Deck 32: Neuroscience I: Structure, Function, and Evolution of Nervous Systems

Question 1

Compare the leakage rates of sodium and potassium into and out of a neuron at rest.How is the relationship between these rates best described?

A)Leakage of sodium ions out of the neuron is greater than leakage of potassium ions into the neuron.
B)Leakage of sodium ions into the neuron is greater than leakage of potassium ions out of the neuron.
C)Leakage of potassium ions out of the neuron is greater than leakage of sodium ions into the neuron.
D)Leakage of potassium ions into the neuron is greater than leakage of sodium ions out of the neuron.
E)Leakage of potassium ions out of the neuron is equivalent to leakage of sodium ions into the neuron.

Answer 1

C

Question 2

When the cell is NOT sending signals,the electrical difference between the inside and outside of a neuronal membrane is specifically referred to as the

A)action potential.
B)graded potential.
C)resting potential.
D)membrane potential.
E)reversal potential.

Answer 2

C

Question 3

Multiple sclerosis (MS)is a progressive inflammatory disease of the central nervous system characterized by intermittent damage to myelin (called demyelination)caused by the destruction of specialized cells (oligodendrocytes)that form the substance.

Answer 3

Given what you know about the function of myelin,predict the consequences associated with its progressive loss.
__X__ Sensory abnormalities (e.g. ,tingling,numbness,itching,tightness,burning,shooting pain)and motor coordination loss.
_____ Racing heartbeat,hyperactivity and nausea.
_____ Low levels of potassium in the blood (hypokalemia).
__X__ Balance and equilibrium abnormalities (e.g. ,dizziness,vertigo,uncoordinated movements,tremor).

Question 4

What explanation can you give for why the sodium-potassium pump does not run out of ions to move in or out of the cell?

A)Leak channels are always open,allowing the passage of sodium ions (Na⁺)and potassium ions (K⁺)across the membrane.
B)The cell continuously produces more ions to replace those moved by the pump,maintaining a constant supply.
C)Many of the ions moved in or out then diffuse passively back through the membrane in the opposite direction.

Question 5

The differences in relative concentrations of ions inside and outside the cell act as an electrical force.The specific ion(s)MOST important to establishing the resting potential in neurons would be

A)Na⁺.
B)K⁺.
C)intracellular anions (e.g. ,proteins).
D)H⁺.
E)Na⁺,K⁺ and intracellular anions are all important.

Question 6

Duct tape is to its cardboard roll as the myelin sheath is to the

A)dendrite.
B)axon.
C)soma.
D)interneuron.

Question 7

In a neuron at rest,the membrane is most permeable to

A)potassium.
B)sodium.
C)chloride.
D)calcium.
E)magnesium.

Question 8

The two broad classes of cells in the nervous system include
1) )those responsible for information processing,and
2) )those providing mechanical and metabolic support.
These two categories of specialized cells are called

A)microglia and Schwann cells.
B)neurons and glial cells.
C)Schwann cells and glial cells.
D)neurons and fibrocytes.
E)astrocytes and Schwann cells.

Question 9

Interneurons are responsible for the distribution of sensory information and the coordination of motor activity.They are also involved with all higher functions,such as memory,planning,and learning.The more complex the response to a given stimulus,the greater the number of interneurons involved.Knowing this,what can you predict about the ratio of interneurons to sensory and motor neurons in the nervous system of higher animals?

A)There must be equal numbers of sensory neurons,motor neurons and interneurons.
B)Since interneurons connect the other two types,it is necessary to have only half as many interneurons as motor and sensory neurons.
C)Interneurons likely outnumber all other types of neurons combined.
D)None of these choices are correct.

Question 10

Scientists used microelectrodes to measure the resting membrane potential (inside relative to outside)of a typical neuron and discovered a difference of

A)70 mV.
B)300 mV.
C)-300 mV.
D)0 mV.
E)-70 mV.

Question 11

At rest,neurons exhibit a negative membrane potential.Among the factors that maintain this polarity,assess which is most DIRECTLY responsible for the difference between intracellular and extracellular ion concentrations?

A)movements of negatively charged proteins and nucleic acids across the membrane.
B)passive leakage of Na⁺ ions across the membrane.
C)passive leakage of K⁺ ions across the membrane.
D)movement of Na⁺ ions through voltage-gated Na⁺ channels.
E)movement of K⁺ ions through voltage-gated K⁺ channels.

