HCS 215 Chapter 7 Test Bank

1) The central nervous system, which is composed of the brain and spinal cord, receives and processes information from both the external environment, known as ________ information and, the internal environment, which refers to ________ information.

A) special : somatic

B) peripheral : somatic

C) somatic : autonomic

D) somatic : visceral

E) sensory : visceral

E

2) In the peripheral nervous system, ________ neurons carry sensory and visceral information to the central nervous system, and ________ neurons leave the central nervous system and innervate organs, which are usually muscles or glands.

A) sensory : somatic

B) somatic : sensory

C) efferent : afferent

D) afferent : efferent

E) sympathetic : parasympathetic

D

3) Which of the following accurately describes afferent neurons?

A) The cell body is located in the ventral horn of the spinal cord.

B) They transmit information from the CNS to the periphery.

C) They transmit information from the periphery to the CNS.

D) They are the most abundant class of neurons.

E) They are typically multipolar neurons.

C

4) What two divisions of the autonomic nervous system have opposite effects on the organs they innervate?

A) somatic and motor

B) parasympathetic and sympathetic

C) peripheral and central

D) somatic and enteric

E) afferent and efferent

B

5) What is the functional unit of the nervous system?

A) axons

B) neurons

C) the brain

D) the central nervous system

E) glial cells

B

6) On what portion of the neuron do action potentials propagate?

A) soma

B) cell body

C) nucleus

D) axon

E) dendrite

D

7) ________ branch from the cell body and receive input from other neurons at specialized junctions called ________.

A) Somas : synapses

B) Dendrites : cell bodies

C) Dendrites : axon terminals

D) Dendrites : synapses

E) Axon hillocks : axon terminals

D

8) An action potential originates at the ________ and travels along the axon until it reaches the ________.

A) axon terminal : axon hillock

B) dendrite : axon terminal

C) axon hillock : dendrite

D) dendrite : axon hillock

E) axon hillock : axon terminal

E

9) The movement of synaptic vesicles to the end of the axon terminal involves what type of transport?

A) anterograde

B) retrograde

C) receptor-mediated

D) passive

E) pinocytosis

A

10) What type of ion channels in the membrane of neurons allows ions to move across the membrane at rest and thereby contribute to resting membrane potential?

A) voltage-gated channels

B) resting channels

C) potential-gated channels

D) leak channels

E) ligand-gated channels

D

11) What type of ion channels in the membrane of neurons open or close in response to a neurotransmitter binding to its receptor?

A) voltage-gated channels

B) synaptic channels

C) potential-gated channels

D) leak channels

E) ligand-gated channels

E

12) In a neuron, where is the greatest concentration of voltage-gated sodium and voltage-gated potassium channels?

A) dendrites

B) soma

C) axon hillock

D) axon

E) axon terminal

C

13) In a neuron, where are voltage-gated calcium channels located?

A) dendrites

B) soma

C) axon hillock

D) axon

E) axon terminal

E

14) What is the structural classification of a neuron composed of a single axon and a number of dendritic projections from the nerve cell body?

A) multipolar

B) bipolar

C) pseudo-unipolar

D) unipolar

E) polar

A

15) A group of nerve cell bodies in the peripheral nervous system are referred to as

A) ganglia.

B) pathways.

C) tracts.

D) nuclei.

E) commissures.

A

16) What functional class of neurons accounts for 99 percent of the neurons in the body processing sensory information and carrying out complex functions?

A) afferent

B) efferent

C) interneurons

D) visceral

E) bipolar

C

17) What type of cell enhances the velocity of electrical transmission of an action potential along an axon in the central nervous system?

A) oligodendrocyte

B) Schwann cell

C) astrocyte

D) ependymal cell

E) microglia

A

18) Which of the following best describes the function of the myelin sheath?

A) decrease ion permeability in the nodes of Ranvier

B) increase leakage of ions across the membrane

C) decrease axonal conduction velocity

D) increase a membrane's ion permeability

E) reduce a membrane's ion permeability

E

19) Most neurons have a resting membrane potential of

A) -5 mV.

B) -55 mV.

C) -70 mV.

D) +30 mV.

E) +100 mV.

C

20) Which of the following is the correct term for the movement of an electrical charge across a membrane?

A) resistance

B) current

C) potential difference

D) transistor

E) capacitance

B

21) Which of the following determines the resistance to an ion's movement across a membrane?

A) enzymes on the surface of the cell membrane

B) ion channels within the membrane

C) receptors on the cell membrane

D) the ions present on either side of the membrane

E) the resting membrane potential

B

22) What is the inverse of resistance?

