Deck 4: Principles of Neural and Hormonal Communication

Question 1

During the rising phase of the action potential,

A)PK+ is much greater than PNa+
B)PNa+ is much greater than PK+
C)PK+ is the same as P Na+
D)Na+ efflux occurs
E)b and d are true

Answer 1

B

Question 2

The falling phase of the action potential is due to

A)calcium influx
B)potassium efflux
C)chloride influx
D)sodium efflux
E)the action of Na+-K+ pumps

Answer 2

B

Question 3

At the peak of an action potential,

A)the diffusion of Na+ through voltage-gated channels ceases
B)the concentration gradient for K+ promotes the movement of this ion out of the cell
C)K+ permeability greatly increases
D)the electrical gradient promotes the diffusion of K+ out of the cell
E)all of the above are true

Answer 3

E

Question 4

Myelinated axons conduct impulses much faster because

A)the myelin insulates the axon
B)ion channels only have to open at the nodes
C)voltage is not lost along myelinated areas
D)saltatory conduction occurs
E)all of the above are true

Question 5

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

Question 6

Which of the following is responsible for the falling phase of an action potential?

A)opening of Na+ gates
B)Na+-K+ pump restoring the ions to their original locations
C)greatly increased permeability to Na+
D)Na+ efflux
E)none of these

Question 7

Which term best describes an excitable cell when a resting membrane potential is present?

A)polarized
B)depolarized
C)hyperpolarized
D)repolarized
E)nonpolarized

Question 8

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

Question 9

Because of the presence of both activation and inactivation gates, voltage-gated Na⁺ channels can

A)be closed but capable of opening
B)be activated
C)be closed and not capable of opening
D)exhibit all of the above events
E)exhibit only the a and b events

Question 10

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

Question 11

Graded potentials

A)are local changes in membrane potential that occur in varying degrees of magnitude
B)are weak action potentials
C)serve as long-distance signals
D)are only depolarizations
E)always lead to action potentials

Question 12

An action potential on a neuron develops when

A)threshold voltage is reached on an axon
B)voltage-gated Na+ channels open
C)spatial or temporal summation of graded potentials occurs to a great enough degree
D)the axon hillock reaches threshold voltage
E)any of the above events occur

Question 13

When chemically-gated Na⁺ channels open, the membrane

A)hyperpolarizes
B)repolarizes
C)depolarizes
D)becomes more negative
E)is inhibited

Question 14

In most excitable cells, the rising phase of the action potential is due to

A)calcium efflux
B)potassium efflux
C)chloride influx
D)potassium influx
E)sodium influx

Question 15

Which of the following is/are found in all cells of excitable and nonexcitable tissues?

A)a threshold potential
B)a resting membrane potential
C)gated ion channels
D)all of the above characteristics
E)mechanically-gated channels

Question 16

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 action potential
C)the point at which there is an explosive increase in Na+ or Ca₂₊ permeability
D)the potential at which K+ permeability increases
E)always a positive potential

Question 17

Which statement is not accurate about the absolute refractory period?

A)Another stimulus, regardless of its strength, cannot initiate another action potential during this period
B)During this period, voltage-gated Na+ channels open, then close but are inactivated
C)Immediately following this period, the membrane can experience another action potential if the stimulus is strong enough
D)This period occurs during the after hyperpolarization phase of the action potential
E)This period ensures a unidirectional spread of the action potential down a nerve fiber

Question 18

Opening either a chemically-gated Na⁺ channel or a chemically-gated K⁺ channel during the resting potential would cause

A)an impulse to be propagated
B)a graded potential
C)an action potential
D)the membrane's potential to becomes more negative
E)threshold voltage will be reached

Question 19

The negative charge established along the cytosolic border a nerve cell membrane is due to

A)movement of sodium ions into the cell
B)movement of proteins out of the cell
C)higher permeability of K+ relative to Na+
D)movement of proteins through membrane channels
E)both b and d

Question 20

Binding of an excitatory neurotransmitter to a postsynaptic neuron causes

A)voltage-gated Na+ channels open
B)voltage-gated K+ channels open
C)chemically-gated Na+ channels open
D)voltage-gated Cl- channels open
E)chemically-gated Cl- channels open

Question 21

Which statement is true about the absolute refractory period?

