Chapter 4
Principles of Neural and Hormonal Communication
TEST QUESTIONS
Multiple Choice action potential.
1. A change in a membrane potential from +30
mV to –70 mV is an example of:
(a) depolarization.
(b) hyperpolarization.
(c) polarization.
(d) repolarization.
(e) zero potential.
ANSWER: d
2. The negative charge established along a nerve
cell membrane is due to:
(a) movement of Na+ into the cell.
(b) movement of proteins out of the cell.
(c) higher permeability of K+ relative to Na+.
(d) intracellular protein anions.
(e) both (c) and (d).
ANSWER: e
3. The cells of excitable and nonexcitable
tissues share which of the following
properties?
(a) a threshold potential.
(b) a resting membrane potential.
(c) an ability to open the Na+ gates.
(d) all of these answers.
(e) none of these answers.
ANSWER: b
4. Which term below best describes an excitable
when a resting membrane potential is
present?
(a) polarized.
(b) depolarized.
(c) hyperpolarized.
(d) repolarized.
(e) nonpolarized.
ANSWER: a
5. A threshold potential is:
(a) the potential achieved when two opposing
forces acting upon an ion (concentration and
electrical gradients) achieve a state of
equilibrium.
(b) the peak potential achieved during an
Page 1 of 24
, (c) the point at which there is an
explosive increase in Na+ permeability.
(d) the potential at which K+
permeability increases.
(e) always a positive potential.
ANSWER: c
6. A change in a membrane potential from –70
mV to –60mV is an example of:
(a) depolarization.
(b) hyperpolarization.
(c) polarization.
(d) repolarization.
(e) zero potential.
ANSWER: a
7. Graded potentials:
(a) are local changes in membrane potential
that occur in varying degrees of magnitude.
(b) serve as short-distance signals.
(c) serve as long-distance signals.
(d) both (a) and (b).
(e) both (a) and (c).
ANSWER: d
8. During the rising phase of the action potential,
(a) P K+ is much greater than P Na+.
(b) P Na+ is much greater than P K+.
(c) P K+ is the same as P Na+.
(d) Na+ efflux occurs.
(e) Two of these answers.
ANSWER: b
9. Which of the following is not a graded potential?
(a) end-plate potential
(b) action potential
(c) slow-wave potential
(d) receptor potential
(e) postsynaptic
potential ANSWER: b
10. Which of the following is responsible for
the falling phase of an action potential?
(a) opening of Na+ gates.
2 Chapter Four
, (b) Na+-K+ pump restoring the ions to their 16. An action potential develops when:
original locations. (a) Threshold voltage is reached.
(c) greatly increased permeability to Na+. (b) Voltage-gated Na+ channels open and the
(d) ATP-ase destroying the energy supply that membrane reaches about -60 millivolts.
was maintaining the action potential at its peak. (c) Spatial and/or temporal summation of
(e) none of these answers. graded potentials occurs to a great enough
extent.
ANSWER: e (d) Depolarization of the axon occurs.
(e) All of these answers.
11. The rising phase of the action potential is due to:
(a) calcium equilibrium. ANSWER: e
(b) potassium efflux.
(c) potassium influx. 17. Myelinated axons conduct impulses much
(d) sodium efflux. faster because:
(e) sodium influx. (a) The myelin insulates the axon.
(b) Channels only have to open at the nodes.
ANSWER: e (c) Voltage is not lost along myelinated areas.
(d) Of saltatory conduction.
12. The falling phase of the action potential is due to: (e) All of these answers.
(a) calcium equilibrium.
(b) potassium efflux. ANSWER: e
(c) potassium influx.
(d) sodium efflux. 18. At the peak of an action potential,
(e) sodium influx. (a) The electrical gradient for K+ tends to move
this ion outward.
ANSWER: b (b) The concentration gradient for K+ tends to
move this ion outward.
13. When an excitatory neurotransmitter binds to (c) K+ permeability greatly increases.
a nicotinic receptor: (d) Two of these answers.
(a) voltage-gated Na+ channels open. (e) All of these answers.
(b) voltage-gated K+ channels open.
(c) chemically-gated Na+ channels open. ANSWER: e
(d) voltage-gated Cl- channels open.
(e) none of these answers. 19. Which of the following statements concerning
the absolute refractory period is inaccurate?
ANSWER: c (a) The absolute refractory period refers to
the period of time during which another
14. When chemically-gated Na+ channels open: action potential cannot be initiated in a patch
(a) The membrane hyperpolarizes. of membrane that has just undergone an
(b) The membrane repolarizes. action potential, no matter how strong the
(c) The membrane depolarizes. stimulus.
(d) The membrane becomes more negative. (b) The absolute refractory period corresponds
(e) The membrane is inhibited. to the time period during which the Na+ gates are
first opened and then closed and inactivated.
ANSWER: c (c) Immediately following the absolute refractory
period, the patch of nerve fiber membrane that
15. When a membrane is stimulated due to opening has just under- gone an action potential can be
of chemically-gated Na+ channels: restimulated only by a stronger stimulus than is
(a) An impulse is propagated. usually necessary.
(b) A graded potential is established.
(d) The absolute refractory period occurs during
(c) An action potential is established. the after hyperpolarization phase of the action
(d) The voltage becomes more negative. potential.
(e) The voltage stays the same. (e) The absolute and relative refractory
periods assure the unidirectional spread of the
ANSWER: b action potential down the nerve fiber away
from the initial site of activation.