Question 12

The electrical difference across a neuronal membrane is measured in

A)newtons.
B)milliwatts.
C)milliamperes.
D)joules.
E)millivolts.

Question 13

If you touch a hot stove and burn your hand,the pain isn't actually in your hand-it's in your head.What evidence can you provide to substantiate this claim?

A)Interneurons form connections directly from the burned receptor molecules to the brain.
B)Motor neurons pull your hand away from the flame,signaling pain to the brain.
C)Sensory neurons and interneurons carry the heat sensation to the brain where it is interpreted as painful.
D)A reflex arc allows the quick response between the hand and the brain;no interpretation occurs.

Question 14

In a reflex arc,the correct sequence of cell types through which an electrical signal would pass would be

A)motor neuron $\rarr$ sensory neuron $\rarr$ interneuron in the PNS
B)sensory neuron $\rarr$ motor neuron $\rarr$ interneuron in the CNS
C)motor neuron $\rarr$ interneuron in the PNS $\rarr$ sensory neuron
D)sensory neuron $\rarr$ interneuron in the CNS $\rarr$ motor neuron

Question 15

The part of the axon closest to the cell body is the

A)hillock.
B)dendrite.
C)soma.
D)myelin sheath.
E)nucleus.

Question 16

You are out at night and hear a sound in the bushes.The electrical signal carrying this information to your brain is carried first by a

A)sensory neuron.
B)motor neuron.
C)interneuron.
D)glial cell.
E)All of these choices are correct.

Question 17

The critical function of the sodium-potassium pump of neurons is to move

A)Na⁺ and K⁺ into the cell.
B)Na⁺ and K⁺ out of the cell.
C)Na⁺ into the cell and K⁺ out of the cell.
D)Na⁺ out of the cell and K⁺ into the cell.
E)Na⁺ and K⁺ into the cell and H⁺ out of the cell through an antiport mechanism.

Question 18

What type of neuron is responsible for carrying electrical signals AWAY from the CNS to elicit a response in the body?

A)sensory neuron
B)motor neuron
C)interneuron
D)glial cell
E)All of these choices are correct.

Question 19

Assess the merits of each action potential analogy;select the representation that corresponds most accurately.

A)An action potential happens like a ripple in a pond;a ripple spreads out and gets slightly weaker as it travels.
B)An action potential happens like a row of dominoes falling;the signal has constant velocity and constant strength no matter how long the row of dominoes may be.
C)An action potential happens like a crowd doing the wave in a football stadium;the enthusiasm and volume increase as more people get involved.

Question 20

The electrochemical gradient that determines how a charged ion will move through a permeable membrane depends upon

A)the electrical forces acting on that ion.
B)the difference in concentration of that ion on either side of the membrane.
C)the ratio between the charge on the ion and its atomic mass.
D)the combined effects of electrical forces and concentration differences across the membrane.
E)All of the choices for this question are correct.

Question 21

Synaptic vesicles discharge their contents by exocytosis at the

A)dendrite.
B)axon hillock.
C)nodes of Ranvier.
D)postsynaptic membrane.
E)presynaptic membranE.

Question 22

Complete the Nernst Equation by deciding what symbol belongs in the first blank.
_________ = 60 mV log₁₀ ([X_{extracellular}/X_{intracellular}]).

A)the equilibrium potential
B)the membrane potential
C)the action potential
D)resting potential
E)refractory potential

Question 23

If you applied a toxin that blocked non-voltage-gated potassium channels (i.e. ,the potassium "leak channels")in a resting neuron,it would cause the membrane potential to be

A)less negative.
B)more negative.
C)No change would be observed.

Question 24

After an action potential is triggered,the rapid increase in membrane potential can be attributed to

A)the direction reversal of the sodium/potassium pump.
B)the closing of sodium leak channels.
C)the opening of the activation gates of voltage-gated sodium channels.
D)the closing of potassium leak channels.
E)the opening of the voltage-gated potassium channels.

Question 25

It is accurate to say that neural transmission across nearly all mammalian synaptic clefts is the result of

A)neural impulses involving the flow of K⁺ and Na⁺ across the cleft.
B)neural impulses traveling across the gap as electrical currents.
C)neural impulses causing the release of chemicals that diffuse across the cleft.
D)neural impulses traveling across the cleft in both directions.
E)the calcium within the axons and dendrites of nerves adjacent to a synapse acting as the neurotransmitter.

