Deck 3: Synapses

Question 1

Only sensory neurons are found in a reflex arc.

Answer 1

False

Question 2

A reflex arc consists only of sensory neurons.

Answer 2

False

Question 3

Inhibitory synapses actively suppress excitatory responses.

Answer 3

True

Question 4

The amount of temporal summation depends on the rate of stimulation.

Question 5

At synapses, the cell that receives the message is called the presynaptic neuron.

Question 6

Neurotransmitter levels in the brain can be affected by changes in diet.

Question 7

Transmission of information between neurons occurs in the same way as transmission along the axon.

Question 8

Most excitatory post-synaptic potentials result in an action potential.

Question 9

Most neurons have a spontaneous firing rate, a periodic production of action potentials even without synaptic input.

Question 10

At synapses, the cell that delivers the message is called the presynaptic neuron.

Question 11

Gases can be used as neurotransmitters.

Question 12

Graded potentials can be depolarizations or hyperpolarizations.

Question 13

Spatial summation is the result of synaptic inputs from different locations arriving at the same time.

Question 14

Reflexive flexion and extension of a dog's legs can still occur when the spinal cord is disconnected from the brain.

Question 15

Chemical communication between neurons is faster than electrical communication within neurons.

Question 16

Electrical communication between neurons is faster than chemical communication within neurons.

Question 17

Most of the known neurotransmitters are synthesized from amino acids.

Question 18

Some neurotransmitters are monoamines.

Question 19

Most neurons release more than one kind of neurotransmitter.

Question 20

Generally speaking, a neuron will release a greater number of neurotransmitters than what it will respond to with its own receptors.

Question 21

The proper order of a reflex arc is:

A) motor neuron, sensory neuron, interneuron.
B) sensory neuron, motor neuron, interneuron.
C) motor neuron, interneuron, sensory neuron.
D) sensory neuron, interneuron, motor neuron.

Question 22

Marijuana withdrawal is more intense than opiate withdrawal.

Question 23

Whether or not a neurotransmitter is excitatory depends on the response of the postsynaptic receptor.

Question 24

A drug that blocks the effects of a neurotransmitter is an antagonist.

Question 25

Most of the brain's excitatory ionotropic synapses use the neurotransmitter glutamate.

Question 26

Sherrington deduced that transmission at a synapse must be slower than conduction along an axon. This was based on what kind of evidence?

A) temporal summation
B) drugs that increase or inhibit activity at synapses
C) the speed of reflexive responses
D) differences in diameter between axons and dendrites

Question 27

Specialized junctions between neurons are called:

A) nodes of Ranvier.
B) spines.
C) dendrites.
D) synapses.

Question 28

Why is the speed of conduction through a reflex arc slower than the speed of conduction of an action potential along an axon?

A) Transmission between neurons at synapses is slower than along axons.
B) The longer an axon, the slower its velocity.
C) Interneurons have thicker axons than other neurons.
D) There are greater amounts of myelin involved in the reflex arc.

Question 29

Opiates work at the pain receptors in the skin.

Question 30

On the basis of what evidence were the properties of synapses first inferred?

A) the electron microscope
B) single-neuron recordings
C) behavioral observations
D) PET scans

Question 31

Charles S. Sherrington was the first to infer the properties of which of the following?

A) synapses
B) the refractory period
C) the sodium-potassium pump
D) dendrites and axons

Question 32

Marijuana is used medically to enhance memory.

Question 33

Sherrington found that repeated stimuli within a brief time have a cumulative effect. He referred to this phenomenon as:

A) temporal summation
B) spatial summation
C) synaptic summation
D) saltatory summation

Question 34

____ are specialized junctions between neurons.

A) Nodes of Ranvier
B) Synapses
C) Dendrites
D) Spines

Question 35

A drug that blocks the effects of a neurotransmitter is an agonist.

Question 36

A certain weak stimulus produces no reflexive response, but a rapid repetition of that stimulus may produce such a response. What is this phenomenon called?

A) spatial summation
B) temporal summation
C) saltatory conduction
D) synaptic combination

Question 37

Unlike studies with animals, MDMA in humans is harmless to serotonin neurons.

Question 38

Rapid changes in heart rate are probably due to the activity of ionotropic receptors.

Question 39

Metabotropic synapses use a large variety of transmitters.

Question 40

The circuit from sensory neuron to muscle response is called:

A) a reflex arc.
B) a synapse.
C) flexion.
D) extension.

Question 41

Temporal summation is to ____ as spatial summation is to ____.

A) time, location
B) EPSP, IPSP
C) location, time
D) depolarization, hyperpolarization

Question 42

An EPSP is a(n):

A) graded depolarization.
B) depolarization with a rebounding hyperpolarization.
C) graded hyperpolarization.
D) action potential in a reflex arc.