Page 3 of 24
Principles of Neural and Hormonal Communication
TEST QUESTIONS
Multiple Choice action potential.
1. A change in a membrane potential from +30
mV to –70 mV is an example of:
(a) depolarization.
(b) hyperpolarization.
(c) polarization.
(d) repolarization.
(e) zero potential.
ANSWER: d
2. The negative charge established along a nerve
cell membrane is due to:
(a) movement of Na+ into the cell.
(b) movement of proteins out of the cell.
(c) higher permeability of K+ relative to Na+.
(d) intracellular protein anions.
(e) both (c) and (d).
ANSWER: e
3. The cells of excitable and nonexcitable
tissues share which of the following
properties?
(a) a threshold potential.
(b) a resting membrane potential.
(c) an ability to open the Na+ gates.
(d) all of these answers.
(e) none of these answers.
ANSWER: b
4. Which term below best describes an excitable
when a resting membrane potential is
present?
(a) polarized.
(b) depolarized.
(c) hyperpolarized.
(d) repolarized.
(e) nonpolarized.
ANSWER: a
5. A threshold potential is:
(a) the potential achieved when two opposing
forces acting upon an ion (concentration and
electrical gradients) achieve a state of
equilibrium.
(b) the peak potential achieved during an
Page 1 of 24
, (c) the point at which there is an
explosive increase in Na+ permeability.
(d) the potential at which K+
permeability increases.
(e) always a positive potential.
ANSWER: c
6. A change in a membrane potential from –70
mV to –60mV is an example of:
(a) depolarization.
(b) hyperpolarization.
(c) polarization.
(d) repolarization.
(e) zero potential.
ANSWER: a
7. Graded potentials:
(a) are local changes in membrane potential
that occur in varying degrees of magnitude.
(b) serve as short-distance signals.
(c) serve as long-distance signals.
(d) both (a) and (b).
(e) both (a) and (c).
ANSWER: d
8. During the rising phase of the action potential,
(a) P K+ is much greater than P Na+.
(b) P Na+ is much greater than P K+.
(c) P K+ is the same as P Na+.
(d) Na+ efflux occurs.
(e) Two of these answers.
ANSWER: b
9. Which of the following is not a graded potential?
(a) end-plate potential
(b) action potential
(c) slow-wave potential
(d) receptor potential
(e) postsynaptic
potential ANSWER: b
10. Which of the following is responsible for
the falling phase of an action potential?
(a) opening of Na+ gates.
2 Chapter Four
, (b) Na+-K+ pump restoring the ions to their 16. An action potential develops when:
original locations. (a) Threshold voltage is reached.
(c) greatly increased permeability to Na+. (b) Voltage-gated Na+ channels open and the
(d) ATP-ase destroying the energy supply that membrane reaches about -60 millivolts.
was maintaining the action potential at its peak. (c) Spatial and/or temporal summation of
(e) none of these answers. graded potentials occurs to a great enough
extent.
ANSWER: e (d) Depolarization of the axon occurs.
(e) All of these answers.
11. The rising phase of the action potential is due to:
(a) calcium equilibrium. ANSWER: e
(b) potassium efflux.
(c) potassium influx. 17. Myelinated axons conduct impulses much
(d) sodium efflux. faster because:
(e) sodium influx. (a) The myelin insulates the axon.
(b) Channels only have to open at the nodes.
ANSWER: e (c) Voltage is not lost along myelinated areas.
(d) Of saltatory conduction.
12. The falling phase of the action potential is due to: (e) All of these answers.
(a) calcium equilibrium.
(b) potassium efflux. ANSWER: e
(c) potassium influx.
(d) sodium efflux. 18. At the peak of an action potential,
(e) sodium influx. (a) The electrical gradient for K+ tends to move
this ion outward.
ANSWER: b (b) The concentration gradient for K+ tends to
move this ion outward.
13. When an excitatory neurotransmitter binds to (c) K+ permeability greatly increases.
a nicotinic receptor: (d) Two of these answers.
(a) voltage-gated Na+ channels open. (e) All of these answers.
(b) voltage-gated K+ channels open.
(c) chemically-gated Na+ channels open. ANSWER: e
(d) voltage-gated Cl- channels open.
(e) none of these answers. 19. Which of the following statements concerning
the absolute refractory period is inaccurate?
ANSWER: c (a) The absolute refractory period refers to
the period of time during which another
14. When chemically-gated Na+ channels open: action potential cannot be initiated in a patch
(a) The membrane hyperpolarizes. of membrane that has just undergone an
(b) The membrane repolarizes. action potential, no matter how strong the
(c) The membrane depolarizes. stimulus.
(d) The membrane becomes more negative. (b) The absolute refractory period corresponds
(e) The membrane is inhibited. to the time period during which the Na+ gates are
first opened and then closed and inactivated.
ANSWER: c (c) Immediately following the absolute refractory
period, the patch of nerve fiber membrane that
15. When a membrane is stimulated due to opening has just under- gone an action potential can be
of chemically-gated Na+ channels: restimulated only by a stronger stimulus than is
(a) An impulse is propagated. usually necessary.
(b) A graded potential is established.
(d) The absolute refractory period occurs during
(c) An action potential is established. the after hyperpolarization phase of the action
(d) The voltage becomes more negative. potential.
(e) The voltage stays the same. (e) The absolute and relative refractory
periods assure the unidirectional spread of the
ANSWER: b action potential down the nerve fiber away
from the initial site of activation.
Page 3 of 24
