron. C) chemically-regulated sodium channels are open and sodium is diffusing into the cell. D) the neuron is hyperpolarized. E) more potassium ions than usual diffuse out of the neuron.
c
After acetylcholinesterase acts, the synaptic terminal A) reabsorbs the acetylcholine. B) reabsorbs the acetate. C) reabsorbs the choline. D) reabsorbs axoplasm. E) pinches off and a new terminal grows.
c
Branches that may occur along an axon are called A) telodendria. B) synaptic terminals. C) collaterals. D) hillocks. E) synapses
c
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
In a(n) ________ neuron, the dendrites and axon are continuous or fused. A) multipolar B) anaxonic C) unipolar D) bipolar E) interneuron
c
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
Ion channels that are always open are called ________ channels. A) active B) gated C) leak D) regulated E) local
c
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
Neurotransmitters ready for release are stored in synaptic A) telodendria. B) terminals. C) vesicles. D) mitochondria. E) neurosomes.
c
The ________ nervous system is composed of the brain and spinal cord. A) autonomic B) peripheral C) central D) efferent E) afferent
c
The ion that triggers the release of acetylcholine into the synaptic cleft is A) sodium. B) potassium. C) calcium. D) chloride. E) magnesium.
c
The most abundant class of neuron in the central nervous system is A) anaxonic. B) bipolar. C) multipolar. D) pseudopolar. E) unipolar.
c
The myelin sheath that covers many CNS axons is formed by A) astrocytes. B) satellite cells. C) oligodendrocytes. D) microglia. E) ependymal cells.
c
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
________ account for roughly half of the volume of the nervous system. A) Axons B) Dendrites C) Neuroglia D) Synapses E) Efferent fibers
c
________ 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
Most neurons lack ________ and so are permanently blocked from undergoing cell division.
centrioles
A movement of charges in response to a potential difference is called a ________.
current
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
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
Cholinergic synapses release the neurotransmitter A) norepinephrine. B) adrenalin. C) serotonin. D) acetylcholine. E) GABA.
d
Clusters of RER and free ribosomes in neurons are called A) neurofilaments. B) neurofibrils. C) perikaryon. D) Nissl bodies. E) microglia.
d
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
EPSPs (excitatory postsynaptic potentials) occur when A) more potassium ions than usual leak out of a cell. B) more calcium ions than usual leak out of a cell. C) chloride ions enter a cell. D) extra sodium ions enter a cell. E) hyperpolarizations occur.
d
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
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
Presynaptic facilitation by serotonin is caused by A) increased extracellular concentration of sodium ion. B) increased extracellular concentration of potassium ion. C) blockage of calcium channels in the presynaptic membrane. D) calcium channels in the presynaptic membrane remaining open longer. E) temporal summation.
d
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
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
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
Which of the following is not a recognized structural classification for neurons? A) anaxonic B) bipolar C) multipolar D) pseudopolar E) unipolar
d
________ 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
________ 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
The sensory loss and muscle weakness associated with multiple sclerosis are a consequence of ________.
demyelination
A shift of the resting transmembrane potential toward 0 mV is called ________.
depolarization
A neuron that receives neurotransmitter from another neuron is called A) the presynaptic neuron. B) the motor neuron. C) an oligodendrocyte. D) an interneuron. E) the postsynaptic neuron.
e
A stimulus that changes a postsynaptic neuron's membrane from resting potential to -85 mV is: A) an excitatory stimulus B) a depolarizing stimulus C) a temporal stimulus D) a saltatory stimulus E) an inhibitory stimulus
e
Active neurons need ATP to support which of the following? A) the movement of materials to the soma by axoplasmic transport B) the synthesis of neurotransmitter molecules C) the movement of materials from the soma by axoplasmic transport D) the recovery from action potentials E) All of the answers are correct.
e
Any stimulus that opens ________ ion channel will produce a graded potential. A) a voltage-gated B) a chemically-gated C) a sodium D) a mechanically-gated E) All of the answers are correct.
e
Each of the following is an example of a neuroeffector junction, 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
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
How would a chemical that prevents the opening of voltage-regulated Na+ channels affect the function of a neuron? A) neuron will only be able to hyperpolarize B) neuron will depolarize more rapidly C) action potentials will lack a repolarization phase D) neuron will automatically and repeatedly produce graded potentials E) neuron will only be capable of producing graded potentials
e
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
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
Neurons that have several dendrites and a single axon are called A) anaxonic. B) unipolar. C) bipolar. D) tripolar. E) multipolar.
e
Raising the potassium ion concentration in the extracellular fluid surrounding a nerve cell will have which 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
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
The cytoplasm that surrounds the nucleus of a neuron is called the A) protoplasm. B) nucleoplasm. C) sarcoplasm. D) neuroplasm. E) perikaryon.
e
The effect that a neurotransmitter has on the postsynaptic membrane depends on A) the frequency of neurotransmitter release. B) the nature of the neurotransmitter. C) the characteristics of the receptors. D) the quantity of neurotransmitters released. E) All of the answers are correct.
e
The efferent division of the peripheral nervous system innervates: A) skeletal muscle cells B) smooth muscle cells C) heart muscle cells D) glandular cells E) All of the answers are correct.
e
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
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
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
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
When pressure is applied to neural tissue, all these effects are possible, except A) a decrease in blood flow. B) a decrease in available oxygen. C) action potentials are generated spontaneously. D) glial cells degenerate. E) neurons are triggered to divide.
e
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
Which of the following is a recognized class of opioid neuromodulators? A) endorphins B) enkephalins C) endomorphins D) dynorphins E) All of the answers are correct.
e
Which of the following is not a possible drug effect on synaptic function? A) interfere with neurotransmitter synthesis B) interfere with neurotransmitter reuptake C) prevent neurotransmitter inactivation D) block neurotransmitter binding to receptors E) change the type of receptor found in the postsynaptic membrane
e
________ 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
Neuron cell bodies in the PNS are clustered together in masses called ________.
ganglia
Regions of the CNS where neuron cell bodies dominate constitute the ________ matter.
gray
The presence of ________ dramatically increases the speed at which an action potential moves along an axon.
myelin
Compounds that alter the rate of neurotransmitter release by the presynaptic neuron or change the postsynaptic cell's response to neurotransmitters are called ________.
neuromodulators
The nervous tissue outside of the central nervous system composes the ________ nervous system.
peripheral
The separation of positive and negative charges across the membrane creates a ________ difference, or voltage.
potential
The period during which an excitable membrane can respond again, but only if the stimulus is greater than the threshold stimulus, is the ________.
relative refractory period
A change in the conditions in the synaptic terminal can influence the soma as a result of ________ axoplasmic transport.
retrograde
