Deck 7: The Nervous System and Neuronal Excitability

Question 1

When processing data to answer this multiple-choice question, you are utilizing the _______ of the nervous system.

A) motor function
B) integrative function
C) sensory function
D) autonomic function

Answer 1

B

Question 2

White matter in the brain gets it color from

A) the cell bodies of the neurons
B) the nodes of Ranvier
C) unmyelinated axons
D) myelinated axons

Answer 2

D

Question 3

There is a lower than normal level of CSF being formed. Using your knowledge of the functions of each of the types glial cells, you surmise that the _______ are malfunctioning.

A) oligodendrocytes
B) microglial cells
C) ependymal cells
D) Schwann cells

Answer 3

C

Question 4

Neuroglia play a variety of roles and are found throughout the nervous system. Which of the following neuroglia is found only in the peripheral nervous system?

A) Schwann cells
B) astrocytes
C) oligodendrocytes
D) ependymal cells

Question 5

A signal to cause your muscle to contract, pulling your hand away from a hot object, would travel along

A) autonomic neurons
B) sensory neurons
C) somatic neurons
D) autonomic and somatic neurons

Question 6

Retrograde and anterograde transport occur in the

A) axon
B) dendrites
C) cell body (soma)
D) axon hillock

Question 7

The kinesins in a cell have run out of ATP and are no longer moving. Predict what effect the failure of the kinesins will have on neuronal function.

A) Recycling of old materials will decrease.
B) ATP production will slow.
C) There will be a decrease in the amount of synaptic vesicles available for release.
D) The neuron will no longer receive input from other neurons.

Question 8

Action potentials will travel more slowly through myelinated axons than through non myelinated axons.

Question 9

______ are the cells of the nervous system which remove nervous tissue that is no longer functional.

A) Oligodendrocytes
B) Ependymal cells
C) Astrocytes
D) Microglial cells

Question 10

An investigator is trying to slow the rate of infection of neurons by the herpes simplex virus. Which of these proteins in the neuron could she target to prevent the virus from reaching the cell body where it could replicate?

A) dynein
B) kinesin
C) microtubules
D) dynein and microtubules

Question 11

A scientist discovers that a neuron does not have adequate stores of neurotransmitter. What part of the neuron is he observing?

A) the axon
B) the synaptic end bulbs
C) the dendrites
D) the cell body

Question 12

Each part of a neuron carries out a specific function, just as different types of neurons are responsible for specific actions. In the following choices, which paring of neuron structure is paired with a type of neuron that carries out a similar function?

A) cell body (soma) and efferent neurons
B) dendrites and afferent neurons
C) axons and interneurons
D) dendrites and efferent neurons

Question 13

Astrocytes are the most common glial cell.

Question 14

Information is sent from the dendrites to the ________, where an action potential may be generated.

A) cell body (soma)
B) axon terminal
C) synaptic end bulb
D) axon hillock

Question 15

Select the division of the nervous system that allows you to know that coffee is brewing in another room.

A) sensory
B) sympathetic
C) parasympathetic
D) somatic

Question 16

The somatic, sympathetic, parasympathetic and enteric divisions of the nervous system all play a role in the __________ of the nervous system.

A) sensory function
B) integrative function
C) motor function
D) sensory and motor functions

Question 17

A major function of the nervous system is communication that allows our bodies to maintain homeostasis. In many cases reflexes will occur without our awareness. Which function of the nervous system is bypassed in this case?

A) sensory function
B) motor function
C) integrative function
D) none; all functions occur in reflexes

Question 18

An individual touches a sharp object and cries out in pain, but is unable to pull her hand away from the object. In this situation, the _________ neurons are the most likely reason she cannot respond.

A) sensory neurons
B) sympathetic neurons
C) parasympathetic neurons
D) somatic neurons

Question 19

A surgeon is repairing damage to an individual's abdominal area, and accidentally connects a nerve that originally controlled the smooth muscle of the GI tract to the skeletal muscle of the abdominal wall. Hypothesize what might happen in this instance.

