Deck 3: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals

Question 1

Ion channels are made of

A) protein.
B) polysaccharide.
C) lipid.
D) carbohydrate.

Answer 1

A

Question 2

Ions are atoms or molecules that carry an electric charge due to the gain or loss of

A) protons.
B) electrons.
C) neutrons.
D) positrons.

Answer 2

B

Question 3

Refer to the figure.
The meter in this figure is located at the
a. synapse.
b. axon hillock.
c. dendrite.
d. axon terminal.

Answer 3

NO ANSWER

Question 4

In general, the action potential is first initiated at the

A) synapse.
B) outer reaches of the dendrite.
C) axon hillock.
D) node of Ranvier.

Question 5

Refer to the figure, which shows two voltage-gated Na⁺ channels (in blue) in the center.
What is taking place in this figure?

A) A depolarizing force is bringing the membrane closer to threshold.
B) The voltage-gated Na⁺ channels have opened, and action potential is triggered.
C) The open Na⁺ channels have created the resting potential.
D) The open Na⁺ channels have produced afterpotential.

Question 6

The substance tetrodotoxin (TTX), found in the ovaries of pufferfish, is useful for studying the ionic mechanisms of the neuron because it

A) selectively blocks sodium channels.
B) selectively blocks potassium channels.
C) prevents ion channels from closing.
D) directly stimulates neurons.

Question 7

The sodium-potassium pump is responsible for

A) pushing three sodium ions out of the cell for every two potassium ions pumped in.
B) initiating the action potential.
C) pumping potassium and sodium into the cell.
D) creating a positive net charge inside the cell.

Question 8

The giant axons of squids have been used in neurophysiological research because they attain diameters of _______ mm.

A) 0.5
B) 5
C) 50
D) 500

Question 9

The largest-diameter myelinated axons in mammals conduct action potentials at

A) 120 m/s.
B) 150 m/s.
C) 1 m/s.
D) 100 m/s.

Question 10

At the K⁺ equilibrium potential, the electrostatic pressure pulling K⁺ ions into the neuron is balanced by the concentration gradient pushing them out; at this point, the resting membrane potential is about _______.

A) -65 mV
B) -40 mV
C) +40 mV
D) +100 mV

Question 11

An afterpotential is

A) a brief hyperpolarization that follows an action potential ("undershoot").
B) a brief depolarization that follows an action potential ("overshoot").
C) a brief hyperpolarization that follows an EPSP ("undershoot").
D) the portion of an action potential between 0 and +30 mV.

Question 12

Inside the nerve cell there is a high concentration of _______ ions, while outside the cell there is a high concentration of _______ ions.

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

Question 13

Action potentials generally are not transmitted along dendrites because they have

A) sodium channels.
B) few voltage-gated Na⁺ channels.
C) no myelin.
D) mitochondria.

Question 14

A large fraction of the energy consumed by the brain is used for

A) producing action potentials.
B) synthesizing and releasing neurotransmitters.
C) saltatory conduction.
D) maintaining ionic differences across neuronal membranes.

Question 15

When applying hyperpolarizing or depolarizing stimulus to the membrane of a neuron, the beginning and end of the neuron's response become distorted. This is due to

A) conductance of the membrane.
B) the insulating properties of myelin.
C) capacitance of the membrane.
D) gated ion channels.

Question 16

In _______ clamping, the membrane potential of an axon is measured and manipulated; _______ clamping allows the manipulation and analysis of part of a membrane, even a single ion channel.

A) patch; ion
B) axon; voltage
C) threshold; electrode
D) voltage; patch

Question 17

The toxins TTX and STX both block _______ channels, preventing the production of _______.

A) sodium; electrostatic pressure
B) potassium; local potentials
C) sodium; action potentials
D) calcium; afterpotentials

Question 18

Myelin increases the speed of conduction because it

A) permits the flow of ionic current across the membrane.
B) resists the flow of current across the membrane.
C) releases special chemicals that aid conduction.
D) increases capacitance.

Question 19

The giant axons of some invertebrates conduct action potentials at speeds up to _______ m/s.

A) 5
B) 120
C) 20
D) 2

Question 20

The myelin sheath that encases some axons is interrupted by _______, small gaps spaced about every millimeter along the axon.

