Deck 4: Neural Conduction and Synaptic Transmission

Question 1

Which of the following is a passive force that acts to encourage Na+ ions to enter resting neurons?

A) random motion, which tends to move ions down their concentration gradients
B) electrostatic pressure, which forces ions down their electrostatic gradients
C) sodium-potassium pumps, which distribute Na+ and K+ ions equally
D) both A and B
E) both A and C

Answer 1

both A and B

Question 2

According to the theory of Hodgkin and Huxley,

A) Na+ ions continuously leak out of a resting neuron.
B) Na+ ions are continuously pumped into a resting neuron.
C) K+ ions continuously leak out of a resting neuron.
D) K+ ions are continuously pumped out of a resting neuron.
E) both A and B

Answer 2

K+ ions continuously leak out of a resting neuron.

Question 3

In its resting state, a neuron is said to be

A) polarized.
B) depolarized.
C) hypopolarized.
D) hyperpolarized.
E) firing.

Answer 3

polarized.

Question 4

"Reptilian stare" is sometimes used to describe the widely opened, unblinking eyes and motionless face of

A) Parkinson's disease.
B) multiple sclerosis.
C) old age.
D) infancy.
E) Alzheimer's disease.

Question 5

Na+ ions are encouraged to move into neurons by

A) nonrandom assignment.
B) electrostatic pressure.
C) the sodium-potassium pump.
D) selective ion channels.
E) nonrandom movement.

Question 6

A change in the resting potential of a postsynaptic dendrite from -70 mV to -72 mV is called

A) an IPSP.
B) an EPSP.
C) a depolarization.
D) both A and C
E) both B and C

Question 7

Na+ ions are continuously forced into neurons by

A) their high internal concentration.
B) their high external concentration.
C) the negative resting potential.
D) both B and C
E) none of the above

Question 8

The tips of intracellular recording electrodes are

A) about the size of a neuron.
B) too small to be seen with the naked eye.
C) less than one thousandth of a millimeter in diameter.
D) both B and C
E) none of the above

Question 9

Parkinson's disease is treated with

A) dopamine.
B) serotonin.
C) acetylcholine.
D) norepinephrine.
E) L-DOPA.

Question 10

Hyperpolarization is to depolarization as

A) inhibitory is to excitatory.
B) EPSPs are to IPSPs.
C) APs are to IPSPs.
D) APs are to EPSPs.
E) many APs are to few APs.

Question 11

Salts in solution separate into positively and negatively charged

A) membrane potentials.
B) EPSPs.
C) IPSPs.
D) ions.
E) crystals.

Question 12

At rest,

A) a neuron has a membrane potential of about -70 mV.
B) the electrical charge outside the neuron is 70 mV less than inside the neuron.
C) a neuron is polarized.
D) all of the above
E) both A and C

Question 13

Outside the membranes of resting neurons, there are many more

A) inhibitory neurotransmitters.
B) neurotransmitters.
C) Na+ ions.
D) K+ ions.
E) nuclei.

Question 14

EPSPs are

A) graded responses.
B) postsynaptic responses.
C) transmitted decrementally.
D) depolarizations.
E) all of the above

Question 15

A membrane potential is the difference in electrical charge between

A) neuron membranes.
B) synapses and cell bodies.
C) the inside and outside of a cell.
D) nuclei and tracts.
E) ganglia and nerves.

Question 16

Dopamine is not an effective treatment for Parkinson's disease because

A) dopaminergic neurons are restricted to the PNS.
B) Parkinson's disease is a cholinergic dysfunction.
C) Parkinson's disease is a noradrenergic dysfunction.
D) d'Orta is the treatment of choice.
E) dopamine does not readily penetrate the blood-brain barrier.

Question 17

Contributing to the unequal distribution of ions on either side of a resting neural membrane

A) is random ion movement.
B) are electrostatic gradients.
C) are sodium-potassium pumps.
D) both A and B
E) both B and C

Question 18

Sodium-potassium pumps are

A) integrators.
B) refractory.
C) transporters.
D) excitatory.
E) inhibitory.

Question 19

Sodium-potassium pumps maintain the resting membrane potential by transporting

A) Na+ ions into neurons.
B) K+ ions into neurons.
C) Na+ ions out of neurons.
D) both A and B
E) both B and C

Question 20

Ions pass through the neural membrane via specialized pores called

A) gap junctions.
B) PSPs.
C) ion channels.
D) vesicles.
E) connexons.

