Deck 4: How Do Neurons Use Electrical Signals to Transmit Information 

Question 1

The technique of electrical stimulation was first discovered by:

A)Luigi Galvani.
B)René Descartes.
C)Gustave Fritsch and Edward Hitzig.
D)David Ferrier.

Answer 1

A

Question 2

In 1874, the physician Roberts Bartholow directly stimulated a _____ brain with electricity.

A)dog
B)rabbit
C)human
D)cat

Answer 2

C

Question 3

To measure the voltage across the cell membrane, you would normally:

A)insert two electrodes into the axon and measure the voltage difference.
B)place one electrode on the outer surface of an axon's membrane and another inside the axon and measure the voltage difference.
C)place two electrodes on the outer surface of the axon's membrane and measure the voltage difference.
D)All of the answers are correct.

Answer 3

B

Question 4

Recording from single neurons was made possible by the invention of:

A)the electroencephalogram and the voltmeter.
B)the oscilloscope and the voltmeter.
C)the EEG and the microelectrode.
D)the oscilloscope and the microelectrode.

Question 5

Nineteenth-century scientists Fritsch and Hitzig discovered that electrical stimulation of the neocortex leads to:

A)hearing sounds.
B)movements.
C)seizures.
D)seeing patterns.

Question 6

The volt is a unit of:

A)electrical potential.
B)current flow.
C)electrical activity.
D)motion of electric charge.

Question 7

René Descartes believed that _____ carried signals through the nervous system.

A)neurons
B)phlegm
C)the pineal gland
D)cerebrospinal fluid

Question 8

Erica is an 18-year-old in her first year of university. One day while she was watching a video in class, Erica started to hear what she thought was music playing. Suddenly, she began shaking in her seat and fell to the floor. After the incident ended, one of her classmates helped her to the campus medical center, where she was later diagnosed as having:

A)Huntington disease.
B)Parkinson disease.
C)epilepsy.
D)myasthenia gravis.

Question 9

Electricity is a flow of electrons from a body that contains a higher charge (more electrons) to a body that has a lower charge (fewer electrons). The body containing the higher electrical charge is called a:

A)positive pole.
B)negative pole.
C)dipole.
D)ground pole.

Question 10

Microelectrodes can:

A)be made from glass.
B)be made from wire.
C)have a tip as small as 0.001 millimeter.
D)All of the answers are correct.

Question 11

Because the giant axons of the squid are nearly _____ in diameter, they were used to record electrical activity in neurons for the first time.

A)1 centimeter
B)1 millimeter
C)5 millimeters
D)0.1 millimeter

Question 12

How does a squid benefit from having unusually large axons?

A)They enable the squid to perform complex grasping behavior with its tentacles.
B)They enable the squid to jet-propel away from predators.
C)They boost the squid's immune system.
D)They enhance the squid's fertility.

Question 13

Which of the following treatments is (are) used to help reduce epilepsy?

A)medication
B)deep brain stimulation
C)a high-fat, low-carbohydrate diet
D)All of the answers are correct.

Question 14

_____ is a neurological disorder that is linked to periods of excessive neural synchrony.

A)Epilepsy
B)Parkinson disease
C)Multiple sclerosis
D)Stroke

Question 15

Neurons in most animals, including humans, are approximately _____ micrometers in diameter.

A)1 to 20
B)0.01 to 0.2
C)100 to 200
D)up to 1

Question 16

An electroencephalogram, or EEG, can theoretically be recorded by:

A)a voltmeter.
B)a current meter.
C)an amp meter.
D)either a voltmeter or a current meter.

Question 17

The patch technique involves:

A)placing the tip of a microelectrode on an axon.
B)recording between two microelectrodes, one inside the axon and the other outside.
C)placing the tip of the microelectrode in an axon and applying some back suction.
D)placing the tips of two microelectrodes in an axon and recording between them.

Question 18

When Richard Caton first measured fluctuations on a voltmeter from electrodes placed on the scalp of a human subject, he was recording what we now call:

A)an electroencephalogram.
B)the action potential.
C)a magnetoencephalogram.
D)axonal conductance.

Question 19

_____ won the Nobel Prize in 1963 for being the first to describe the electrical activity of neurons.

A)Young
B)von Helmholtz
C)Hodgkin and Huxley
D)Watson and Crick

Question 20

The speed of information flow in a nerve was first measured by:

A)Hermann von Helmholtz.
B)Wilder Penfield.
C)Eduard Hitzig.
D)Gustave Fritsch.