A) The individual will no longer have voluntary control of the smooth muscle in his GI tract.
B) The nerve will change divisions and contain only somatic neurons.
C) Nothing, because the tissue of the GI tract responds only to the enteric nervous system, and the autonomic innervation was not vital.
D) This area of the GI tract will no longer be able to exchange information with the CNS through this nerve.

Question 20

Which of the following statements is true concerning a difference between neurons and neuroglia?

A) Unlike neuroglia, neurons are found in the central nervous system.
B) Unlike neuroglia, neurons have an axon.
C) In contrast to neuroglia, neurons are smaller and therefore more of them are found in the nervous system.
D) In contrast to neuroglia, neurons can multiply in the mature nervous system.

Question 21

Movement of ions through channels occurs as a result of gradients. If left alone, these gradients would eventually run down (ie reach equilibrium). How do active transporters (pumps) like the Na⁺/K⁺ ATPase maintain the gradients?

A) They pump charges only across the membrane, maintaining the electrical gradient.
B) They pump neutral elements (atoms) only across the membrane, maintaining the concentration gradient.
C) They pump ions across the membrane maintaining both electrical and concentration gradients.
D) They pump water across the membrane maintaining osmotic and concentration gradients.

Question 22

Which of the following choices would result in the greatest flow of ions across the membrane?

A) a large V_m
B) a large number of closed ion channels
C) a large membrane resistance
D) a small difference in ion concentrations across the membrane

Question 23

If the myelin serves to insulate an axon, decreasing the loss of electrical signal and increasing speed of conduction, then which of the following statements accurately predicts where myelin will have the largest effect?

A) Neurons with short axons that relay information of minor importance.
B) Neurons with short axons that relay critical information.
C) Neurons with long axons that relay information of minor importance.
D) Neurons with long axons that relay critical information.

Question 24

Which of the statements below correctly explains the difference between the information calculated by the Nernst and the Goldman-Hodgkin-Katz (GHK) equations?

A) The Nernst calculates the resting membrane potential for a membrane, but GHK does not.
B) The Nernst calculates the equilibrium potential for anions, and the GHK for cations.
C) The Nernst calculates the equilibrium potential for a single ion and the GHK for the resting membrane potential.
D) The Nernst calculates the equilibrium potential for an ion with a single charge and the GHK for an ion with a charge of two or more.

Question 25

Anionic proteins and phosphates have little influence over the resting membrane potential (RMP) because

A) they are found in roughly equal concentrations across the membrane
B) they are negatively charged, and the rmp relies on positive charges
C) they are bound to cations and thus can't cross the membrane
D) they do not have leak channels and thus can't cross the membrane

Question 26

Key characteristics that define an excitable cell are

A) responding to a stimulus
B) generating an electrical signal
C) producing neurotransmitters
D) generating an action potential as a response to a stimulus

Question 27

A ______ most directly results in the contraction of a muscle cell.

A) membrane potential
B) muscle action potential
C) nerve action potential
D) graded potential

Question 28

Regrowth of neurons in injured areas of the central nervous system does not generally occur because

A) astrocytes multiply rapidly, blocking potential regrowth of a neuron
B) there are plenty of other neurons to take the damaged neuron's place
C) inhibitory proteins produced by microglia stop and repair
D) Schwann cells fail to produce a regeneration tube

Question 29

A cell with leak channels that are only permeable to Cl^- has been placed in a petri dish. Which of the following statements accurately describes the relationship between the concentration gradient and the Cl^- equilibrium potential (E_Cl)?

A) A higher concentration of Cl^- outside the cell will create a positive equilibrium potential.
B) A higher concentration of Cl^- inside the cell will create a positive equilibrium potential.
C) A higher concentration of Cl^- inside the cell will create a negative equilibrium potential.
D) It does not matter what the initial concentration is because Cl^- will always reach a negative equilibrium potential.