A) channelopathies
B) batrachotoxin spaces
C) nodes of Ranvier
D) ion channel openings

Question 21

The overall amplitude of the action potential is about

A) 70 mV.
B) -70 mV.
C) 100 mV.
D) 1 V.

Question 22

Inhibitory postsynaptic potentials differ from excitatory postsynaptic potentials most significantly in their

A) degree of capacitance.
B) direction of membrane polarization.
C) ease of elicitation.
D) overall amplitude.

Question 23

Most IPSPs are attributable to the

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

Question 24

Whether a synapse is excitatory or inhibitory is determined by the

A) number of action potentials arriving at the presynaptic axon terminal.
B) size of the calcium current flowing into the presynaptic axon terminal.
C) type of transmitter released by the presynaptic neuron and the receptor to which that transmitter binds on the postsynaptic neuron.
D) sensitivity of the postsynaptic membrane.

Question 25

Substances that bind to receptor proteins and change the permeability of ion channels are called

A) neuroregulators.
B) blockers.
C) transporters.
D) neurotransmitters.

Question 26

Refer to the figure.
This figure depicts the process of

A) an action potential propagating over a presynaptic membrane.
B) kiss and run.
C) transmitter reuptake.
D) exocytosis.

Question 27

_______ receptors recognize the synaptic transmitter, but they do not themselves contain any ion channels.

A) Metabotropic
B) Ionotropic
C) Ligand gated
D) Channel linked

Question 28

At chemical synapses, most of the synaptic delay (the time between the arrival of a presynaptic action potential and the appearance of a postsynaptic EPSP or IPSP) is attributable to the

A) the time needed for Ca²⁺ to enter the terminal and the vesicles to fuse.
B) rate of diffusion of neurotransmitter molecules across the synapse.
C) rate at which vesicles move to the presynaptic membrane and rupture.
D) interaction of the transmitter with its receptors.

Question 29

Which process is not involved in chemical synaptic transmission?

A) Electrical conduction across the synaptic cleft
B) Binding to autoreceptors
C) Influx of calcium at the presynaptic membrane
D) Reuptake

Question 30

The specialized presynaptic membrane receptors that remove molecules of transmitter from a synapse are called

A) translators.
B) transponders.
C) transporters.
D) ligand-gated channels.

Question 31

Most ACh receptors in the brain are

A) nicotinic.
B) muscarinic.
C) metabotropic.
D) unused.

Question 32

The nicotinic ACh receptor is made up of _______ protein subunits.

A) two
B) three
C) four
D) five

Question 33

The lock-and-key analogy is used to describe the

A) action of transmitter molecules on receptor proteins.
B) activation of the nerve impulse.
C) degradation of transmitter molecules by enzymes.
D) binding of G proteins to transmitter receptors.

Question 34

Muscarine and nicotine mimic the action of

A) G proteins.
B) calcium.
C) acetylcholine.
D) GABA.

Question 35

Acetylcholine receptors are thought to be in the same family as GABA, glycine, and glutamate receptors because they

A) bind the same neurotransmitters.
B) have a similar structure.
C) are found in the same neurons.
D) all cause inhibitory responses.

Question 36

The quantity of many types of receptors in the brain may vary during the day by

A) 1 to 2%.
B) 5%.
C) 50%.
D) 100%.

Question 37

A compensatory increase in receptor availability at the synapse of a neuron is called

A) antagonistic regulation.
B) agonist regulation.
C) up-regulation.
D) down-regulation.

Question 38

The neurotransmitter acetylcholine acts on at least _______ different types of receptors.

A) two
B) three
C) four
D) five

Question 39

Otto Loewi's experiments showed that the _______ releases acetylcholine, which _______.

A) heart; affects the vagus nerve
B) vagus nerve; increases heart rate
C) vagus nerve; decreases heart rate
D) brain; decreases heart rate

Question 40

Curare and bungarotoxin are similar in that they both

A) act on the GABA receptor.
B) act as acetylcholine receptor agonists.
C) come from animals.
D) act as acetylcholine receptor antagonists.

