CH. 12 HW A&P 223

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) unipolar.

Summation that results from the cumulative effect of multiple synapses at multiple places on the neuron is designated: a) hyperpolarization. b) temporal summation. c) spatial summation. d) impulse transmission. e) inhibition of the impulse.

c) spatial summation.

The neurilemma of axons in the peripheral nervous system is formed by: a) astrocytes. b) Schwann cells. c) satellite cells. d) microglia. e) oligodendrocytes.

b) Schwann cells.

The period during which an excitable membrane cannot respond to further stimulation is the ________ period. a) absolute refractory. b) relative refractory. c) lag. d) stationary. e) resting.

a) absolute refractory.

Cholinergic synapses release the neurotransmitter: a) acetylcholine. b) adrenalin. c) serotonin. d) GABA. e) norepinephrine.

a) acetylcholine.

The ________ division of the peripheral nervous system brings sensory information to the central nervous system. a) afferent. b) parasympathetic. c) peripheral. d) autonomic. e) somatic.

a) afferent.

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) anaxonic.

The ________ nervous system provides involuntary regulation of smooth muscle, cardiac muscle, and glandular activity. a) autonomic. b) peripheral. c) motor. d) somatic. e) afferent.

a) autonomic.

Which of the following is the primary second messenger in G-protein coupled post-synaptic cells? a) cAMP. b) ATP. c) GABA. d) CO. e) NO.

a) cAMP.

If acetylcholine (ACh) causes inhibition of a postsynaptic neuron, to what type of membrane channel did the ACh bind? a) chemically-regulated potassium channel. b) chemically-regulated sodium channel. c) mechanically-regulated channel. d) voltage-regulated calcium channel. e) voltage-regulated sodium channels.

a) chemically-regulated potassium channel.

________ nerves are nerves that connect to the brain. a) cranial. b) interneural. c) myelinated. d) unmyelinated. e) spinal.

a) cranial.

A movement of charges in response to a potential difference is called: a) current. b) electricity. c) action potential. d) hyperpolarization. e) depolarization.

a) current.

Voltage-gated channels are present: a) in the membrane that covers axons. b) on the surface of dendrites. c) along the perikaryon of neurons. d) on the soma of neurons. e) at the motor end plate.

a) in the membrane that covers axons.

The basic functional unit of the nervous system is the: a) neuron. b) axon. c) glial cell. d) receptor. e) nerve.

a) neuron.

The nervous tissue outside of the central nervous system composes the ________ nervous system. a) peripheral. b) somatic. c) autonomic. d) parasympathetic. e) afferent.

a) peripheral.

The period during which an excitable membrane can respond again, but only if the stimulus is greater than the threshold stimulus, is the ________ period. a) relative refractory. b) absolute refractory. c) stationary. d) resting. e) lag.

a) relative refractory.

The ________ nervous system controls the skeletal muscles. a) somatic. b) autonomic. c) sympathetic. d) afferent. e) parasympathetic.

a) somatic.

Which of the following is not a function of astrocytes? a) they rebuild injured neurons. b) they create three dimensional framework for the CNS. c) they adjust the composition of the interstitial tissue. d) they maintain the blood-brain barrier. e) they guide neuron development.

a) they rebuild injured neurons.

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) 6,7,4,1,2,3,5. b) 4,6,7,1,2,3,5. c) 4,6,7,3,2,5,1. d) 4,2,5,6,7,3,1. e) 2,4,6,7,1,3,5.

b) 4,6,7,1,2,3,5.

In which of the following would the rate of impulse conduction be the greatest? a) a myelinated fiber of 1-um diameter. b) a myelinated fiber of 10-um diameter. c) an unmyelinated fiber of 10-um diameter. d) an unmyelinated fiber of 20-um diameter. e) it would be the same in all because of the all-or-none principle.

b) a myelinated fiber of 10-um diameter.

The ________ principle states that the size and speed of the action potential are independent of the stimulus strength. a) summation. b) all-or-none. c) potential. d) polarization. e) threshold.

b) all-or-none.

The neuroglial cells that participate in maintaining the blood-brain barrier are the: a) oligodendrocytes. b) astrocytes. c) Schwann cells. d) microglia. e) ependymal cells.

b) astrocytes.

The ________ nervous system is composed of the brain and spinal cord. a) afferent. b) central. c) efferent. d) peripheral. e) autonomic.

b) central.

At a(n) ________ synapse, a neurotransmitter is released to stimulate the postsynaptic membrane. a) cell. b) chemical. c) electrical d) osmotic. e) gap.

b) chemical.