Question 30

A cell at rest will be more likely to lose K⁺ than gain Na⁺ because the membrane has

A) more K⁺ leak channels compared to Na⁺ channels
B) more K⁺ voltage-gated channels compared to Na⁺ channels
C) more K⁺ ligand-gated channels compared to Na⁺ channels
D) more K⁺ mechanically-channels compared to Na⁺ channels

Question 31

Leak channels only allow ions to move out of the cell (which is why they are called "leak" channels.

Question 32

The equilibrium potential measures the point at which the force of the electrical gradient exactly opposes the force of the _______ gradient on a particular ion, thus preventing any net movement across the membrane.

A) concentration gradient
B) pressure gradient
C) osmotic gradient
D) thermal gradient

Question 33

The membrane potential (V_m), a measure of the charge difference across the membrane depends upon the

A) number of ions on each side of the membrane
B) number of open ion channel
C) charges of ions on each side of the membrane
D) All choices will affect the membrane's ability to separate charges.

Question 34

The resting membrane potential is a measure of charge difference across the unstimulated cell membrane. This charge difference can exist because

A) the membrane is permeable to all substances
B) the membrane has channels that serve as conductors
C) the membrane has lipid components that serve as an insulator
D) the membrane is permeable to all substances because of its channels

Question 35

Ions cross the membrane through channels. What factors will affect the movement of the ions?

A) concentration gradients
B) electrical gradients
C) pressure gradients
D) chemical and electrical gradients

Question 36

Regeneration is more likely to occur in the peripheral nervous system because the oligodendrocytes form a regeneration tube.

Question 37

Which statement is true about the comparison of plasticity and regeneration in neurons?

A) plasticity only occurs in the CNS while regeneration only occurs in the PNS
B) new neurons are formed in plasticity, but not regeneration
C) plasticity and regeneration are both equally likely to occur
D) plasticity involves changes in synaptic strength or number while regeneration involves repair

Question 38

You are working with some new neural cells and accidentally spill a few drops of a chemical solution into the petri dish. Shortly afterwards, you notice an increase in graded potentials in the cells. You hypothesize that the channels responsible for these graded potentials are

A) ligand-gated
B) leak channels
C) mechanically-gated
D) voltage-gated

Question 39

While some channels can have open states regulated by stimuli, others are random. What common term among those that are opened by a stimulus?

A) leak
B) gated
C) channel
D) ion

Question 40

You have discovered a novel cell that has leak channels for ions. Predict which ion will have the largest influence over the resting membrane potential.
a) Na⁺, relative permeability = 0.09
b) Ca ²⁺, relative permeability = 0.05
c) Mg ²⁺, relative permeability = 0.5
d) Cl^-, relative permeability = 0.3

Question 41

How can one tell if action potentials are generated by a threshold or suprathreshold stimuli?

A) the suprathreshold will have the largest amplitude
B) threshold stimuli will not always produce an action potential
C) the suprathreshold stimulus will create a higher frequency of action potentials
D) there in no difference in action potentials generated by either type of stimulus

Question 42

Changes in ion concentrations in the extracellular fluid can alter electrochemical gradients making cells more or less likely to depolarize.

Question 43

A postsynaptic cell in a synapse could be a/an

A) neuron
B) skeletal muscle cell
C) endocrine cell
D) All of these choices could be a postsynaptic cell.

Question 44

You have observed that graded potentials typically occur in the dendrites and cell body. What is the underlying reason for this?

A) Graded potentials can only travel a short distance by local current flow.
B) Graded potentials are caused by ligand and mechanically-gated channels that are most frequently found in dendrites and cell bodies.
C) Graded potentials are caused only by Na⁺ and K⁺ flowing through channels.
D) Graded potentials are both depolarizing and hyperpolarizing, which means they can't occur in axons where only depolarizing signals occur.

Question 45

How does increasing the extracellular calcium concentration lead to a decrease in excitability?