Question 41

The poison extracted from the mushroom Amanita muscaria is a(n)

A) GABA receptor agonist.
B) GABA receptor antagonist.
C) acetylcholine receptor antagonist.
D) acetylcholine receptor agonist.

Question 42

The chemical that Loewi initially called Vagusstoff turned out to be

A) acetylcholine.
B) muscarine.
C) GABA.
D) calcium.

Question 43

Which compound would prevent the release of neurotransmitters from stimulated neurons?

A) Bungarotoxin because it disables t-SNAREs.
B) Tetanus toxin because it cuts up SNARE proteins.
C) Synaptotagmin because it senses Ca²⁺.
D) Tetrodotoxin because it blocks exocytosis.

Question 44

G proteins are able to amplify the message from a single receptor because they

A) activate second messenger proteins inside the cell.
B) are a component of ionotropic receptors.
C) affect one ion channel.
D) are ligand-gated ion channels.

Question 45

_______ (reduction of the resting potential) of an axon until it reaches a threshold value opens voltage-gated sodium (Na⁺) channels, making the membrane completely _______ to sodium ions (Na⁺). The Na⁺ ions rush in, and the axon becomes briefly more positive inside than outside. This event is called an _______.

A) Depolarization; permeable; action potential
B) Upregulation; impermeable; action potential
C) Up-polarization; permeable; adverse reaction
D) Deregulation; impermeable; adverse reaction

Question 46

_______ conduction of the action potential along the nodes of _______ between myelin sheaths speeds propagation down the axon.

A) Saltatory; Ranvier
B) Saltatory; Loewi
C) Sodium; Ranvier
D) Sodium; Loewi

Question 47

Neurons process information by integrating (summing algebraically) the postsynaptic potentials through both _______ summation (summing potentials from different locations) and _______ summation (summing potentials across time).

A) temporal; spatial
B) spectral; temporal
C) spatial; temporal
D) spectral; chemical

Question 48

Different concentrations of ions inside and outside the neuron, especially _______ ions to which the resting membrane is selectively permeable, account for the resting membrane potential.

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

Question 49

Action potentials are initiated just past the _______ when the excess of EPSPs over IPSPs reaches threshold.

A) Nodes of Ranvier
B) dendritic branches
C) axon hillock
D) myelin sheath

Question 50

During the action potential, the neuron cannot be excited by a second stimulus; it is _______. For a few milliseconds afterward, the hyperpolarized neuron is _______, requiring a stronger stimulation than usual in order to fire.

A) hyperpolarized refractory; relatively refractory
B) hyperpolarized; absolutely refractory
C) relatively refractory; hyperpolarized
D) absolutely refractory; relatively refractory

Question 51

_______ synapses work with practically no time delay, whereas _______ synapses have a delay on the order of about a millisecond.

A) Electrical; chemical
B) Axo-dendritic; axo-somatic
C) Axo-somatic; axo-axonic
D) Retrograde; electrical

Question 52

A ligand is a

A) specific type of drug.
B) type of electrical stimulus.
C) cholinergic synapse.
D) molecule that binds to receptor proteins.

Question 53

Bungarotoxin is derived from a type of

A) mushroom.
B) snake.
C) spider.
D) plant.

Question 54

Muscarine is derived from a type of

A) mushroom.
B) snake.
C) spider.
D) plant.

Question 55

At metabotropic synapses, second messengers are activated in postsynaptic neurons by

A) electrical currents.
B) specific enzymes.
C) mitochondria.
D) transmitter-receptor combinations.

Question 56

Directly controlled ion channels are

A) slow and metabotropic.
B) slow and ionotropic.
C) fast and metabotropic.
D) fast and ionotropic.

Question 57

What percentage of the known transmitters and hormones activates cellular mechanisms through receptors coupled to G proteins?

A) Less than 5%
B) 20%
C) 50%
D) 80%

Question 58

Refer to the figure.
This diagram illustrates

A) ectopic transmission.
B) an electrical synapse.
C) a nondirected synapse.
D) an axo-axonic synapse.

Question 59

Which statement about retrograde synapses is false?