A)It ensures that action potentials move in only one direction along a nerve fiber.
B)It is the period when the membrane can undergo another action potential, but only if the stimulus is strong enough.
C)It is the time during an action potential when voltage-gated Na+ channels are in their "closed but capable of opening" conformation.
D)places a lower limit on the frequency with which a neuron can conduct action potentials.
E)All of the above statements are true.

Question 22

Which statement is incorrect?

A)A local current can occur in myelinated nerve fibers
B)A local current flow from an active to an adjacent inactive area decreases the potential in the inactive area to threshold
C)Contiguous conduction occurs along Schwann cells on myelinated nerve fibers
D)Saltatory conduction is faster than contiguous conduction
E)A local current can occur in myelinated nerve fibers

Question 23

When the membrane potential is +15 mV, that portion of the membrane

A)is at the normal resting potential
B)has a positively-charged inside border
C)is more permeable to Ca²⁺ than normal
D)is in the after hyperpolarization phase of an action potential
E)is in a hyperpolarized state

Question 24

The trigger zone of a neuron

A)is located at the axon hillock
B)is located in the axon terminal
C)contains only chemically gated channels
D)conducts graded potentials to the axon
E)causes action potentials to move toward the cell body and dendrites

Question 25

An IPSP is

A)produced by increased permeability to Na+ and K+
B)produced by increased permeability to K+ or Cl-
C)a hyperpolarization of the presynaptic cell
D)a decrease in the postsynaptic membrane potential
E)an decrease in the presynaptic membrane potential

Question 26

The period following an action potential during which a membrane cannot experience another action potential

A)is the absolute refractory period
B)occurs during the time after the Na+ gates have opened until they are restored to their "closed but capable of opening" state
C)prevents the action potential from spreading back over the part of the membrane where the impulse has just passed
D)includes the time when Na+ gates are in a "closed and not capable of opening" state
E)includes all of the above

Question 27

Spatial summation occurs on a postsynaptic neuron would occur when

A)several EPSPs from a single presynaptic input sum to reach threshold
B)EPSPs from several presynaptic inputs sum to reach threshold
C)there is simultaneous interaction of an EPSP and an IPSP
D)several IPSPs from a single presynaptic input sum to hyperpolarize the membrane
E)none of the above take place

Question 28

At an excitatory synapse, an action potential in the presynaptic neuron increases

A)the membrane potential of the postsynaptic cell membrane
B)the permeability of the postsynaptic cell to Na+
C)the permeability of the postsynaptic cell to Cl-
D)the presynaptic neuron's membrane potential
E)all of the above

Question 29

Saltatory conduction

A)occurs in unmyelinated nerve fibers
B)is slower than contiguous conduction because myelin acts as an insulator to slow the impulse
C)involves the impulse jumping from one node of Ranvier to the adjacent node
D)refers to the action potential spreading from one Schwann cell to the adjacent Schwann cell
E)occurs along dendrites and axons of certain neurons

Question 30

Which statement about graded potentials is false?

A)They are decremental.
B)They travel only short distances.
C)They are self-propagating.
D)They may contribute to the development of an action potential.
E)They travel in both directions along the membrane.

Question 31

When is a plasma membrane more permeable to K⁺ than to Na⁺?

A)During the resting potential
B)During the rising phase of an action potential
C)During the rising phase of a graded potential
D)Both a and b
E)Both b and c

Question 32

Permeability of which ion is affected by a positive feedback mechanism once threshold is reached?