A) Ca²⁺ can block Na⁺ channels, so the extra concentration means fewer channels are available for Na⁺ to move through.
B) Ca²⁺ increases the voltage threshold required to open the Na⁺ channels, so the extra concentration means channels require more stimulus.
C) Ca²⁺ decreases the voltage threshold required to open the K⁺ channels, so the extra concentration means K⁺ channels will open sooner, hyperpolarizing the cell.
D) It makes the outside of the cell more positive, so by comparison the inside is more negative and therefore less likely to depolarize.

Question 46

A fellow student is studying graded potentials and decides that any time K⁺ is involved, the potential must be hyperpolarizing. Which of the following arguments could accurately explain that the ion alone doesn't determine this?

A) Ions move based on an electrochemical gradient. If the concentration of K⁺ outside the cell is greatly increased, then it would move in, depolarizing the cell.
B) When an ion crosses the membrane, it brings its charge with it. Because K⁺ is positively charged, it can only depolarize a cell (make it less negative.)
C) K⁺ basically doesn't move across the membrane unless it is actively transported, and potentials involve the movement of ions through channels.
D) Many types of ions (with their charges) are located inside and outside the cell. It is the concentrations of those other ions that determines whether a channel opening will lead to a depolarizing or hyperpolarizing potential.

Question 47

Speed of conduction of action potentials along an axon is increased in

A) axons with a larger diameter
B) axons that are myelinated
C) axons with more axon collaterals
D) axons with both myelin and a larger diameter

Question 48

Saltatory conduction is different from continuous conduction because it

A) occurs in axons with myelin on them
B) occurs in dendrites
C) is slower than continuous conduction
D) utilizes more energy than continuous conduction

Question 49

You have accidentally poisoned the Na⁺/K⁺ ATPase pump with ouabain. Predict what effect this might have on the action potential.

A) None, as action potentials rely on channels for Na⁺ and K⁺ to cross the membrane, not pumps.
B) It will make action potentials more likely to occur as the pump normally makes the cell more negative, so without it the membrane will reach threshold more easily.
C) It will not have an immediate effect, but eventually action potentials will stop as the Na⁺ and K⁺ gradients are depleted.
D) It will shorten the duration of the action potential as there will not be as many ions available to cross the membrane.

Question 50

Place the following events of the action potential in the correct order. 1) Voltage-gated Na+ channels open, and Na+ flows in
2) Voltage-gated K+ channels close, membrane potential returns to rest
3) Membrane is depolarized to threshold
4) Voltage-gated Na⁺ channels close
5) Voltage-gated K⁺ channels open, membrane rapidly repolarizes
6) Membrane rapidly depolarizes

A) 1, 3, 6, 5, 4, 2
B) 3, 1, 6, 4, 5, 2
C) 5, 2, 1, 6, 4, 3
D) 6, 1, 3, 4, 5, 2

Question 51

In myelinated axons, the channels found in the nodes of Ranvier are

A) similar to the channels found on the dendrites
B) similar to the channels found on sensory receptors
C) similar to the channels found in the axon hillock
D) unique and unlike channels found anywhere else in the neuron

Question 52

The voltage-gated Na⁺ channels have inactivation gates which cause the action potential to have specific characteristics such as

A) maximal frequency due to the absolute refractory period
B) travel one-direction (not go back where it came from)
C) inability to sum action potentials
D) All these characteristics are due to the inactivation gates.

Question 53

What would happen to an action potential if the voltage-gated Na⁺ channels closed earlier than normal?

A) The amplitude would be smaller, but the duration would be similar.
B) The amplitude would be similar, but the duration would be shorter.
C) The amplitude and duration would be similar, but fewer K⁺ channels would open.
D) The action potential would remain unchanged.

Question 54

Which of the following is NOT a type of graded potential?

A) post-synaptic potential
B) receptor potential
C) end plate potential
D) resting membrane potential

Question 55

A graded potential is generated half-way along a dendrite's length. The graded potential

A) will travel toward the cell body
B) will travel away from the cell body
C) will stay near the site where it was generated, as graded potentials can't travel far
D) will travel both toward and away from the cell body

Question 56

Energy is required to do work. What type of work is being done by the Na⁺/K⁺ ATPase that allows it to maintain a steady state in the neuron?