A) The postsynaptic cell releases a gas neurotransmitter.
B) Transmission starts with classic axo-dendritic activity.
C) The presynaptic cell is signaled to release more transmitter.
D) They typically involve dendro-dendritic activity.

Question 60

When a transmitter binds to a metabotropic receptor that is coupled to a G protein, a subunit of the G protein

A) either closes a nearby ion channel or triggers other biochemical reactions in the postsynaptic cell.
B) degrades.
C) binds to a transmitter receptor.
D) either opens up a nearby ion channel or triggers other biochemical reactions in the postsynaptic cell.

Question 61

The phenomenon of convergence is illustrated by the circuits of the visual system, in which about 100 million receptor cells send information to about _______ ganglion cells.

A) 100,000
B) 1 million
C) 100 million
D) 1 billion

Question 62

A stretch of the patellar tendon activates

A) the flexion reflex.
B) an oscillator circuit.
C) the knee-jerk reflex.
D) the jaw-jerk reflex.

Question 63

The simplest neural circuit is the

A) oscillator circuit.
B) feedback circuit.
C) neural chain.
D) amplifier circuit.

Question 64

In the knee-jerk reflex, the total time between the stimulus and the initiation of the response is about _______ ms.

A) 10
B) 40
C) 100
D) 400

Question 65

The phenomenon of divergence is illustrated by the visual system, in which 1 million axons of the optic nerve communicate with _______ neurons in the cerebral cortex.

A) a thousand
B) half a million
C) 500 million
D) over a billion

Question 66

The term "kindling" refers to

A) the experimental induction of seizures using subthreshold stimuli.
B) an experimental procedure for blocking the spread of seizures.
C) the application of massive depolarizing stimuli to a brain region.
D) the net effect of integrating postsynaptic potentials at the axon hillock.

Question 67

The alternating muscular jerks and relaxations that accompany some seizures are characteristic of the _______ phase.

A) tonic
B) clonic
C) petit mal
D) recovery

Question 68

Spontaneous electrical rhythms that can be recorded from the surface of the scalp

A) indicate a pathological condition, such as epilepsy.
B) demonstrate that neurons are constantly moving.
C) are generated by the activity of populations of neurons.
D) reflect the brain's reaction to discrete stimuli.

Question 69

_______ reflect complex information processing.

A) Short-latency auditory-evoked potentials
B) Long-latency ERP components
C) Changes in potential amplitude due to stimulus strength
D) "Rebound" potentials

Question 70

The short-latency components of event-related potentials appear to be influenced primarily by

A) cognitive processing.
B) endogenous factors.
C) exogenous factors.
D) cortical responses.

Question 71

In optogenetics, researchers use _______ light to stimulate _______.

A) yellow; channelrhodopsin
B) red; halorhodopsin
C) blue; halorhodopsin
D) blue; channelrhodopsin

Question 72

In an animal research study, channelrhodopsin is inserted into neurons that make GABA (which inhibits neurons), and halorhodopsin is inserted into neurons that make glutamate (which excites neurons). Both sets of neurons make connections with a set of neurons responsible for eye blinking. If the eye-blink neurons are stimulated by blue light, the animal will _______ because the _______ neurons will be _______.

A) blink; glutamate; depolarized
B) not blink; GABA; depolarized
C) not blink; glutamate; hyperpolarized
D) blink; GABA; hyperpolarized

Question 73

Halorhodopsin is stimulated by _______ light and allows _______ ions to enter the cell.

A) yellow; sodium
B) blue; sodium
C) blue; chloride
D) yellow; chloride

Question 74

The size of an action potential is independent of the stimulus magnitude, a phenomenon that is referred to as the _______ property of action potentials.

Question 75

The _______ are regularly spaced along the length of myelinated axons.

Question 76

The _______ is the site at which the action potential is initiated.

Question 77

The generation of the action potential depends on _______ channels, which are opened through a process of regenerative depolarization.

Question 78

The electrical potential across a semipermeable membrane separating different concentrations of ions is most accurately predicted by the _______ equation.

Question 79

Inhibitory postsynaptic potentials are characterized by _______ of the postsynaptic membrane.

Question 80

The enzyme _______ breaks down molecules of the neurotransmitter acetylcholine, stopping its action at synapses.