Question 43

A graded depolarization is known as an:

A) EPIP
B) IPSP
C) ESPN
D) EPSP

Question 44

What do temporal summation and spatial summation have in common?

A) Both involve the activity of only two neurons.
B) Both require a response from the brain.
C) Both depend on a combination of visual and auditory stimuli.
D) Both enable a reflex to occur in response to weak stimuli.

Question 45

What ordinarily prevents extensor muscles from contracting at the same time as flexor muscles?

A) the ligaments and tendons that bind them together
B) learned patterns of coordination in the cerebral cortex
C) inhibitory synapses in the spinal cord
D) control of both muscles by different branches of the same axon.

Question 46

What is the primary difference between temporal summation and spatial summation?

A) Only spatial summation can produce an action potential.
B) Spatial summation depends on contributions from more than one sensory neuron.
C) Temporal summation produces a hyperpolarization instead of a depolarization.
D) Spatial summation alters the response of more than one postsynaptic cell.

Question 47

Which of the following statements regarding reflexes would Charles Sherrington most likely agree with?

A) The overall speed of conduction through a reflex arc is faster than conduction along an axon.
B) Repeated stimuli occurring within a brief time can have a cumulative effect.
C) Each neuron physically merges with the next one.
D) Excitatory synapses are more important than inhibitory synapses.

Question 48

The primary difference between an EPSP and an action potential is that:

A) the magnitude of an action potential decreases as it travels along the membrane.
B) EPSPs occur without sodium ions entering the cell.
C) action potentials are always hyperpolarizations.
D) EPSPs are subthreshold events that decay over time and space.

Question 49

What causes an EPSP?

A) the deactivation of cytoplasmic enzymes
B) the opening of sodium channels
C) the opening of potassium channels
D) inherited paranormal psychic abilities

Question 50

Which of the following is NOT true about EPSPs?

A) They decay over time.
B) Their strength decreases with distance.
C) They operate on an all-or-none principle.
D) They are depolarizations.

Question 51

Which of the following is TRUE about EPSPs?

A) It takes two to produce an action potential.
B) They decay over time and space.
C) They can be either excitatory or inhibitory.
D) They occur because potassium gates open.

Question 52

When a vertebrate animal contracts the flexor muscles of a leg, it relaxes the extensor muscles of the same leg. Sherrington considered this evidence for the existence of:

A) spatial summation.
B) temporal summation.
C) inhibitory messages.
D) the delay in transmission at synapses.

Question 53

Which of the following would produce spatial summation?

A) Present two or more weak stimuli at the same time.
B) Start action potentials at both ends of one axon at the same time.
C) Do not allow a flexor muscle to relax before stimulating it again.
D) Present a rapid sequence of weak stimuli.

Question 54

Temporal summation most likely occurs with:

A) infrequent, subthreshold excitation.
B) rapid succession of stimuli that each exceed threshold.
C) infrequent, inhibitory stimuli.
D) rapid succession of subthreshold excitation.

Question 55

Which of the following patterns of post-synaptic excitation will most likely result in an action potential?

A) rapid sequence of EPSPs
B) rapid sequence of IPSPs
C) large number of simultaneous IPSPs
D) large number of simultaneous IPSPs and EPSPs

Question 56

Depolarization is to ____ as hyperpolarization is to ____.

A) excitation; inhibition
B) inhibition; excitation
C) increasing the threshold; decreasing the threshold
D) decreasing the threshold; increasing the threshold

Question 57

Spatial summation refers to:

A) multiple weak stimulations that occur in rapid succession.
B) a decrease in responsiveness after repeated stimulation.
C) multiple weak stimulations that occur at the same time.
D) an increase in the strength of action potentials after repeated stimulation.

Question 58

To measure temporal summation in single cells, researchers:

A) attach electrodes to the scalp.
B) insert an microelectrode into the scalp.
C) collect sodium and potassium ions from nearby glial cells.
D) record depolarizations of the postsynaptic neuron.

Question 59

Like an action potential, an EPSP results from:

A) sodium ions entering the cell.
B) potassium ions entering the cell.
C) sodium ions exiting the cell.
D) potassium ions exiting the cell.

Question 60

Simultaneous weak stimuli at different locations produce a greater reflexive response than one of the stimuli by itself. What is this phenomenon called?

A) Sherrington's law
B) temporal summation
C) spatial summation
D) the all-or-none law

Question 61

Which of the following would most likely result in an IPSP?