Question 26

Identify the point in time during an action potential when a positive feedback process is occurring in a neuron.

A)when the neuron is at rest
B)as the neuron is being depolarized and passes the threshold potential
C)after the peak depolarization of the action potential when it is rapidly repolarizing
D)during the undershoot phase when the neuron is slightly hyperpolarized relative to the resting potential
E)A positive feedback process is occurring at all the time points given.

Question 27

Propose a valid reason to explain why is it critical that the K⁺ channel activation gate responds slightly slower to depolarization than the Na⁺ channel activation gate.

A)If both gates showed identical response times,movements of Na⁺ and K⁺ ions would cancel out each other's effects on membrane potential changes.
B)If both gates showed identical response times,movements of Na⁺ and K⁺ ions would magnify each other's effects on membrane potential changes,creating dangerously large action potentials.
C)It is not critical and there would be no change in action potential characteristics if this difference in response time did not exist.
D)The conformational change in one gate is necessary to trigger the activation of the other.

Question 28

Predict the expected consequence(s)of applying a toxin that blocks voltage-gated Ca²⁺ channels in a neuron.

A)No resting membrane potential would be observed (i.e. ,measures at 0 mV).
B)A rapid increase in membrane potential at threshold voltage would not occur.
C)Membrane potential would increase rapidly to peak with an action potential,but would not decrease immediately afterwards.
D)The neuron would become hyperpolarizeD.
E)Neuron conducts action potentials normally,but would not transmit these potentials across chemical synapses.

Question 29

When a neuron undergoes a change in membrane potential that is proportional to (i.e. ,varies depending on)the strength of the stimulus given to that neuron,this is referred to as a/an

A)equilibrium potential.
B)action potential.
C)resting potential.
D)reversal potential.
E)graded potential.

Question 30

The synaptic cleft is most accurately described as

A)a deep furrow in a postsynaptic cell where signals are received.
B)specialized channels in the presynaptic membrane that allow the passage of ions.
C)the narrow extracellular space between the presynaptic and postsynaptic neurons at the synapse.
D)recesses in the postsynaptic neuron membrane where neurotransmitters binD.
E)the area of neuronal membrane between the dendrites and the axon hillock.

Question 31

The period following an action potential during which a neuron cannot be stimulated to generate another action potential is referred to as

A)the refractory period.
B)the threshold period.
C)the resting period.
D)the inactivation perioD.
E)the critical period.

Question 32

Increasing the flow of Na⁺ ions into a neuron at rest (-70 mV initially)would trigger

A)hyperpolarization.
B)depolarization.
C)repolarization.
D)active transport.
E)None of the choices are correct.

Question 33

Identify the key feature of the action potential that ensures it will travel only one direction.

A)the activation state of the voltage-gated Na⁺ channel
B)the inactivation state of the voltage-gated Na⁺ channel
C)the activation state of the voltage-gated K⁺ channel
D)the inactivation state of the voltage-gated K⁺ channel
E)the temporary cessation in activity of the Na⁺/K⁺ pump

Question 34

The ion that increases its intracellular concentration in order to trigger the release of neurotransmitters is _____.

A)Ca²⁺
B)Mg²⁺
C)HCO₃^-
D)K⁺
E)Cl^-

Question 35

The level of depolarization at which an action potential will be triggered is referred to as the

A)resting potential.
B)membrane potential.
C)cationic potential.
D)refractory potential.
E)threshold potential.

Question 36

An excitatory neurotransmitter will produce an ______ that will ____ the postsynaptic neuron.

A)EPSP,depolarize
B)EPSP,hyperpolarize
C)IPSP,depolarize
D)IPSP,hyperpolarize
E)IPSP,not affect

Question 37

Graded potentials are particularly important for conveying stimulus intensity in

A)sensory neurons.
B)motor neurons.
C)interneurons.
D)skeletal muscle cells.
E)Schwann cells.

Question 38

Pufferfish (Fugu)are a delicacy in Japan,but must be cleaned very carefully as their liver contains tetrodotoxin which blocks voltage-gated Na⁺ channels.Imagine you are testing for the presence of this toxin using a neuron in a dish.You apply an electrical stimulus to the neuron that should produce an action potential.What will you observe if tetrodotoxin levels are high enough to block the neuron's voltage-gated Na⁺ channels?