Question 21

Conduction of action potentials along an axon is

A) instantaneous.
B) decremental.
C) nondecremental.
D) entirely passive.
E) always saltatory.

Question 22

The conduction of an action potential along any axon is mediated by the action of

A) nodes of Ranvier.
B) voltage-activated ion channels.
C) ligand-activated ion channels.
D) myelin.
E) EPSPs.

Question 23

How far do most postsynaptic potentials travel before they die out.

A) to the axon hillock
B) to the terminal buttons
C) no more than a couple of millimeters
D) about 50 millimeters
E) both B and D

Question 24

The fact that the intensity of stimulation is related to the rate of neural firing is attributable to the

A) absolute refractory period.
B) relative refractory period.
C) voltage gating in the buttons of the neuron.
D) sodium-potassium pump.
E) ligand gating in the buttons of the neuron.

Question 25

A neuron normally fires when

A) its sodium-potassium pumps are stimulated.
B) there is an EPSP.
C) there is an IPSP.
D) the degree of depolarization on the axon adjacent to the hillock exceeds the threshold of excitation.
E) its buttons are stimulated.

Question 26

Action potentials are produced by the

A) opening of voltage-activated sodium channels.
B) closing of ligand-activated chloride channels.
C) closing of ligand-activated potassium channels.
D) opening of ligand-activated potassium channels.
E) closing of voltage-activated calcium channels.

Question 27

There are three kinds of spatial summation and

A) one kind of temporal summation.
B) two kinds of temporal summation.
C) three kinds of temporal summation.
D) four kinds of temporal summation.
E) no such thing as temporal summation.

Question 28

Active conduction is to passive conduction as

A) IPSPs are to APs.
B) EPSPs are to IPSPs.
C) APs are to EPSPs.
D) EPSPs are to APs.
E) excitation is to inhibition.

Question 29

IPSP is to EPSP as

A) graded is to nongraded.
B) excitatory is to inhibitory.
C) cable properties are to noncable properties.
D) presynaptic is to postsynaptic.
E) hyperpolarization is to depolarization.

Question 30

The end of the rising phase of an action potential occurs when the

A) sodium channels close.
B) sodium channels open.
C) potassium channels open.
D) potassium channels close.
E) both A and D

Question 31

APs are said to be all-or-none: This means that all APs

A) are the same.
B) in a particular neuron are the same.
C) quickly or not at all.
D) all of the above
E) both A and C

Question 32

The transmission of postsynaptic potentials is

A) active.
B) decremental.
C) extremely rapid.
D) all of the above
E) both B and C

Question 33

Another word for "integration" is

A) "firing."
B) "all-or-none."
C) "summation."
D) "release."
E) "activation."

Question 34

During an action potential, the change in membrane potential associated with the influx of sodium ions triggers the

A) opening of sodium channels.
B) closing of chloride channels.
C) opening of chloride channels.
D) closing of potassium channels.
E) opening of potassium channels.

Question 35

The wave of absolute refractoriness that follows an action potential

A) keeps the action potential from spreading actively back along an axon towards the cell body.
B) increases the firing rate.
C) increases the speed of axonal transmission.
D) produces a second, negative action potential.
E) produces saltatory conduction.

Question 36

The brief period of time immediately after the initiation of an action potential when it is absolutely impossible to initiate another one in the same neuron is called the

A) threshold of excitation.
B) threshold of inhibition.
C) absolute refractory period.
D) IPSP.
E) relative refractory period.

Question 37

After a neuron fires, the resting potential is re-established by the

A) sodium-potassium pump.
B) random movement of ions.
C) refractory period.
D) electrostatic gradient.
E) EPSPs.

Question 38

Neurons do not normally fire more than 1,000 times per second because

A) the absolute refractory period is typically about 1 millisecond.
B) the relative refractory period is typically about 1 millisecond.
C) the total refractory period is typically about 1 millisecond.
D) the sodium-potassium pump cannot repolarize the cell in less than 1 millisecond.
E) higher rates over excite the neuron.

Question 39

Action potentials originate at the

A) terminal buttons.
B) synapses.
C) axon initial segment, adjacent to the axon hillock
D) nodes of Ranvier.
E) nucleus.

Question 40

Which of the following are membrane potentials?