A) voltage

B) current

C) conductance

D) impedance

E) flux

C

23) Which of the following best describes the electrochemical forces acting on sodium and potassium ions at the resting membrane potential?

A) Forces on both sodium and potassium ions are to move into the cell.

B) Forces on both sodium and potassium ions are to move out of the cell.

C) The force on sodium ions is to move into the cell, and the force on potassium ions is to move out of the cell.

D) The force on sodium ions is to move out of the cell, and the force on potassium ions is to move into the cell.

E) There is no force on either ion to move.

C

24) At the resting membrane potential, the membrane is most permeable to ________, which moves ________ the cell due to its electrochemical gradient.

A) sodium : into

B) potassium : into

C) potassium : out of

D) sodium : out of

E) chloride : into

C

25) At the resting membrane potential, the electrochemical gradient for sodium across the membrane is such that the net flux for sodium movement is directed ________, thereby causing the cell's membrane potential to become more ________.

A) inward : positive

B) inward : negative

C) outward : positive

D) outward : negative

E) at equilibrium : positive

A

26) The ________ maintains the resting membrane potential.

A) Na+/K+ pump

B) action potential

C) equilibrium potential

D) Na+/Ca2+ exchanger

E) Na+/H+ antiporter

A

27) What equation is used to calculate the membrane potential based on ion concentration gradients and permeabilities?

A) GHK equation

B) NAD equation

C) Nernst equation

D) Fick's equation

E) None of the answers is correct.

A

28) The fact that a cell has an electrical potential difference across its membrane makes that cell

A) depolarized.

B) hyperpolarized.

C) repolarized.

D) polarized.

E) polar.

D

29) A change in a cell's membrane potential, such that the inside of the cell becomes more positive, is referred to as a ________ whereas if it becomes more negative it is referred to as ________.

A) depolarization : hyperpolarization

B) hyperpolarization : depolarization

C) hypopolarization : repolarization

D) polarization : depolarization

E) repolarization : resting membrane potential

A

30) Saxitoxin (STX) is the most well-known paralytic shellfish toxin caused by the phenomenon known as "red tide." Which statement below best describes why this neurotoxin causes paralysis?

A) It acts on the hypothalamus of the brain, shutting down all neurological functions.

B) It acts on the potassium channels within a neuron, hyperpolarizing the cell membrane; therefore, no action potential can be generated.

C) It acts by blocking voltage-gated sodium channels which are needed to generate an action potential.

D) It blocks ligand-gated channels on the postsynaptic membrane, which blocks signals leaving the central nervous system.

E) It prevents the synaptic vesicles from migrating to the axon terminal; therefore, no action potentials are generated.

C

31) What determines the strength of a graded potential?

A) the size of the stimulus

B) the amount of cytoplasmic resistance within the soma of the neuron

C) the amount of leak channels open in the neuron

D) the amount of voltage-gated channels in the neuron

E) the diameter of the axon

A

32) A(n) ________ is a subthreshold change in membrane potential within the cell body that decays as it travels away from its point of origin.

A) polarization

B) hyperpolarization

C) depolarization

D) action potential

E) graded potential

E

33) The direction of change in membrane potential, in response to a stimulus that initiates a graded potential, is dependent upon

A) that membrane's threshold potential.

B) the gating of potassium channels only.

C) the gating of sodium channels only.

D) the changes in ion concentration across the membrane.

E) the ion channels that are opened or closed.

E

34) Which statement best describes how graded potentials determine whether an action potential will be generated or not?

A) when an excitatory depolarization reaches threshold

B) when sodium enters the soma of a cell

C) when the neuron is hyperpolarized

D) when electrotonic conduction occurs within the soma of the neuron

E) when the axon hillock is repolarized

A

35) If the soma of a neuron became more permeable to potassium, which statement below best describes the graded potential that would be generated in the soma?

A) Potassium is a cation; therefore, it would cause an excitatory depolarization.

B) Potassium would leave the cell, causing the membrane to hyperpolarize.

C) Potassium would enter the cell, causing the membrane to depolarize and reach threshold.

D) Potassium would reach its equilibrium potential and the voltage inside the cell would not change.

E) Potassium is an inhibitory second messenger; therefore, it would cause amplification of the graded potential.

B

36) When a weak stimulus is applied in rapid succession, it will often reach threshold due to

A) temporal summation.

B) spatial summation.

C) excitatory summation.