A)sodium
B)potassium
C)calcium
D)chloride
E)protein

Question 33

Local current flow

A)occurs only on dendrites of neurons
B)causes impulses to move from the axon hillock toward the neuron's cell body
C)involves current flowing between active and adjacent inactive areas, thereby bringing the inactive areas to threshold
D)occurs only on axons of neurons
E)does not occur on all excitable membranes

Question 34

The relative refractory period occurs after the action potential is complete because of

A)the lingering inactivation of the voltage-gated Na+ channels
B)the slowness of the voltage-gated K+ channels
C)the action of the sodium-potassium pumps
D)both a and b
E)both b and c

Question 35

At an inhibitory synapse, the postsynaptic membrane experiences

A)an increase in permeability to both Na+ and K+
B)an increase in membrane potential
C)hyperpolarization
D)an influx of cations
E)all of the above

Question 36

If a neuron were experimentally stimulated at both ends simultaneously, then

A)the action potentials would pass in the middle and travel to the opposite ends
B)the action potentials would meet in the middle and then be propagated back to their starting positions
C)the action potentials would stop as they met in the middle
D)the strongest action potential would override the weaker action potential
E)summation would occur when the action potentials met in the middle, resulting in a two larger action potentials traveling in opposite directions

Question 37

During the peak of the action potential, the membrane becomes most permeable to

A)sodium
B)potassium
C)calcium
D)chloride
E)protein

Question 38

Select the incorrect statement about the action potential.

A)It has an all-or-none characteristic
B)It has a refractory period
C)It is triggered by depolarization to threshold
D)It occurs along a plasma membrane
E)It speeds up transmission by summation

Question 39

If neuron X is repeatedly stimulating neuron Z with an excitatory neurotransmitter, then

A)several simultaneous action potentials might be initiated on neuron Z
B)the membrane potential on neuron Z would increase
C)spatial summation would be occurring on neuron Z
D)the postsynaptic neuron in this situation would have to reach threshold voltage
E)none of the above would have to occur

Question 40

What is responsible for development of the resting membrane potential?

A)Leak channels
B)Gated channels
C)Ion pumps
D)both a and b
E)both a and c

Question 41

A hypothetical postsynaptic neuron has three presynaptic inputs-X, Y, and Z.When X and Y are stimulated simultaneously, the postsynaptic neuron undergoes an action potential, yet when X and Z are stimulated simultaneously, there is no change in the postsynaptic neuron's potential.What can you logically conclude?

A)Y and Z are both excitatory.
B)Y and Z are both inhibitory.
C)Y is excitatory and Z is inhibitory.
D)Y is inhibitory and Z is excitatory.
E)Not enough information to answer.

Question 42

Select the neuropeptide.

A)acetylcholine
B)dopamine
C)epinephrine
D)cholecystokinin
E)glycine

Question 43

Sequence the following events correctly.

A)1, 2, 3, 5, 4
B)1, 4, 3, 2, 5
C)2, 1, 5, 4, 3
D)3, 1, 4, 5, 2
E)5, 4, 3, 1, 2

Question 44

Which channel type is sensitive to serotonin?

A)voltage-gated
B)chemically-gated
C)mechanically-gated
D)acoustically-gated
E)none of these

Question 45

The normal direction for the movement of an action potential along part of a neuron is from

A)axon hillock to cell body
B)axon terminal to collateral axon
C)axon to dendrite
D)cell body to receptor
E)dendrite to cell body

Question 46

In divergence,

A)many presynaptic neurons synapse with one postsynaptic cell
B)one dendrite contacts many presynaptic neurons
C)action potentials initiated in the axon diminish as they spread to axon terminals
D)one axon synapses with many other cells
E)many axons spread out from one cell body

Question 47

Which statement is correct?

A)In presynaptic inhibition, another neuron inhibits an excitatory presynaptic input.
B)An IPSP depresses information fed into the cell from an inhibitory presynaptic input.
C)Not all axon terminals of an inhibitory neuron release inhibitory neurotransmitter.
D)During presynaptic inhibition, there is no change in presynaptic membrane potential.
E)An IPSP decreases the potential of the postsynaptic neuron.