Functions of astrocytes include all of the following except: a) guiding neuron development. b) conducting action potentials. c) maintaining the blood-brain barrier. d) forming a three-dimensional framework for the CNS. e) responding to neural tissue damage.

b) conducting action potentials.

The ________ division of the nervous system carries motor commands to muscles and glands. a) peripheral. b) efferent. c) spinal. d) afferent. e) autonomic.

b) efferent.

________ line the brain ventricles and spinal canal. a) microglia. b) ependymal cells. c) oligodendrocytes. d) astrocytes. e) satellite cells.

b) ependymal cells.

The presence of ________ dramatically increases the speed at which an action potential moves along an axon. a) a capsule. b) myelin. c) neurilemma. d) plasma protein. e) glial cells.

b) myelin.

Which neuroglia myelinate CNS axons and which neuroglia myelinate PNS axons? a) astrocytes; satellite cells. b) oligodendrocytes.; Schwann cells. c) astrocytes; Schwann cells. d) Schwann cells; oligodendrocytes. e) satellite cells; astrocytes.

b) oligodendrocytes; Schwann cells.

Which of the following is the primary second messenger in G-protein coupled post-synaptic cells? a) cranial. b) spinal. c) autonomic. d) multipolar. e) afferent.

b) spinal.

The site of intercellular communication between a neuron and another cell is the: a) collateral. b) synapse. c) hillock. d) axolemma. e) telodendria.

b) synapse.

If the chemically gated sodium channels in the postsynaptic membrane were completely blocked, a) the presynaptic membrane would be unable to reach threshold. b) synaptic transmission would fail. c) the presynaptic neuron would release a different neurotransmitter. d) release of neurotransmitter would stop. e) smaller action potentials would result.

b) synaptic transmission would fail.

Axons terminate in a series of fine extensions known as: a) synapses. b) telodendria. c) collaterals. d) dendrites. e) terminals.

b) telodendria.

Below are the events that occur during continuous propagation of action potential. Select the correct order in which the events occur. 1. Adjacent membrane segment depolarizes. 2. Local current spreads to adjacent voltage gated channel. 3. Threshold is met. 4. Local current develops due to sodium moving in the cytosol. a) 1,4,2,3. b) 4,2,1,3. c) 4,2,3,1. d) 2,4,1,3. e) 2,4,3,1.

c) 4,2,3,1.

The part of the peripheral nervous system that carries sensory information to the CNS is designated a) somatic. b) efferent. c) afferent. d) autonomic. e) motor.

c) afferent.

The plasma membrane of an axon is called the: a) axon terminal. b) myelin sheath. c) axolemma. d) sarcolemma. e) neurilemma.

c) axolemma.

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) bipolar.

A postsynaptic neuron will have an excitatory postsynaptic potential (EPSP) when: a) more calcium ions than usual diffuse into the neuron. b) chemically regulated potassium channels are open and potassium is diffusing into the cell. c) chemically regulated sodium channels are open and sodium is diffusing into the cell. d) more potassium ions than usual diffuse out of the neuron. e) the neuron is hyperpolarized.

c) chemically regulated sodium channels are open and sodium is diffusing into the cell.

A threshold stimulus is the: a) electrical current that crosses the synaptic cleft. b) hyperpolarization of an axon. c) depolarization necessary to cause an action potential. d) peak of an action potential. e) resting membrane potential.

c) depolarization necessary to cause an action potential.

Opening of sodium channels in the axon membrane causes: a) repolarization. b) hyperpolarization. c) depolarization. d) inhibition. e) increased negative charge inside the membrane.

c) depolarization.

________ carry motor information to peripheral effectors. a) interneurons. b) afferent neurons. c) efferent neurons. d) multipolar neurons. e) unipolar neurons.

c) efferent neurons.

Damage to ependymal cells would most likely affect the: a) transport f neurotransmitters within axons. b) formation of myelin sheaths. c) formation of cerebrospinal fluid. d) formation of ganglia. e) repair of axons.

c) formation of cerebrospinal fluid.

In the peripheral nervous system, Schwann cells participate in the repair of damaged nerves by: a) producing more satellite cells that fuse to form new axons. b) producing new axons. c) forming a cellular cord that directs axonal regrowth. d) regenerating cell bodies for the neurons. e) clearing away cellular debris.

c) forming a cellular cord that directs axonal regrowth.

Voltage-gated sodium channels have both an activation gate and a(n) ________ gate. a) threshold. b) ion. c) inactivation. d) swinging. e) repolarization.

c) inactivation.