Question 21

A change in the resting potential from -70 mV to -65 mV is called:

A)depolarization.
B)hyperpolarization.
C)graded excitatory potential.
D)nothing, as these changes occur spontaneously.

Question 22

Which of the following is NOT true?

A)The cell membrane is semipermeable, so it keeps in large negatively charged protein molecules.
B)The membrane keeps out Na⁺ and allows K⁺ and Cl^- to pass more freely.
C)The membrane has a sodium-potassium pump that removes potassium from inside the cell and replaces it with sodium.
D)The summed charges of the unequally distributed ions leave the inside of the membrane at -70 mV relative to the outside.This is the cell's resting potential.

Question 23

The difference in charge between two regions is referred to as:

A)a concentration gradient.
B)a voltage gradient.
C)diffusion.
D)current flow.

Question 24

The negative charge inside the cell membrane is largely a product of the presence of negatively charged:

A)potassium ions.
B)sodium ions.
C)protein anions.
D)All of the answers are correct.

Question 25

When a substance moves from an area of high concentration to an area of low concentration, it is an example of a(n):

A)concentration gradient.
B)voltage gradient.
C)ionic translocation.
D)None of the answers is correct.

Question 26

When the neuron is at rest, _____ channels are normally closed, whereas _____ is free to enter and leave the cell.

A)K⁺; Na⁺
B)Cl^-; Na⁺
C)Na⁺; K⁺
D)K⁺; Cl^-

Question 27

If a small amount of dye is placed in a beaker of water, it will flow away from the initial point of contact. The ensuing process illustrates:

A)diffusion.
B)concentration.
C)charge.
D)electrostatic pressure.

Question 28

A change in the resting potential from -70 mV to -73 mV is called:

A)depolarization.
B)hyperpolarization.
C)graded excitatory potential.
D)nothing, as these changes occur spontaneously.

Question 29

Positively charged ions are called _____, while negatively charged ions are called _____.

A)proteins; anions
B)anions; cations
C)cations; anions
D)axons; neurons

Question 30

The movement of ions from an area of high concentration to an area of low concentration through random motion is called:

A)a concentration gradient.
B)a voltage gradient.
C)diffusion.
D)ionic translocation.

Question 31

At rest, the concentrations of _____ are higher inside of a neuron, whereas the concentrations of _____ are higher outside of a neuron.

A)potassium (K⁺); sodium (Na⁺)
B)sodium (Na⁺); potassium (K⁺)
C)potassium (K⁺); chloride (Cl^-)
D)potassium (K⁺); anions (A^-)

Question 32

Resting potential is a store of potential _____ produced by a greater _____ charge on the intracellular side relative to the extracellular side.

A)energy; positive
B)energy; negative
C)ions; negative
D)extracellular fluid; positive

Question 33

The resting potential of the inside of an axon, relative to the outside:

A)is -70 mV in all species.
B)is -90 mV in all species
C)can vary from -40 mV to -90 mV within a species.
D)can vary from -40 mV to -90 mV between species.

Question 34

The neuronal membrane is:

A)fully permeable.
B)permeable only to ions.
C)permeable only to neutral molecules.
D)permeable to some ions but not others.

Question 35

The basis of electrical activity in nerves is the:

A)movement of intracellular and extracellular ions.
B)movement of extracellular fluid.
C)equilibrium between intracellular and extracellular ions.
D)elongation and contraction of axons.

Question 36

Channels in the cell membrane are formed by:

A)sodium ions.
B)potassium ions.
C)protein molecules.
D)lipids.

Question 37

Large protein anions are:

A)manufactured by glial cells.
B)manufactured within a neuron.
C)transported to a neuron by glial cells.
D)not part of a neuron.

Question 38

There are approximately _____ as many K⁺ ions inside a cell as outside it.

A)20 times
B)2 times
C)one-tenth
D)half

Question 39

Which of the following is NOT involved in producing the resting potential?

A)potassium ions
B)chloride ions
C)calcium ions
D)sodium ions

Question 40

The sodium-potassium pump _____ exchanges three _____ for two _____.

A)continuously; intracellular Na⁺; extracellular K⁺.
B)continuously; intracellular K⁺; extracellular Na⁺.
C)continuously; extracellular Na⁺; intracellular K⁺.
D)intermittently; intracellular K⁺; extracellular Na⁺.