Question 48

Neuromodulators

A)bind to receptors at synapses
B)contribute directly to EPSPs
C)contribute directly to IPSPs
D)may influence neurotransmitter production
E)speed up contiguous impulse conduction

Question 49

The nodes of Ranvier are

A)action potential recordings
B)breaks in the myelin covering
C)spaces between neurons
D)specialized cells around axons
E)structures on axon terminals that release neurotransmitter

Question 50

Neuropeptides

A)are sometimes co-secreted along with classical neurotransmitters
B)are synthesized in the cytosol of the axon terminal
C)act at the subsynaptic membrane of the postsynaptic neuron
D)act slowly to bring about an IPSP or EPSP
E)are larger molecules than classical neurotransmitters

Question 51

Presynaptic facilitation results from

A)alteration of calcium permeability
B)continued generation of EPSPs
C)neuromodulator effects
D)increased neurotransmitter production
E)none of the above

Question 52

The nucleus of a neuron is housed in the

A)axon
B)axon hillock
C)cell body
D)collaterals
E)dendrites

Question 53

Select the last step for synaptic signaling when the action potential arrives at the axon terminal of a presynaptic neuron.

A)A neurotransmitter is released by exocytosis.
B)Calcium flows in the synaptic knob.
C)The neurotransmitter combines with a protein receptor on the subsynaptic membrane.
D)The permeability is altered in a postsynaptic neuron.
E)Sodium influx occurs at the axon terminals

Question 54

Drugs may influence synaptic transmission by

A)altering the formation of neurotransmitters
B)blocking neurotransmitter reuptake
C)blocking receptors
D)blocking channels
E)all of the above

Question 55

In convergence,

A)many presynaptic cells synapse with a single postsynaptic cell
B)one axon directly influences the activity of many other cells
C)many dendrites converge on one cell body
D)all of the above are true
E)none of the above are true

Question 56

With presynaptic inhibition,

A)an IPSP occurs on the postsynaptic cell
B)all excitatory information being fed into the cell is prevented
C)the release of excitatory neurotransmitter from a specific presynaptic excitatory input is depressed.
D)at least two of the above occur.
E)none of the above occur.

Question 57

Which statement is incorrect?

A)Inhibitory synapses cause postsynaptic hyperpolarization.
B)An inhibitory synapse may result in postsynaptic sodium channel opening.
C)An inhibitory synapse may result in increased postsynaptic potassium efflux.
D)An excitatory synapse causes depolarization of postsynaptic membranes.
E)An excitatory synapse increases sodium permeability.

Question 58

Neuron A and neuron B release a minimal amount of neurotransmitter simultaneously onto neuron C, causing neuron C to experience an action potential.This is an example of

A)temporal summation
B)spatial summation
C)convergence
D)both a and c
E)both b and c

Question 59

Select the first step for synaptic signaling when the action potential arrives at the axon terminal of a presynaptic neuron.

A)A neurotransmitter is released by exocytosis.
B)Calcium flows into the synaptic knob.
C)The neurotransmitter combines with a protein receptor on the subsynaptic membrane.
D)The permeability is altered in a postsynaptic neuron.
E)The axon terminal depolarizes.

Question 60

Which statement about a graded potential is false?

A)It can be a depolarization.
B)It can be a hyperpolarization.
C)It can be summated.
D)It has a refractory period.
E)It occurs in a specialized area of the membrane.

Question 61

Which of the following is least related to a description of contiguous conduction on a neuron?