D) inhibitory summation.

E) voltage potential.

A

37) Which of the following is an example of spatial summation?

A) Two stimuli from two sources produce graded potentials on the same neuron at the same time such that the two potentials sum.

B) Two rapid stimuli from the same source produce graded potentials on the neurons that sum.

C) An action potential occurs at the same time as a graded potential, and they sum.

D) A neuron sends out information through collaterals to several target cells.

E) Two action potentials occur at the same time and sum.

A

38) Which of the following changes in membrane potential is considered excitatory?

A) hyperpolarization only

B) depolarization only

C) repolarization only

D) both hyperpolarization and depolarization

E) both hyperpolarization and repolarization

B

39) If the graded potential remains above threshold once it reaches the ________, an action potential will be generated.

A) cell body

B) dendrite

C) axon

D) axon hillock

E) nucleus

D

40) The opening of sodium channels causes a rapid ________ of sodium that ________ the neuron's membrane.

A) efflux : hyperpolarizes

B) influx : hyperpolarizes

C) efflux : depolarizes

D) influx : depolarizes

E) influx : repolarizes

D

41) The depolarization phase of the action potential is generated by a rapid

A) opening of sodium channels.

B) closure of potassium channels.

C) closure of sodium channels.

D) opening of potassium channels.

E) opening of chloride channels.

A

42) The repolarization phase of the action potential in a neuron is driven by the

A) closure of potassium channels.

B) opening of calcium channels.

C) opening of sodium channels.

D) opening of sodium channels and closure of potassium channels.

E) closure of sodium channels and opening of potassium channels.

E

43) The repolarization phase of action potentials in neurons is due primarily to

A) increased activity of the Na+/K+pump.

B) sodium flow out of the cell.

C) sodium flow into the cell.

D) potassium flow into the cell.

E) potassium flow out of the cell.

E

44) In myelinated axons, sodium and potassium channels would be concentrated in what area?

A) axon hillock

B) axon terminal

C) nodes of Ranvier

D) dendrites

E) nucleus

C

45) The depolarization of the membrane due to a stimulus is a regenerative mechanism meaning that, once sodium gates begin to open, even more sodium gates will be activated leading to a larger inflow of sodium ions and more depolarization until it is terminated when sodium gates close. This is an example of

A) negative feedback.

B) positive feedback.

C) excitatory graded potentials.

D) inhibitory graded potentials.

E) electrotonic conduction.

B

46) A subthreshold stimulus will not generate an action potential whereas a suprathreshold stimulus does generate an action potential. This is an example of

A) negative feedback.

B) positive feedback.

C) the all-or-none principle.

D) a refractory period.

E) electrotonic conduction.

C

47) The magnitude of depolarization at the peak of an action potential is dependent on what factor?

A) the size of the stimulus

B) the size of the graded potential

C) the strength of the electrochemical gradient for sodium and potassium ions relative to their permeability to these ions

D) the concentration of sodium and potassium ions

E) the length of the refractory period

C

48) In order to generate an action potential, the magnitude of the inward sodium current must be large enough to overcome which of the following?

A) outward potassium current

B) inward potassium current

C) outward sodium current

D) inward chloride current

E) outward calcium current

A

49) During which of the following states are the majority of voltage-gated sodium channels closed and incapable of opening?

A) at the resting membrane potential

B) during depolarization

C) during the absolute refractory period

D) during the relative refractory period

E) during the after-hyperpolarization

C

50) The all-or-none principle, associated with the action potential, states that

A) the positive feedback loop for the sodium channel is terminated by the inactivation gate.

B) there is a positive feedback loop for sodium channels that results in a rapid membrane depolarization.

C) all of the action potentials will be generated from the axon hillock.

D) once membrane potential reaches threshold, an action potential will be generated and that action potential will always be the same magnitude.

E) following an action potential, the membrane will be repolarized by the opening of a potassium channel.

D

51) Toward the end of the relative refractory period, the continued decrease in stimulus intensity required to initiate an action potential is caused by

A) decreased sodium permeability.

B) increased potassium permeability.

C) closure of the sodium activation gate.

D) decreased potassium permeability.

E) the number of sodium channels whose inactivation gate has not opened.

D

52) Which statement below best describes why action potentials travel in only one direction?

A) The all-or-none principle explains this.

B) They have a refractory period.

C) The diameter of the axon explains this.

D) Only sodium- and potassium-gated channels are found on the axon.

E) They have myelinated axons.

