PhysioEx 3- Neurophysiology

Which of the following statements about receptor potentials is FALSE?

-Odor molecules can act as stimuli.
-The receptor potential is carried by neuroglia.
-The receptor proteins respond to stimuli.
-They can trigger an action potential.

The receptor potential is carried by neuroglia.

Which of the following is NOT a functional region of a neuron?

secretory region
conducting region
receiving region
medullary region

medullary region

The conducting region of the neuron is the _______.

cell body
axon
axon terminal
dendrite

axon

The typical concentration of sodium is _______.

– the same as potassium intracellularly.
– lower than potassium extracellularly.
– lower than potassium intracellularly.
– higher than potassium intracellularly.

– lower than potassium intracellularly.

Which of the following describes a change from the resting membrane potential?

– an action potential
– a synaptic potential
– a receptor potential
– a receptor potential, a synaptic potential or an action potential

a receptor potential, a synaptic potential or an action potential

What effect did increasing the extracellular potassium have on the resting membrane potential?

– The resting membrane potential became less negative.
– The resting membrane potential became more negative.
– The resting membrane potential did not change.
– The resting membrane potential disappeared.

The resting membrane potential became less negative.

What effect did decreasing the extracellular sodium have on the resting membrane potential?

– Only a small change occurred, because the sodium channels were mostly open.
– The resting membrane potential disappeared.
– Only a small change occurred, because the resting neuron is not very permeable to sodium.
– The resting membrane potential became less negative.

Only a small change occurred, because the resting neuron is not very permeable to sodium.

The channels that provide for the movement of potassium in the resting neuron are _______.

– leakage and chemically gated.
– chemically gated
– voltage gated
– leakage

leakage

Establishing the resting membrane potential requires energy through the use of the _______.

– sodium-glucose pump
– potassium-glucose pump
– sodium-potassium pump
– sodium leakage channels

sodium-potassium pump

The receptor potential is generated at the _______.

receiving region
conducting region
output region
secretory region

receiving region

Sensory transduction is defined as _______.

– the conversion of a stimulus to a change in membrane potential
– the disappearance of the perception of a stimulus
– the conversion of a light stimulus into pain
– a change in the amplitude of a receptor potential

– the conversion of a stimulus to a change in membrane potential

The receptor potential _______.

– can be graded with stimulus intensity
– amplitude can vary with the stimulus intensity, requires the appropriate stimulus and can be graded with a stimulus intensity
– amplitude can vary with the stimulus intensity
– requires the appropriate stimulus

amplitude can vary with the stimulus intensity, requires the appropriate stimulus and can be graded with a stimulus intensity

Which of the following describes a depolarization?

– The membrane potential becomes more polarized.
– The membrane potential becomes more negative.
– The membrane becomes less polarized.
– The membrane, which was formerly not polarized, now is polarized.

The membrane becomes less polarized.

Which of the following was able to detect pressure?

– the Pacinian corpuscle and the free nerve ending
– free nerve ending
– olfactory receptor
– Pacinian corpuscle

the Pacinian corpuscle and the free nerve ending

Which of the following does NOT describe graded potentials?

– They vary with the intensity of the stimulus.
– They are changes to the membrane potential.
– They are always depolarizing.
– They are local changes.

They are always depolarizing.

Which of the following responded to a chemical stimulus?

– Pacinian corpuscle
– free nerve ending
– olfactory receptor
– both the Pacinian corpuscle and the olfactory receptor

olfactory receptor

When the intensity of the appropriate stimulus was increased, the amplitude of the response _______.

was zero
did not change
decreased
increased

increased

A nerve is _______.

another term for a neuron
a cluster of cell bodies
a bundle of axons
another term for nerve fiber

a bundle of axons

The region on the neuron where action potentials are generated is called the ______.

trigger zone
depolarization zone
stimulator zone
dendrite

trigger zone

In this simulation, ___________________ will be used to stimulate the axon.

light
heat
voltage
chemicals

voltage

We describe the regeneration of the action potential down the membrane of the axon of the neuron as _______.

hyperpolarization
conduction or propagation
conduction
propagation

conduction or propagation

The minimum voltage that is required to generate an action potential is called the _______.

depolarization voltage
propagation voltage
threshold voltage
trigger voltage

threshold voltage

Increasing the voltage resulted in which of the following?