Which of the following is not a function of the neuroglia? a) maintenance of blood-brain barrier. b) phagocytosis. c) memory. d) secretion of cerebrospinal fluid. e) support.

c) memory.

Small, wandering cells that engulf cell debris and pathogens in the CNS are called: a) oligodendrocytes. b) satellite cells. c) microglia. d) ependymal cells. e) astrocytes.

c) microglia.

Which neurotransmitter has widespread effects on a person's attention and emotional state? a) dopamine. b) norepinephrine. c) serotonin. d) GABA. e) endorphins.

c) serotonin.

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) the absolute refractory period would be shorter than normal. c) the axon would be unable to generate action potentials. d) action potentials would lack a repolarization phase. e) none, because the chemically gated sodium channels would still function.

c) the axon would be unable to generate action potentials.

How would a chemical that prevents the opening of voltage-regulated Na+ channels affect the function of a neuron? a) the neuron will automatically and repeatedly produce graded potentials. b) the neuron will depolarize more rapidly. c) the neuron will only be capable of producing graded potentials. d) the neuron will only be able to hyperpolarize. e) action potentials will lack a repolarization phase.

c) the neuron will only be capable of producing graded potentials.

A neuron that receives neurotransmitter from another neuron is called a) a satellite cell. b) the motor neuron. c) the postsynaptic neuron. d) an oligodendrocyte. e) the presynaptic neuron.

c) the postsynaptic neuron.

The minimum stimulus required to trigger an action potential is known as the: a) incentive. b) all-or-none response c) threshold. d) potential. e) summation.

c) threshold.

Deteriorating changes in the distal segment of an axon as a result of a break between it and the soma is called ________ degeneration. a) peripheral. b) neural. c) central. d) Wallerian. e) conduction.

d) Wallerian.

The efferent division of the peripheral nervous system innervates ________ cells. a) smooth muscle. b) glandular. c) skeletal muscle. d) heart muscle. e) all of the answers are correct.

e) all of the answers are correct.

The all-or-none principle states that: a) only motor stimuli can activate action potentials. b) the greater the magnitude of the stimuli, the greater the magnitude of the action potential. c) all stimuli will produce identical action potentials. d) all stimuli great enough to bring the membrane to threshold will produce identical action potentials. e) only sensory stimuli can activate action potentials.

d) all stimuli great enough to bring the membrane to threshold will produce identical action potentials.

The largest and most numerous of the glial cells in the central nervous system are the: a) ependymal cells. b) satellite cells. c) microglia. d) astrocytes. e) oligodendrocytes.

d) astrocytes.

The ion that triggers the release of acetylcholine into the synaptic cleft is: a) magnesium. b) potassium. c) chloride. d) calcium. e) sodium.

d) calcium.

Which type of synapse is most common in the nervous system? a) electrical. b) radiative. c) mechanical. d) chemical. e) processing.

d) chemical.

A shift of the resting transmembrane potential toward 0 mV is called: a) repolarization. b) polarization. c) potential difference. d) depolarization. e) hyperpolarization.

d) depolarization.

________ channels open or close in response to physical distortion of the membrane surface. a) chemically gated. b) active. c) voltage-gated. d) mechanically gated. e) leak.

d) mechanically gated.

________ account for roughly half of the volume of the nervous system. a) efferent fibers. b) synapses. c) dendrites. d) neuroglia. e) axons.

d) neuroglia.

Which of the following neurotransmitters is a dissolved gas? a) aspartate. b) serotonin. c) glutamate. d) nitric oxide. e) histamine.

d) nitric oxide.

During repolarization of a neuron: a) potassium ions move into the cell. b) sodium ions move out of the cell. c) both sodium and potassium ions move into the cell. d) potassium ions move out of the cell. e) sodium ions move into the cell.

d) potassium ions move out of the cell.

Rapid impulse conduction from "node" to "node" is called: a) synaptic transmission. b) divergent propagation. c) spatial propagation. d) saltatory propagation. e) continuous propagation.

d) saltatory propagation.

Which of the following is a type of glial cell found in the peripheral nervous system? a) ependymal cells. b) oligodendrocytes. c) astrocytes. d) satellite cells. e) microglia.

d) satellite cells.

When cholinergic receptors are stimulated, a) chloride ions enter the postsynaptic neuron. b) chloride ions leave the postsynaptic neuron. c) sodium ions leave the postsynaptic neuron. d) sodium ions enter the postsynaptic neuron. e) norepinephrine deactivates acetylcholine.

d) sodium ions enter the postsynaptic neuron.