A)The neuron will exhibit a slow depolarization even before the stimulus is applied,followed by a normal action potential.
B)The neuron will exhibit a slow hyperpolarization even before the stimulus is applied.
C)The neuron will show a normal resting potential,but will not exhibit depolarization when the stimulus is applied.
D)The neuron will exhibit rapid depolarization,but will not repolarize.
E)The neuron will depolarize normally,but then become hyperpolarized such that the membrane potential is much lower than usual.

Question 39

Indicate the mechanism responsible for the rapid depolarization that occurs as the "upsweep" of membrane potential peaks during the action potential.

A)closing of the voltage-gated Na⁺ channel activation gates
B)closing of the voltage-gated Na⁺ channel inactivation gates
C)opening of the voltage-gated K⁺ channel gates
D)both opening of the K⁺ channel gates and closing of the Na⁺ channel inactivation gates
E)both opening of the K⁺ channel gates and closing of the Na⁺ channel activation gates

Question 40

Saltatory conduction is a term applied to the "jumping" movement of action potentials

A)across electrical synapses.
B)along the postsynaptic membrane from dendrite to axon hillock.
C)in two directions at the same time.
D)from one neuron to another.
E)along myelinated axons.

Question 41

The class of neurotransmitters that most commonly acts as a modulator of postsynaptic cell response are the

A)biogenic amines.
B)amino acids.
C)acetylcholine.
D)neuropeptides.
E)gases such as nitric oxidE.

Question 42

Ionotropic receptors act by activating G proteins in target cells.

Question 43

Action potentials are typically also characterized as graded potentials.

Question 44

The exposed,unmyelinated gaps between glia on myelinated axons are also sites of voltage-gated Na⁺ channels.

Question 45

Gamma aminobutyric acid (GABA)is the most common inhibitory neurotransmitter in vertebrates.

Question 46

Most of the cells in your brain are neurons.

Question 47

The neurotransmitter released at neuromuscular junctions (where the neuron meets skeletal muscle)in vertebrates is

A)acetylcholine.
B)serotonin.
C)epinephrine.
D)GABA.
E)endorphin.

Question 48

The Nernst Equation is: E = 60 mV log₁₀ ([X_{extracellular}/X_{intracellular}]).Given this,the equilibrium potential for a given ion would be increased with an increase in its intracellular concentration.

Question 49

Disruption of neural signaling can produce profound changes in mood and behavior.Cocaine exerts its effects by

A)blocking norepinephrine and dopamine reuptake from synapses.
B)blocking serotonin reuptake from synapses.
C)preventing neurotransmitter vesicle fusion with presynaptic neuron membranes.
D)blocking the enzyme acetylcholinesterase.
E)binding to the GABA receptor to enhance inhibitory neurotransmission.

Question 50

Activities associated with the parasympathetic division of the autonomic nervous system include

A)resting and digesting.
B)release of both acetylcholine and epinephrine.
C)increased heart rate.
D)"fight-or-flight" response.
E)release of epinephrine only.

Question 51

The same neurotransmitter may produce either excitatory or inhibitory effects on postsynaptic neurons depending on the specific receptor type it binds.

Question 52

The central nervous system of vertebrate animals consists of

A)the brain.
B)the spinal cord.
C)all nerves in the body.
D)nerves originating at sensory receptors.
E)the brain and spinal cord.

Question 53

The portion of the brain that has shown the most dramatic changes in size in the evolution of birds and mammals is the

A)hindbrain.
B)midbrain.
C)forebrain.
D)cerebellum.
E)medulla oblongata.

Question 54

The main class(es)of neurotransmitters involved in regulating mood in vertebrate animals is/are

A)amino acids.
B)gases such as nitric oxide and carbon monoxide.
C)acetylcholine and amino acids.
D)acetylcholine.
E)the biogenic amines.

Question 55

Electrical synapses transmit signals through the use of "messengers" called neurotransmitters.

Question 56

The multi-purpose fluid that bathes the the central nervous system is called the

A)cerebrospinal fluid.
B)interstitial fluid.
C)lymph.
D)blooD.
E)arachnoid fluid.