A) potassium ions entering the cell
B) sodium ions entering the cell
C) chloride ions entering the cell
D) chloride ions leaving the cell

Question 62

In a reflex arc, the coordination between contraction of certain muscles and relaxation of others is mediated by:

A) glial cells.
B) motor neurons.
C) sensory neurons.
D) interneurons.

Question 63

The "decision" for a neuron to fire is determined by the:

A) number of EPSPs only.
B) spontaneous firing rate.
C) number of IPSPs only.
D) ratio of EPSPs to IPSPs.

Question 64

What determines whether a neuron has an action potential?

A) only the number of EPSPs impinging on an axon
B) only the number of IPSPs impinging on the dendrites
C) the combined effects of EPSPs and IPSPs
D) summation effects of IPSPs

Question 65

Loewi demonstrated that synapses operate by the release of chemicals. He did this by:

A) applying adrenaline directly to the heart muscle.
B) collecting fluid from a stimulated frog's heart, transferring it to another frog's heart, and measuring that heart rate.
C) measuring the speed of a dog's reflexes while the dog was under the influence of various drugs.
D) applying an extract of marijuana in eye drops and discovering that it dilated the pupils.

Question 66

The "spontaneous firing rate" of a neuron refers to:

A) its resting potential.
B) its rate of energy consumption.
C) its rate of producing action potentials even when it is not stimulated.
D) the velocity of its action potentials under normal conditions.

Question 67

The research that firmly established synaptic communication as chemical was:

A) Elliot's adrenaline mimicking sympathetic activation.
B) Loewi's transfer of fluid from stimulated frog hearts.
C) Sherrington's study of reflexes.
D) Eccles's measurement of IPSPs.

Question 68

Increased permeability to which of the following ions would most likely result in an IPSP?

A) sodium
B) potassium
C) calcium
D) bicarbonate

Question 69

Even at rest, most neurons have periodic production of action potentials, known as the:

A) spontaneous firing rate.
B) excitatory firing rate.
C) all-or-none law.
D) Dale's principle.

Question 70

An EPSP is to ____ as an IPSP is to ____.

A) hyperpolarization; depolarization
B) depolarization; hyperpolarization
C) spatial summation; temporal summation
D) temporal summation; spatial summation

Question 71

Which one of Sherrington's inferences about the synapse was WRONG?

A) Transmission at a synapse is slower than transmission of impulses along an axon.
B) Transmission at the synapse is primarily an electrical process.
C) Synapses can be either excitatory or inhibitory.
D) Synapses make spatial summation and temporal summation possible.

Question 72

An IPSP represents:

A) the location where a dendrite branches.
B) a gap in a myelin sheath.
C) a subthreshold depolarization.
D) a temporary hyperpolarization.

Question 73

Which of the following is TRUE about the spontaneous firing rates of neurons?

A) EPSPs increase the frequency.
B) EPSPs decrease the frequency.
C) IPSPs increase the frequency.
D) One EPSP equals the effect of two IPSPs.

Question 74

A temporary hyperpolarization is known as an:

A) EPSP.
B) IPSP.
C) ISPS.
D) EPIP.

Question 75

Which of the following is NOT a factor in determining whether or not two EPSPs combine to reach threshold?

A) size of the EPSPs
B) timing between them
C) threshold of the postsynaptic cell
D) threshold of the presynaptic cell

Question 76

Inhibitory synapses on a neuron:

A) hyperpolarize the postsynaptic cell.
B) weaken the cell's polarization.
C) increase the probability of an action potential.
D) move the potential closer to the cell's threshold.

Question 77

Increased permeability to ____ would most likely result in an IPSP.

A) sodium
B) potassium
C) calcium
D) bicarbonate

Question 78

A normal, healthy animal never contracts the flexor muscles and the extensor muscles of the same leg at the same time. Why not?

A) When the interneuron sends excitatory messages to one, inhibitory messages go to the other.
B) They are mechanically connected in a way that makes it impossible for both to contract at the same time.
C) Such coordination is learned through prenatal movement.
D) Both muscles are controlled by branches of the same axon.

Question 79

What was the first evidence reported by T. R. Elliott suggesting that synapses operate chemically?

A) Adrenaline mimics the effects of the parasympathetic nervous system.
B) Adrenaline decreases heart rate.
C) Adrenaline produces a hormone which decreases heart rate.
D) Adrenaline mimics the effects of the sympathetic nervous system.

Question 80

After one frog's heart has been stimulated, an extract of fluid from that heart can make a second frog's heart beat faster. What conclusion did Otto Loewi draw from these results?

A) Transmission at synapses is a chemical event.
B) The sympathetic and parasympathetic nervous systems are antagonistic.
C) Transmission at heart muscle synapses is electrical.
D) Hormones facilitate the actions of the nervous system.