When a second EPSP (excitatory postsynaptic potential) arrives at a single synapse before the effects of the first have disappeared, what occurs? a) hyperpolarization. b) spatial summation. c) inhibition of the impulse. d) temporal summation. e) decrease in speed of impulse transmission.

d) temporal summation.

When potassium channels open and the ions diffuse through the membrane, a) the inside of the membrane will become more positive. b) the membrane will depolarize to threshold. c) there will be almost no effect on transmembrane potential. d) the inside of the membrane will become more negative. e) the membrane will become depolarized.

d) the inside of the membrane will become more negative.

Which of the following statements about the action potential is false? a) repolarization occurs as potassium ions leave the axon. b) during the repolarization phase, sodium channels close and potassium channels open. c) during depolarization phase, membrane potential becomes positive. d) the rapid depolarization phase is caused by the entry of potassium ions. e) during the hyperpolarization phase, the ion pumps re-establish the sodium and potassium concentrations across the cell membrane.

d) the rapid depolarization phase is caused by the entry of potassium channels.

Regions of the CNS with an abundance of myelinated axons constitute the ________ matter. a) neural. b) brain. c) ganglion. d) white. e) gray.

d) white.

At the normal resting membrane potential of a typical neuron, its sodium-potassium exchange pump transports: a) 1 intracellular sodium ion for 2 extracellular potassium ions. b) 3 extracellular sodium ions for 2 intracellular potassium ions. c) 2 intracellular sodium ions for 1 extracellular potassium ions. d) 3 intracellular sodium ions for 1 extracellular potassium ion. e) 3 intracellular sodium ions for 2 extracellular potassium ions.

e) 3 intracellular sodium ions for 2 extracellular potassium ions.

________ carry sensory information to the CNS. a) multipolar neurons. b) efferents neurons. c) motor neurons. d) interneurons. e) afferent neurons.

e) afferent neurons.

The effect that a neurotransmitter has on the postsynaptic membrane depends on the: a) quantity of neurotransmitters released. b) frequency of neurotransmitter release. c) characteristics of the receptors. d) nature of the neurotransmitter. e) all of the answers are correct.

e) all of the answers are correct.

IPSPs (inhibitory postsynaptic potentials): a) block the efflux of calcium ions. b) are local depolarizations. c) increase membrane permeability to sodium ions. d) block the efflux of potassium ions. e) are local hyperpolarizations

e) are local hyperpolarizations.

What triggers the release of acetylcholine from a synaptic terminal? a) release of calcium ions from the synaptic vesicles. b) synaptic vesicles fuse to dendrites. c) graded potentials in the synaptic terminal. d) diffusion of sodium ions out of the synaptic terminal. e) diffusion of calcium ions into the synaptic terminal.

e) diffusion of calcium ions into the synaptic terminal.

In a(n) ________ synapse, current flows directly between cells. a) chemical. b) gap. c) osmotic. d) cell. e) electrical.

e) electrical.

________ are the most numerous type of neuron in the CNS. a) motor neurons. b) unipolar neurons. c) sensory neurons. d) bipolar neurons. e) interneurons.

e) interneurons.

Which of the following is true about threshold for an action potential? a) voltage-gated potassium channels begin to open. b) the membrane begins to hyperpolarize. c) threshold for a typical neuron is approximately -30mV. d) voltage-gated potassium channels begin to close. e) it is more positive than the resting membrane potential.

e) it is more positive than the resting membrane potential.

Neurons that have several dendrites and a single axon are called: a) anaxonic. b) unipolar. c) bipolar. d) tripolar. e) multipolar.

e) multipolar.

The most abundant class of neuron in the central nervous system is: a) unipolar. b) bipolar. c) pseudopolar. d) anaxonic. e) multipolar.

e) multipolar.

The tiny gaps between adjacent Schwann cells are called: a) axolemma. b) vesicles. c) terminals. d) neurilemma. e) nodes of Ranvier.

e) nodes of Ranvier.

The myelin sheath that covers many CNS axons is formed by: a) astrocytes. b) microglia. c) satellite cells. d) ependymal cells. e) oligodendrocytes.

e) oligodendrocytes.

Sensory neurons of the PNS are: a) tripolar. b) multipolar. c) anaxonic. d) bipolar. e) unipolar.

e) unipolar.

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) 2,5,4,6,7,1,8,3. b) 6,4,2,7,1,8,3,5. c) 2,4,6,7,1,8,3,5. d) 4,2,6,7,8,5,3,1. e) 4,2,6,7,1,8,3,5.

e)4,2,6,7,1,8,3,5.