Question 57

Damage to the cerebellum could result in

A)decreased ability to balance.
B)loss of hearing.
C)loss of vision.
D)loss of taste sensation.
E)diminished thermoreceptive sensation.

Question 58

The two distinct types of neurotransmitter receptors found in postsynaptic membranes are

A)metabotropic and neurotropic.
B)ionotropic and gonadotropic.
C)gonadotropic and neurotropiC.
D)neurotropic and isotopic.
E)metabotropic and ionotropic.

Question 59

Metabotropic receptors act by initiating changes in second messenger systems in target cells.

Question 60

The simplest nervous system found in nature is the nerve net.An example of an organism that senses and responds to its environment with this ancient system would be

A)a jellyfish.
B)an earthworm.
C)a frog.
D)a fiddler crab.
E)a cockroach.

Question 61

Overall brain size across mammals (e.g. ,an elephant vs.a bat)is a good predictor of behavioral complexity.

Question 62

The region of the human brain is that is critically important for monitoring and controlling movements is the

A)medulla oblongatA.
B)cerebellum.
C)hypothalamus.
D)basal nuclei.
E)cerebral cortex.

Question 63

The brain region responsible for producing hormones that are secreted by the pituitary gland is the

A)cerebrum.
B)cerebellum.
C)thalamus.
D)hypothalamus.
E)medulla oblongata.

Question 64

In mammals,the brain region that has become especially important as a "relay center" for information passing from sensory structures to the cerebrum is the

A)pons.
B)cerebellum.
C)hypothalamus.
D)thalamus.
E)hippocampus.

Question 65

The mammalian circadian pacemaker is located in the

A)hypothalamus.
B)brainstem.
C)somatosensory cortex.
D)adrenal glanD.
E)hippocampus.

Question 66

The level of the vertebrate nervous system responsible for the skeletal muscle responses to stimuli is the ___________________ system.

A)sensory
B)somatic
C)sympathetic
D)All of these answers are correct.

Question 67

New neuron synapses do not appear in the brain of adult vertebrate animals.

Question 68

Cranial nerves are connected directly to the brain.

Question 69

If the regulation of hunger and thirst mechanisms goes haywire,the brain region that is most likely damaged is the

A)cerebrum.
B)cerebellum.
C)thalamus.
D)hypothalamus.
E)medulla oblongata.

Question 70

You've just had a near miss in your car.Your pulse is racing and you notice your pupils are wide open when you look in your rearview mirror.What part of your autonomic nervous system is activated?

A)peripheral
B)sympathetic
C)parasympathetic
D)myelencephalon
E)neocortex

Question 71

Activities like playing a musical instrument regularly can affect the size of brain regions involved in performing these activities.

Question 72

Synaptic vesicles discharge their contents at the axon hillock region.

Question 73

A neurologist diagnoses a patient with damage to the hippocampus.This observation is consistent with the difficulties the patient reports with

A)forming memories of recent events.
B)effectively coordinating movements once initiated.
C)planning movements.
D)maintaining a steady and regular heartbeat.
E)perceiving tactile stimulation from different regions of their body.

Question 74

In a classic experiment,Otto Loewi electrically stimulated the vagus nerve of a frog heart.He then took the fluid bathing the stimulated heart and applied it to a second frog heart.The beating rate of both hearts slowed down with this treatment.Based on this response,you can assume the nerve he stimulated was part of the

A)parasympathetic system.
B)sympathetic system.
C)somatic system.
D)atrioventricular system.
E)central nervous system.

Question 75

The peripheral nervous system in a vertebrate can be divided into

A)the brain and spinal cord.
B)the sympathetic and parasympathetic systems.
C)the central nervous and sensory systems.
D)the somatic and autonomic systems.
E)muscles and glands.

Question 76

Which organisms have a CNS? Check all that apply.

Question 77

The sympathetic nervous system is part of the

A)central nervous system.
B)autonomic nervous system.
C)somatic nervous system.
D)learning and memory system.
E)limbic system in the brain mediating emotion.

Question 78

The somatic nervous system primarily regulates involuntary responses.

Question 79

The sympathetic and parasympathetic divisions of the autonomic nervous system tend to have opposing actions on target organs.

Question 80

The region of the human brain that is critically important for controlling heart rate and breathing is the

A)medulla oblongatA.
B)cerebellum.
C)thalamus.
D)hippocampus.
E)cerebral cortex.