– an increase in the rate of propagation of the action potential
– an increase in the size of the action potential
– a decrease in the rate of propagation of the action potential
– no change to the action potential

no change to the action potential

An axon that is more negative than the resting membrane potential is said to be _______.

depolarized
hyperpolarized
at threshold
graded

hyperpolarized

If an increase in extracellular potassium hyperpolarizes a neuron, which of the following would be correct?

-It would change the membrane potential to a more negative value.
-It would decrease the flow of sodium out of the cell.
-It would change the membrane potential to a less negative value.
-It would increase the flow of sodium out of the cell.

-It would change the membrane potential to a more negative value.

An action potential requires _______.

– voltage-gated sodium channels to open
– sodium to flow with its electrochemical gradient
– chemically gated sodium channels to open
– voltage-gated sodium channels to open and sodium to flow with its electrochemical gradient

voltage-gated sodium channels to open and sodium to flow with its electrochemical gradient

To reach threshold, the amount of sodium _______.

– entering the cell must overcome the potassium exiting
– exiting the cell must overcome the potassium exiting
– entering the cell must overcome the potassium entering
– exiting the cell must overcome the potassium entering

entering the cell must overcome the potassium exiting

Which of the following blocks voltage-gated sodium channels?

lidocaine
tetrodotoxin
tetrodotoxin and lidocaine
potassium

tetrodotoxin and lidocaine

Which of the following is used to block pain?

tetrodotoxin
tetrodotoxin and lidocaine
lidocaine
potassium

lidocaine

Which of the following occurred in the presence of tetrodotoxin?

The size of the action potential decreased.
The number of action potentials increased.
The number of action potentials decreased.
The size of the action potential increased.

The number of action potentials decreased.

Which of the following occurred in the presence of tetrodotoxin?

An action potential was always seen at R1.
All action potentials were missing.
An action potential was always seen at R1 and R2.
An action potential was always seen at R2.

An action potential was always seen at R1.

In the presence of lidocaine, the action potential was NOT affected at R1 because _______.

– lidocaine was applied downstream of R1
– there are no voltage-gated sodium channels to be affected
– lidocaine doesn’t have an effect on the generation of action potentials
– lidocaine was applied upstream of R1

lidocaine was applied downstream of R1

The effects of lidocaine and tetrodotoxin were _______.

– identical
– similar, but lidocaine had a greater effect
– similar, but tetrodotoxin had a greater effect
– very different, because lidocaine had no effect

similar, but tetrodotoxin had a greater effect

Which of the following occurs first in the generation of an action potential?

Voltage-gated sodium channels open.
Voltage-gated potassium channels open.
The membrane depolarizes.
The membrane repolarizes.

The membrane depolarizes.

Which of the following occurs during depolarization?

Both A and C occur.
Voltage-gated sodium channels close.
Voltage-gated potassium channels close.
Sodium flows into the cell.
All of the above occur.

Sodium flows into the cell.

Which of the following occurs during repolarization?

– Voltage-gated sodium channels open. Sodium flows into the cell.
– Voltage-gated potassium channels remain open and some voltage-gated sodium channels inactivate. Potassium flows into the cell.
– Voltage-gated sodium channels open and some voltage-gated potassium channels inactivate. Sodium flows out of the cell.
– Voltage-gated potassium channels open and some voltage-gated sodium channels inactivate. Potassium flows out of the cell.
– Voltage-gated potassium channels open and potassium flows into the cell.

Voltage-gated potassium channels open and some voltage-gated sodium channels inactivate. Potassium flows out of the cell.

Which of the following allow the movement of potassium through the neuronal membrane?

simple diffusion
leakage channels
leakage channels and voltage-gated potassium channels
voltage-gated potassium channels

leakage channels and voltage-gated potassium channels

Why does the threshold increase when the interval between the stimuli decreases?

– Potassium is flowing into the cell.
– Calcium is flowing out the cell.
– Sodium is flowing out of the cell.
– Some sodium channels have been inactivated and cannot be reopened immediately.

Some sodium channels have been inactivated and cannot be reopened immediately

During the relative refractory period, _______.

– a second action potential cannot be generated, no matter how strong the stimulus.
– the flow of potassium is also depolarizing the neuron.
– another action potential can be generated provided the stimulus is large enough.
– another action potential can be generated provided the stimulus is relatively smaller than the original stimulus.

another action potential can be generated provided the stimulus is large enough

When the interval between the stimuli decreases, _______.