A)dendrite
B)action potential
C)refractory period
D)unmyelinated axon
E)nondecremental propagation

Question 62

All of the following may be considered second messengers except

A)inositol triphosphate
B)calcium ions
C)phosphodiesterase
D)cyclic AMP
E)diacylglycerol

Question 63

If neuron Y's neurotransmitter is causing neuron X's membrane potential to decrease, then we would logically conclude that this neurotransmitter causes

A)increased PNa+ and PK+
B)increased PK+ or PCl-
C)increased permeability to protein anions
D)increased permeability to calcium ions
E)None of the above

Question 64

When comparing saltatory conduction to contiguous conduction, saltatory conduction

A)is the only method that occurs along both dendrites and axons
B)is the only method that utilizes a positive feedback cycle
C)requires more Na+-K+ activity after repolarization is complete
D)causes the loss of fewer K+ ions during repolarization
E)occurs along unmyelinated axons

Question 65

The passive current flow of a graded potential fades quickly.

Question 66

In a graded potential, the direction of current flow is designated by the movement of positive charges.

Question 67

Which of the following is not true for lipophilic hormones?

A)Cells do not store them.
B)They are all derived from cholesterol.
C)They are bound to protein in the blood.
D)They typically activate genes.
E)Only a small portion of the hormone is biologically active.

Question 68

If neuron X causes hyperpolarization, then what does it cause in a postsynaptic neuron?

A)Increased PNa+ and PK+
B)Increased PK+ or PCl-
C)Increased influx of protein anions
D)Increased permeability to calcium ions
E)Either b or c

Question 69

The Na⁺ and K⁺ channels that open and close during an action potential are voltage-gated channels.

Question 70

Threshold potential is the peak potential achieved during an action potential.

Question 71

If neuron X causes hyperpolarization of neuron Z but neuron Y causes depolarization of neuron Z, what change would you expect in neuron Z if it is stimulated by both X and Y simultaneously?

A)a significant increase in membrane potential
B)a significant decrease in membrane potential
C)temporal summation leading to an impulse on Z
D)simultaneous influx and efflux of cations or simultaneous influx of cations and efflux of anions
E)an increase in the resting membrane potential

Question 72

Which of the following characteristics is least related to steroid hormones?

A)Binds to intracellular receptor
B)Transported bound in the blood
C)May bind to hormone response element
D)Stimulate protein synthesis
E)Utilize a G protein

Question 73

Tetanus toxin

A)binds with glycine receptors, thus blocking the action of this inhibitory neurotransmitter
B)destroys dopamine in the region of the brain involved in controlling complex movements
C)prevents the release of GABA that inhibits neurons that innervate skeletal muscle cells
D)promotes presynaptic facilitation
E)causes IPSPs to occur on skeletal muscle cell membranes

Question 74

If neurotransmitter from X causes a slight hyperpolarization of a postsynaptic cell, then

A)the synapse is excitatory
B)the synapse is inhibitory
C)the postsynaptic cell's membrane potential is becoming less negative
D)the postsynaptic cell's membrane potential is becoming more positive
E)b, c, and d are occurring

Question 75

A spike is another name for the axon of a neuron.

Question 76

If an excitatory neuron and an inhibitory neuron both stimulate the same postsynaptic neuron simultaneously, what can you know for sure is happening in the postsynaptic neuron?

A)it would likely reach threshold
B)its permeability to cations and anions would decrease
C)its resting membrane potential would increase
D)it would be experiencing temporal summation
E)increased permeability to cations

Question 77

Which of the following is least related to a neuromodulator?

A)axonal transport
B)dense-core vesicle
C)cholecystokinin
D)synaptic vesicle
E)neuropeptide

Question 78

Identify a second-messenger.

A)Insulin
B)G protein
C)G protein coupled receptor
D)Adenylyl cyclase
E)None of the above

Question 79

Only neurons and muscle cells establish resting membrane potentials.

Question 80

If neurotransmitter from Y causes the membrane potential of the postsynaptic cell to decrease slightly, then

A)the synapse is excitatory
B)the postsynaptic membrane's potential will be farther away from threshold
C)the postsynaptic membrane causes an EPSP on the presynaptic membrane
D)neurotransmitter from Y causes an IPSP on the presynaptic membrane
E)both a and c are correct