A) chemical work
B) mechanical work
C) transport work
D) both chemical and transport work

Question 57

Which of the following conditions would create this graph when a channel opens and the specific ion passes through?

A) Cl^- concentration higher outside a cell
B) Cl^- concentration higher inside a cell
C) Na⁺ concentration higher inside a cell
D) either Cl^- or Na⁺ concentrations higher inside a cell

Question 58

A scientist wants to study the effects of summation on graded potentials. Her assistant applies the stimuli, but there is no apparent result. Compose a situation that would explain these results.

A) The stimuli were given, but they did not reach threshold.
B) The stimuli were given too soon after a trial run and the membrane was still in a refractory period.
C) The stimuli caused a hyperpolarization, but graded potentials are only depolarizing.
D) Two stimuli, equal in amplitude, but opposite in polarity were given and when summed they cancelled each other out.

Question 59

Graded potentials exhibit a number of characteristics including

A) having depolarizing or hyperpolarizing potentials
B) typically being found in cell bodies or dendrites
C) being generated by ligand or mechanically-gated ion channels
D) All of the choices are characteristics of graded potentials.

Question 60

Action and graded potentials both use local current flow, but action potentials can travel long distances while graded potentials decay. How is this possible?

A) Graded potentials only use Na⁺ and K⁺, while action potentials use other ions.
B) Action potentials are regenerated as they travel along the axon.
C) Refractory periods allow the channels to rest between action potentials so that they can travel a longer distance.
D) Myelin prevents all charges from leaking out of the axon.

Question 61

Summation of postsynaptic potentials determines whether or not an action potential will be generated at the axon hillock. The final amplitude of the summed potentials is dependent upon

A) distance the post-synaptic potential has traveled
B) the polarity of the potential (epsp or ipsp)
C) the timing of the potential (did they arrive close enough together to be summed)
D) All of the choices will affect the final amplitude.

Question 62

Depolarizing post-synaptic potentials are can also be called excitatory postsynaptic potentials (EPSPs) because they

A) increase the chances that the membrane will reach threshold
B) increase the chances that the membrane will return to its resting state
C) generate an action potential every time
D) cause dramatic changes in the postsynaptic neuron

Question 63

Metabotropic receptors can open or close ion channels indirectly. The intermediary is typically a

A) ligand-gated ion channel
B) G-protein
C) K⁺ ion
D) secondary neurotransmitter

Question 64

Based on the figure, if Neuron B releases a neurotransmitter that causes a hyperpolarizing potential in Neuron A, would Neuron C be affected, and if so, how?

A) Yes, the effect on A would lead to a decrease in neurotransmitter release, thus decreasing the output to C.
B) Yes, the effect on A would lead to a increase in neurotransmitter release, thus increasing the output to C.
C) No, because A doesn't directly interact with C.
D) No, because hyperpolarizing potentials don't affect neurotransmitter release.

Question 65

A patient is having problems with tissues that use the acetylcholine (ACh) receptor. You suspect the problem is with the nicotinic ACh receptors because the problems are occurring with

A) cardiac muscle
B) smooth muscle
C) skeletal muscle
D) glands

Question 66

Identify the true statement about presynaptic modulation.

A) Presynaptic modulation affects the amount of neurotransmitter released onto the target.
B) Presynaptic modulation is a direct relationship between two neurons.
C) Presynaptic modulation always reflects facilitation of the synapse.
D) Presynaptic modulation always reflects inhibition of the synapse.

Question 67

Electrical synapses send ions and other small particles directly between cells via gap junctions. This allows

A) communication to occur in both directions
B) faster speed of communication
C) groups of cells to be linked together so that they seem to act as a unit
D) All of these options are possible because of gap junctions.

Question 68

Assume the potentials from the following combinations of dendrites reach the axon hillock/trigger zone at the same time. Which combination will have the greatest chance of generating an action potential?