– a second action potential is generated as long as the stimulus is above threshold
– a second action potential is generated until the interval reaches the relative refractory period
– a second action potential is generated until the interval reaches the absolute refractory period
– a second action potential is generated regardless of the stimulus and the interval

a second action potential is generated until the interval reaches the absolute refractory period

When the stimulus voltage is increased, _______.

– sodium permeability into the cell increases to overcome the potassium exiting
– a greater-than-threshold depolarization results and sodium permeability into the cell increases to overcome the potassium exiting.
– a greater-than-threshold depolarization results
– sodium permeability into the cell decreases

a greater-than-threshold depolarization results and sodium permeability into the cell increases to overcome the potassium exiting

When the stimulus intensity increases, _______.

– the number of action potentials decreases
– the size of the action potential decreases
– the size of the action potential increases
– the number of action potentials increases

the number of action potentials increases

In this activity, which of the following will increase the stimulus intensity?

– increasing the absolute refractory period
– decreasing the absolute refractory period
– increasing the duration of the stimulus
– increasing the relative refractory period

increasing the duration of the stimulus

At threshold, axons will _______.

– Usually be at the end of their absolute refractory period.
– Begin to hyperpolarize the membrane potential.
– Likely generate an action potential if refractory periods have elapsed.
– Always generate an action potential.

Likely generate an action potential if refractory periods have elapsed.

Longer stimuli will allow for _______.

-the absolute refractory period to finish
– more action potentials to occur, the absolute refractory period to finish and the relative refractory period to finish
– the relative refractory period to finish
– more action potentials to occur

more action potentials to occur, the absolute refractory period to finish and the relative refractory period to finish

The time interval between action potentials is called the _______.

potential frequency
threshold interval
interspike interval
threshold frequency

interspike interval

Increase in stimulus intensity _______.

– increases the duration of the action potential
– increases the frequency of action potentials
– has no effect on action potentials
– increases the size of the action potential

increases the frequency of action potentials

The frequency of action potentials is _______.

– measured in hertz, and the same as the relative refractory period
– the reciprocal of the interspike interval, and measured in hertz
– the same as the relative refractory period
– the reciprocal of the interspike interval
– measured in hertz

– the reciprocal of the interspike interval, and measured in hertz

During the relative refractory period, _______.

– adaptation occurs
– the stimulus must be above threshold to generate an action potential
– the stimulus must be below threshold to generate an action potential
– no action potentials are generated

the stimulus must be above threshold to generate an action potential

Which of the following is described correctly?

– Schwann cells provide the myelination in the peripheral nervous system.
– Astrocytes provide the myelination in the central nervous system.
– Oligodendrocytes provide the myelination in the peripheral nervous system.
– Schwann cells provide the myelination in the central nervous system.

Schwann cells provide the myelination in the peripheral nervous system.

The rate with which an action potential travels along an axon _______.

– is measured in meters/sec
– is called the conduction velocity
– is called the conduction velocity and is measured in volts/sec
– is measured in volts/sec
– is called the conduction velocity and is measured in meters/sec

is called the conduction velocity and is measured in meters/sec

Which of the following describes a B fiber?

– small diameter, unmyelinated
– large diameter, lightly myelinated
– medium diameter, lightly myelinated
– small diameter, lightly myelinated

medium diameter, lightly myelinated

The nodes of Ranvier are _______.

– locations on the axon where the myelin sheath is very heavy
– trigger zones of an axon
– a type of glial cell
– locations on the axon where the myelin sheath is absent

locations on the axon where the myelin sheath is absent

Which fibers generate the smallest value for conduction velocity?

A fibers
B fibers
D fibers
C fibers

C fibers

The time interval for conduction would be shortest with

– the largest unmyelinated axons
– the smallest and most heavily myelinated axons
– the largest and most heavily myelinated axons
– the smallest unmyelinated axons

the largest and most heavily myelinated axons

Increasing the amount of myelination _______.

– increases the time between action potentials
– increases the time between action potentials only for small-diameter axons
– decreases the time between action potentials
– has no effect on the time between action potentials

decreases the time between action potentials

In this activity, the stimulus voltage used was _______.

– altered to accommodate the structural differences
– the same for all of the axons
– suprathreshold for all of the axons
– the same for all of the axons and suprathreshold for all of the axons

the same for all of the axons and suprathreshold for all of the axons