A) EPSPs
B) IPSPs
C) APs
D) all of the above
E) both A and B

Question 41

Nondirected synapses

A) involve the release of neurotransmitter molecules diffusely into the extracellular fluid.
B) include string-of-beads synapses.
C) involve the movement of neurotransmitter molecules across gap junctions.
D) both A and B
E) both B and C

Question 42

Neurons without axons do not

A) generate action potentials.
B) exist.
C) exist in mammals.
D) exist in humans.
E) produce inhibition.

Question 43

Neurotransmitters are often stored in

A) aluminum foil.
B) ribosomes.
C) synaptic vesicles.
D) nodes of Ranvier.
E) the synaptic cleft.

Question 44

Both presynaptic facilitation and inhibition are mediated by

A) axoaxonic synapses.
B) axodendritic synapses.
C) dendrodendritic synapses.
D) axosomatic synapses.
E) both A and D

Question 45

Neurotransmitter molecules are often packaged in vesicles by

A) Golgi complexes.
B) ribosomes.
C) buttons.
D) peptides.
E) microtubules.

Question 46

Neuropeptides are transported in vesicles from the cell body to the buttons at a speed of about

A) 100 meters per minute.
B) 40 centimeters per day.
C) 60 meters per second.
D) 40 meters per minute.
E) 20 meters per second.

Question 47

With respect to the maximum speed of axonal conduction in motor neurons, cats are to humans as

A) 50 is to 100 meters per second.
B) 80 is to 100 meters per second.
C) 25 is to 100 meters per second.
D) 82 is to 100 meters per second.
E) 100 is to 60 meters per second.

Question 48

Prevalent in the cytoplasm of most terminal buttons are

A) nuclei.
B) mitochondria.
C) synaptic vesicles.
D) all of the above
E) both B and C

Question 49

Axodendritic synapses

A) are rare.
B) often terminate on the axon hillock.
C) always terminate on dendrites.
D) sometimes terminate on cell bodies.
E) A and C

Question 50

Many buttons contain two sizes of vesicles; the larger ones typically contain

A) small-molecule neurotransmitters.
B) neuropeptides.
C) acetylcholine.
D) dopamine.
E) glutamate.

Question 51

Peptide neurotransmitters (i.e., neuropeptides) are synthesized in the cell body and

A) stored in the Golgi complex until they are broken down.
B) released by the Golgi complex into the synapse.
C) transported in vesicles along microtubules to the buttons.
D) stored in ribosomes with small-molecule neurotransmitters.
E) transported along the axons to the nodes of Ranvier.

Question 52

Neuropeptides are synthesized in the cell body on

A) ribosomes.
B) the Golgi complex.
C) vesicles.
D) mitochondria.
E) microtubules.

Question 53

Conduction of action potentials in myelinated axons

A) is faster than in unmyelinated axons.
B) is slower than in unmyelinated axons.
C) is possible in only an antidromic direction.
D) requires more energy than in unmyelinated axons.
E) is always inhibitory.

Question 54

In neurons without axons, conduction occurs entirely in the form of

A) passive, decrementally conducted potentials.
B) action potentials.
C) all-or-none potentials.
D) saltatory conduction.
E) excitation.

Question 55

In large myelinated human motor neurons, impulses travel at about

A) the speed of light.
B) 186,000 miles per second.
C) 1 meter per second.
D) 60 meters per second.
E) 100 meters per second.

Question 56

Action potentials can be conducted

A) actively.
B) passively.
C) orthodromically.
D) antidromically.
E) all of the above

Question 57

Conduction of APs from the axon into the cell body and dendrites of a multipolar neuron is

A) extremely rare.
B) antidromic.
C) orthodromic.
D) both A and B
E) both A and C

Question 58

Many neurons contain and release two neurotransmitters. This situation is called

A) covalence.
B) ionotropism.
C) cohabitation.
D) metabotropism.
E) coexistence.

Question 59

The process of neurotransmitter release is referred to as

A) excitation.
B) exocytosis.
C) synthesis.
D) metabolism.
E) expulsion.

Question 60

Vesicles travel from the cell body to the buttons

A) on action potentials.
B) along microtubules.
C) at a rate of about 40 centimeters per second.
D) at a rate of about 40 centimeters per day.
E) both B and D

Question 61

Once released, neurotransmitter molecules typically produce signals in postsynaptic neurons by

A) binding to presynaptic receptors.
B) binding to postsynaptic receptors.
C) entering postsynaptic neurons.
D) binding directly to calcium ions.
E) attaching to vesicles.