A) 1, 2, 4
B) 2, 3, 4
C) 3, 4, 5
D) 1, 4, 5

Question 69

What are the two size classifications of neurotransmitters?

A) excitatory and inhibitory
B) small-molecule neurotransmitters and neuropeptides
C) solids and gases
D) hydrophilic and hydrophobic

Question 70

A neuron generated postsynaptic potentials from several neurons, all of which are below threshold from the start. What must occur for an action potential to be generated?

A) The potentials must be equally divided between EPSPs and IPSPs.
B) The summation of the potentials must be at or above threshold.
C) The potentials must all arrive at different times.
D) The potentials must all travel great distances.

Question 71

In a dendroaxonic synapse the part of the postsynaptic cell receiving the signal is the

A) dendrite
B) cell body
C) axon
D) myelin

Question 72

An action potential has reached the synaptic end bulb, but there is no neurotransmitter release. This could be caused by

A) failure of the voltage-gated k⁺ channels to open, thus preventing repolarization
B) failure of the synaptotagmin to form channels for the neurotransmitter to cross the membrane
C) failure of voltage-gated ca²⁺ channels to open, preventing ca²⁺ from entering the cell
D) failure of kinesins to transport vesicles across the synaptic cleft

Question 73

Ionotropic receptors would be beneficial when

A) suddenly swerving to avoid hitting an object
B) maintaining hormone balances
C) modifiying intracellular proteins
D) removing Cl^- from a cell

Question 74

Electrical synapses are different from chemical synapses because

A) they can only send signals in one direction
B) they are able to synchronize a group of cells
C) they are a slower way to send signals between cells
D) they provide a direct cytoplasmic connection between the two cells

Question 75

You have been given an unknown neurotransmitter to identify. What characteristics would indicate that it is more likely a small-molecule neurotransmitter?

A) it causes ion channels to open or close
B) it alters the strength of the post-synaptic cell response
C) it affects the synthesis of neurotransmitter in the presynaptic cell
D) it has long lasting effects

Question 76

The benefit of presynaptic facilitation is that it

A) maintains the level of neurotransmitter release regardless of the amount of stimulus, thus strengthening the synapse
B) ensures that all axon collaterals stimulate their postsynaptic targets equally
C) allows the nervous tissue to selectively modulate input at synapses
D) allows the postsynaptic neuron to increase the number of receptors for the neurotransmitter

Question 77

While observing a synaptic end bulb, the investigator sees a decrease in the amount of neurotransmitter in the end bulb when the cell is stimulated, but then shortly thereafter, discovers that the amount of neurotransmitter in the cell seems to be increasing. One could hypothesize that the neurotransmitter is removed from this synapse by

A) diffusion
B) enzymatic degradation
C) reuptake by the neuron
D) uptake by glial cells

Question 78

In the synaptic end bulb, the action potential leads to the release of neurotransmitter. What links these two types of signals?

A) The action potential triggers voltage-gated Na⁺ channels to open and the depolarization causes the vesicle walls to merge with the membrane.
B) The action potential causes a change in the proteins on the vesicle membranes such that the vesicle binds to the cell membrane and begins exocytosis.
C) The action potential triggers voltage-gated Ca²⁺ channels to open and the Ca²⁺ that flows in starts a cascade of protein reactions that allows exocytosis of the neurotransmitters.
D) The action potential causes K⁺ to leave during repolarization and the decrease in K⁺ concentration triggers vesicles to bind to the membrane, releasing their contents.

Question 79

At the postsynaptic membrane in a chemical synapse, the membrane converts a ______ signal to a ______ signal.

A) chemical; electrical
B) mechanical; chemical
C) electrical; chemical
D) mechanical; electrical

Question 80

Ionotropic receptors are typically associated with fast postsynaptic responses because the receptors

A) have rapid responses
B) have short-term responses
C) make use of second messenger systems
D) have both rapid and short-term responses