B

53) How can action potentials relay information about the intensity of a stimulus, such as distinguishing between a loud and soft sound?

A) due to the frequency of action potentials

B) due to the magnitude of action potentials

C) due to summation of several action potentials

D) due to electrotonic conduction

E) due to the decremental properties of graded potentials

A

54) What limits the maximum number of action potentials on an axon?

A) the concentration of sodium within the cytoplasm of the cell

B) the absolute refractory period

C) the relative refractory period

D) whether the axon is myelinated or not

E) the diameter of the axon

B

55) For an unmyelinated axon, conduction velocity is primarily determined by the

A) type of potassium channel activated.

B) type of sodium channel activated.

C) diameter of the axon.

D) permeability of the axonal membrane.

E) number of ion channels present on the membrane.

C

56) As an action potential is propagated away from the axon hillock, why does propagation continue in one direction?

A) The region just behind the action potential is in the absolute refractory period.

B) The region just in front of the action potential is in the absolute refractory period.

C) The region just behind the action potential is in the relative refractory period.

D) The region just in front of the action potential is in the relative refractory period.

E) They will travel the path of least resistance.

A

57) ________ is the mechanism by which action potentials are propagated in unmyelinated axons.

A) The all-or-none principle

B) The regenerative mechanism

C) After-hyperpolarization

D) Temporal summation

E) Electrotonic conduction

E

58) In myelinated nerve fibers, where do action potentials occur?

A) cell body

B) nodes of Ranvier

C) Schwann cell

D) underlying myelin sheath

E) oligodendrocyte

B

59) The jumping of an action potential from node-to-node is called

A) nodal conduction.

B) propagation.

C) electrotonic conduction.

D) saltatory conduction.

E) nodal propagation.

D

60) Which of the following axons would have the fastest conduction velocity?

A) diameter = 5 microns, myelinated

B) diameter = 5 microns, unmyelinated

C) diameter = 20 microns, myelinated

D) diameter = 20 microns, unmyelinated

E) diameter = 1 micron, myelinated

C

61) Which statement best describes how local anesthetics such as Novocaine work in numbing neurons?

A) by blocking voltage-gated sodium channels

B) by blocking voltage-gated potassium channels

C) by making the cell membrane more permeable to potassium

D) by making the cell membrane more permeable to sodium

E) by binding to the enzyme sodiumase

A

62) Which of the following are common symptoms of peripheral neuropathy?

A) numbness, tingling sensation, or pain in the hands and feet

B) dizziness, diarrhea, indigestion and impotence

C) confusion, excessive thirst, dehydration, and frequent urination

D) numbness of the tongue, jaw, and ears

E) increased heart rate, excessive sweating, and red skin

A

63) What percentage of people with diabetes develop peripheral neuropathy?

A) 5 percent

B) 10 percent

C) 20 percent

D) 30 percent

E) 50 percent

D

64) Why do the distributions of sodium and potassium ions across the plasma membrane of neurons not change appreciably, even following hundreds of action potentials?

A) The movement of sodium and potassium ions that occurs during an action potential is countered by the passive leak of these ions when a neuron is at rest.

B) The movement of sodium and potassium ions that occurs during an action potential is countered by the active transport of these ions by the Na+/K+ pump.

C) The movement of sodium and potassium ions that occurs during an action potential is countered by the passive movement of these ions during the repolarization phase.

D) The movement of sodium and potassium ions that occurs during an action potential is countered by the passive movement of these ions during the after-hyperpolarization.

E) The movement of sodium and potassium ions that occurs during an action potential is countered by counter-tran

B

65) What portion of the peripheral nervous system communicates to effector organs?

A) afferent nervous system

B) efferent nervous system

C) enteric nervous system

D) central nervous system

E) spinothalmic tract

B

66) What portion of the peripheral nervous system transmits information from sensory receptors to the central nervous system?

A) afferent nervous system

B) efferent nervous system

C) somatic nervous system

D) central nervous system

E) autonomic nervous system

A

67) What portion of the efferent branch of the nervous system communicates to glands and cardiac muscle?

A) afferent nervous system

B) enteric nervous system

C) somatic nervous system

D) central nervous system

E) autonomic nervous system

E

68) The brain and spinal cord are part of which of the following branches of the nervous system?

A) afferent nervous system

B) efferent nervous system

C) somatic nervous system

D) central nervous system

E) enteric nervous system

D

69) What portion of the efferent nervous system communicates with skeletal muscle?