Question 41

Voltage-sensitive sodium channels are active:

A)whenever the cell membrane starts to depolarize.
B)when the voltage across the membrane reaches zero.
C)when the threshold voltage of the cell is reached.
D)when the voltage across the membrane reaches +30 mV.

Question 42

Na⁺ and K⁺ channels on axons are:

A)mainly neurotransmitter dependent.
B)mainly voltage dependent.
C)mainly calcium dependent.
D)both neurotransmitter and voltage dependent.

Question 43

During an action potential, the voltage of the cell membrane:

A)drops to zero and then returns to -70 mV.
B)drops to zero, returns to about -100 mV, and then goes to 70 mV.
C)goes to about +30 mV and then drops to -70 mV.
D)goes to about +30 mV, drops to -100 mV, and then goes to -70 mV.

Question 44

Refractory periods are due to:

A)voltage-sensitive sodium and potassium channels.
B)voltage-sensitive chloride channels.
C)the time constraint on the sodium-potassium pump.
D)inhibitory postsynaptic potentials.

Question 45

Which of the following channels does NOT underlie graded potentials?

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

Question 46

_____ channels are more sensitive than _____ channels, so they open first during the action potential.

A)Calcium; potassium
B)Potassium; calcium
C)Sodium; potassium
D)All channels are equally sensitive.

Question 47

The action potential normally consists of the summed current changes caused by the _____ and the _____.

A)inflow of sodium; outflow of potassium
B)outflow of sodium; inflow of potassium
C)inflow of calcium; outflow of potassium
D)inflow of sodium; outflow of chloride

Question 48

Tetrodotoxin (puffer fish poison) mainly influences the role of:

A)potassium channels in hyperpolarization.
B)sodium channels in depolarization.
C)potassium channels in depolarization.
D)sodium channels in hyperpolarization.

Question 49

Small voltage fluctuations in the cell membrane that occur in the vicinity of the axon are called:

A)action potentials.
B)graded potentials.
C)ion fluctuations.
D)nerve impulses.

Question 50

The magnitude of an action potential (AP) is measured near the axon hillock using an electrode and then measured again 2 mm farther down the axon. Compared to the AP measured near the axon hillock, the AP 2 mm farther down the axon is:

A)larger.
B)smaller.
C)of the same magnitude.
D)completely nullified.

Question 51

The voltage of a neural membrane that is sufficient to cause an action potential is approximately _____; it is called a _____.

A)-70 mV; resting potential
B)-50 mV; graded potential
C)-65 mV; threshold potential
D)-50 mV; threshold potential

Question 52

A change in the resting potential from -70 mV to -50 mV typically results in:

A)an excitatory postsynaptic potential.
B)repolarization.
C)an action potential.
D)hyperpolarization.

Question 53

The repolarization of the neuronal membrane is largely due to the:

A)closing of calcium channels, stopping the influx of calcium.
B)opening of potassium channels, allowing the outflow of potassium.
C)closing of potassium channels, stopping the influx of potassium.
D)closing of sodium channels, stopping the outflow of sodium.

Question 54

Sodium channels close when the membrane potential reaches approximately:

A)+50 mV.
B)+30 mV.
C)-50 mV.
D)0 mV.

Question 55

_____ channels are less sensitive than _____ channels, so during an action potential, they open more slowly but remain open longer.

A)Calcium; sodium
B)Sodium; potassium
C)Chloride; sodium
D)Potassium; sodium

Question 56

A cell cannot produce an action potential:

A)during the relatively refractory period.
B)during the absolutely refractory period.
C)during the intermediate refractory period.
D)None of the answers is correct.

Question 57

Tetraethylammonium (TEA):

A)blocks potassium channels.
B)blocks sodium channels.
C)blocks chlorine channels.
D)neutralizes large protein molecules.

Question 58

A(n) _____ channel only opens or closes at specific membrane voltages.

A)nerve impulse
B)voltage-activated
C)absolutely refractory
D)relatively refractory

Question 59

An action potential is:

A)a large graded potential.
B)a large, brief reversal in the polarity of a membrane.
C)the same as a threshold potential.
D)seldom shorter than 10 milliseconds.

Question 60

Depolarization is primarily linked with _____, whereas hyperpolarization is mainly linked with _____.

A)sodium; calcium
B)potassium; sodium
C)sodium; chloride
D)chloride; potassium

Question 61

Nerve impulse describes:

A)an action potential crossing the synaptic cleft.
B)input at the dendrites of a cell.
C)the movement of an action potential along the axon.
D)an action potential along the combined axons, which are called nerves.