Question 62

Neurons recycle

A) neurotransmitter molecules that have been drawn back into the terminal buttons after being released.
B) the breakdown products of neurotransmitter molecules that have been degraded in the synapse by enzymes.
C) vesicles that have been integrated into the button membrane during exocytosis.
D) all of the above
E) none of the above

Question 63

The one enzyme whose function is to deactivate a specific neurotransmitter once it has been released into the synapse is

A) dopamine.
B) L-DOPA.
C) acetylcholine.
D) acetylcholinesterase.
E) a G protein.

Question 64

Autoreceptors of a neuron are sensitive to the neuron's own

A) EPSPs.
B) neurotransmitter.
C) IPSPs.
D) second messengers.
E) APs.

Question 65

The release of neurotransmitter molecules from buttons is often triggered by

A) an efflux of sodium ions.
B) an influx of calcium ions.
C) the sodium-potassium pump.
D) the arrival of an AP at the axon hillock.
E) the release of calcium ions from the buttons.

Question 66

Autoreceptors are commonly found in

A) somas.
B) postsynaptic membranes.
C) presynaptic membranes.
D) synaptic vesicles.
E) ribosomes.

Question 67

In comparison to ionotropic receptors, metabotropic receptors generally produce

A) their effects more rapidly.
B) longer lasting effects.
C) more localized effects.
D) all of the above
E) both A and C

Question 68

In comparison to metabotropic receptors, ionotropic receptors produce effects that

A) are less diffuse.
B) develop more rapidly.
C) are more enduring.
D) all of the above
E) both A and B

Question 69

Metabotropic receptors are linked to

A) ligand-activated ion channels.
B) signal proteins and G proteins.
C) ionotropic receptors.
D) vesicles.
E) receptor subtypes.

Question 70

In comparison to ionotropic receptors, metabotropic receptors

A) are more prevalent.
B) produce longer lasting effects.
C) produce effects that are more diffuse.
D) produce effects that take longer to develop.
E) all of the above

Question 71

Second messengers are formed in the

A) presynaptic neuron.
B) postsynaptic neuron.
C) synaptic cleft.
D) vesicles.
E) mitochondria.

Question 72

A ligand of acetylcholine is a substance that

A) binds to acetylcholine.
B) stimulates acetylcholine's synthesis.
C) facilitates acetylcholine's release.
D) degrades acetylcholine.
E) inhibits acetylcholine.

Question 73

After release, neurotransmitters are deactivated in the synapse by

A) reuptake.
B) enzymatic degradation.
C) G proteins.
D) all of the above
E) both A or B

Question 74

Which of the following are thought to play a role in reducing excessive neurotransmitter release?

A) dendritic receptors
B) autoreceptors
C) dendritic spines
D) postsynaptic receptors
E) somatic receptors

Question 75

After release, most neurotransmitters are deactivated by

A) reuptake.
B) synaptic enzymes.
C) the postsynaptic receptors.
D) deactivating enzymes.
E) ribosomes.

Question 76

Second messengers can

A) be synthesized in response to activation of metabotropic receptors.
B) influence metabolic activities of the cell.
C) induce IPSPs or EPSPs.
D) bind to DNA to influence protein synthesis.
E) all of the above

Question 77

Which of the following is currently thought to be a valid general principle of synaptic transmission?

A) Each neuron releases only one neurotransmitter.
B) Each neurotransmitter acts on only one receptor subtype.
C) All receptors are in postsynaptic membranes.
D) All neurotransmitters are released into the synaptic cleft.
E) none of the above

Question 78

There is only one neurotransmitter that is known to be deactivated in the synaptic cleft by enzymatic degradation; this neurotransmitter is

A) dopamine.
B) acetylcholine.
C) acetylcholinesterase.
D) norepinephrine.
E) glutamate.

Question 79

When a small-molecule neurotransmitter molecule binds to an ionotropic receptor, the

A) cell fires.
B) cell stops firing.
C) ligand is deactivated.
D) associated ion channel opens or closes.
E) EPSP gradually increases.

Question 80

Ionotropic receptors are linked to

A) ribosomes.
B) neurotransmitters.
C) ligand-activated ion channels.
D) vesicles.
E) G proteins.