A) afferent nervous system

B) enteric nervous system

C) somatic nervous system

D) central nervous system

E) autonomic nervous system

C

70) What portion of the nervous system provides communication between peripheral organs and the brain and spinal cord?

A) afferent nervous system

B) efferent nervous system

C) somatic nervous system

D) central nervous system

E) peripheral nervous system

E

71) What nervous system is found in the intestinal tract?

A) afferent nervous system

B) efferent nervous system

C) somatic nervous system

D) central nervous system

E) enteric nervous system

E

72) Which of the following potentials can sum?

A) graded potentials

B) threshold potentials

C) action potentials

D) both graded potentials and action potentials

E) neither graded potentials nor action potentials

A

73) Which of the following potentials are affected by refractory periods?

A) graded potentials

B) threshold potentials

C) action potentials

D) both graded potentials and action potentials

E) neither graded potentials nor action potentials

C

74) Which of the following potentials is a result of opening or closing of ion channels?

A) graded potentials

B) threshold potentials

C) action potentials

D) both graded potentials and action potentials

E) neither graded potentials nor action potentials

D

75) Which of the following potentials dissipate in size as the potential moves away from the site of initiation?

A) graded potentials

B) threshold potentials

C) action potentials

D) both graded potentials and action potentials

E) neither graded potentials nor action potentials

A

76) Which of the following potentials has an all-or-none response?

A) graded potentials

B) threshold potentials

C) action potentials

D) both graded potentials and action potentials

E) neither graded potentials nor action potentials

C

77) Which of the following potentials can reach or exceed the sodium equilibrium potential?

A) graded potentials

B) threshold potentials

C) action potentials

D) both graded potentials and action potentials

E) neither graded potentials nor action potentials

E

85) Information gathered about our internal environment (i.e., fullness of the stomach, blood pressure, etc.) is called ________ information.

A) efferent

B) somatic

C) visceral

D) sensory

E) afferent

C

86) What is the most common neuronal cell type?

A) afferent neuron

B) pseudo-unipolar neuron

C) bipolar neuron

D) interneuron

E) efferent neuron

D

87) What is the only glial cell found outside of the central nervous system?

A) ependymal cells

B) oligodendrocytes

C) Schwann cell

D) microglia

E) astrocytes

C

88) Which type of glial cell provides the myelin sheath for many axons in the central nervous system?

A) Schwann cell

B) oligodendrocytes

C) astrocytes

D) ependymal cells

E) microglia

B

89) Once a membrane potential has been developed, the force that drives a particular ion across the membrane is its

A) concentration gradient.

B) electrochemical gradient.

C) chemical gradient.

D) electrical gradient.

E) electrogenic pump.

B

90) What is the passive spread of current along a membrane called?

A) action potential

B) electrotonic conduction

C) graded potential

D) refractory period

E) resistance

B

91) The fact that the opening of some sodium channels can induce several other sodium channels to open describes the ________ property of these channels.

A) ligand

B) regenerative

C) suprathreshold

D) refractory

E) all-or-none principle

B

92) What is the level of membrane depolarization required to induce the sodium channel's positive feedback loop called?

A) axon terminal

B) axon hillock

C) suprathreshold

D) subthreshold

E) threshold

E

93) What type of ion channels is located along the axon?

A) mechanical channels

B) initiation channels

C) ligand-gated channels

D) propagation channels

E) voltage-gated channels

E

94) In the peripheral nervous system, myelin is formed by ________. In the central nervous system, myelin is formed by ________.

A) oligodendrocytes : Schwann cells

B) Schwann cells : astrocytes

C) Schwann cells : microglial cells

D) Schwann cells : oligodendrocytes

D

95) At rest, the plasma membrane is more permeable to which of the following ions?

A) sodium (Na+)

B) potassium (K+)

C) chloride (Cl-)

D) calcium (Ca++)

E) phosphate (PO4-)

B

96) The resting membrane potential is close to the equilibrium potential of which of the following ions?

A) sodium (Na+)

B) potassium (K+)

C) chloride (Cl-)

D) calcium (Ca++)

E) phosphate (PO4-)

B

97) During the rapid depolarization phase of an action potential, the plasma membrane is more permeable to which of the following ions?

A) sodium (Na+)

B) potassium (K+)

C) chloride (Cl-)

D) calcium (Ca++)

E) phosphate (PO4-)

A

98) Increased permeability to what ion is responsible for the relative refractory period?

A) sodium (Na+)

B) potassium (K+)

C) chloride (Cl-)

D) calcium (Ca++)

E) phosphate (PO4-)

B