Question 62

The speed at which nerve impulses travel down an axon are greatly increased by:

A)myelin.
B)refractory periods.
C)the length of the axon.
D)calcium channels.

Question 63

Which of the following is NOT one of the important reasons for refractory periods in neurons?

A)They limit the firing rate of the neuron.
B)They force nerve impulses to travel in one direction.
C)They increase the sensitivity of the neuron.
D)They allow time for the neuron to reset prior to another action potential.

Question 64

The symptoms of multiple sclerosis are caused by:

A)excess myelin on axons.
B)loss of myelin around axons.
C)excess excitatory input.
D)excess inhibitory input.

Question 65

Myelin is important for propagating action potential (AP) because:

A)it increases the AP's conduction speed.
B)it reduces the need for sodium and potassium.
C)it conserves energy.
D)it both increases the AP's conduction speed and conserves energy.

Question 66

Multiple sclerosis is thought to be:

A)an autoimmune disease.
B)related to vitamin D.
C)related to genetic risk factors.
D)All of the answers are correct.

Question 67

Autoimmune diseases are illnesses resulting from:

A)the inability of the immune system to fight off harmful substances in the body.
B)the degeneration of the immune system.
C)the production of too many antibodies when fighting off an outside infection.
D)the body attacking substances and tissues that are normally present in the body.

Question 68

Myelination of axons in humans makes up for the _____ in our nervous system.

A)small axons
B)large axons
C)lack of Schwann cells
D)large nodes of Ranvier

Question 69

A brief hyperpolarization of the neuronal membrane that makes it less likely that the neuron will fire an action potential is called:

A)saltatory conduction.
B)an inhibitory postsynaptic potential (IPSP).
C)an excitatory postsynaptic potential (EPSP).
D)spatial summation.

Question 70

A brief depolarization of the neuronal membrane that makes it more likely that the neuron will fire an action potential is called:

A)saltatory conduction.
B)an inhibitory postsynaptic potential (IPSP).
C)an excitatory postsynaptic potential (EPSP).
D)spatial summation.

Question 71

Saltatory conduction is aided by _____ located at the _____.

A)sodium-potassium pumps; terminal buttons
B)sodium and potassium channels; nodes of Ranvier
C)calcium channels; nodes of Ranvier
D)glial cells; nodes of Ranvier

Question 72

Melissa, a 23-year-old woman, has been having tingling sensations in her right arm and leg for a few weeks. Today, when she woke up, she realized that she could barely move her right arm. She had a similar set of symptoms a couple of years ago, but they went away, so she thought everything was fine. Your advice to Melissa is to go to the doctor because she may have:

A)the flu.
B)a brain tumor.
C)multiple sclerosis.
D)Huntington disease.

Question 73

Which technology is used to observe the plaque that forms at sites of myelin loss in patients suffering from multiple sclerosis?

A)ultrasound
B)optogenetics
C)magnetic resonance imaging (MRI)
D)computer tomography (CT scan)

Question 74

The domino effect best describes the:

A)absolutely refractory period.
B)nerve impulse.
C)relatively refractory period.
D)resting membrane potential.

Question 75

Because of refractory periods, the maximum firing rate of a neuron is approximately _____ impulses per second.

A)500
B)1000
C)100
D)200

Question 76

On larger myelinated axons, nerve impulses can reach speeds of up to _____ meters per second.

A)100
B)50
C)120
D)30

Question 77

An action potential usually goes only in one direction in an axon because:

A)the ions can flow only in one direction.
B)the refractory periods force the impulse to go in one direction.
C)the ion flow is attracted to chemicals in the synaptic knob.
D)autoreceptors inhibit backward flow of ions.

Question 78

The propagation of the nerve impulse is:

A)not decremental.
B)related to the opening of potassium and sodium ion channels.
C)similar to the effect of falling dominoes.
D)All of the answers are correct.

Question 79

_____ produce(s) myelin in the peripheral nervous system, whereas _____ produce(s) myelin in the central nervous system.

A)Ependymal cells; Schwann cells
B)Astroglia; oligodendroglia
C)Oligodendroglia; Schwann cells
D)Schwann cells, oligodendroglia

Question 80

Saltatory conduction refers to:

A)sodium concentration in the extracellular fluid.
B)action potentials that are facilitated by sodium.
C)action potentials jumping from one node to the next.
D)the leakage of the sodium channels that require the existence of a sodium-potassium pump.