PhysioEx Exercise 3

When the stimulus intensity increases, _______.

the number of action potentials increases

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

increasing the duration of the stimulus

At threshold, axons will _______.

Likely generate an action potential if refractory periods have elapsed.

Longer stimuli will allow for _______.

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 _______.

interspike interval

Increase in stimulus intensity _______.

increases the frequency of action potentials

The frequency of action potentials is _______.

the reciprocal of the interspike interval, and measured in hertz

During the relative refractory period, _______.

the stimulus must be above threshold to generate an action potential

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

The membrane depolarizes

Which of the following occurs during depolarization?

Sodium flows into the cell

Which of the following occurs during repolarization?

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?

leakage channels and voltage-gated potassium channels

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

Some sodium channels have been inactivated and cannot be reopened immediately

During the relative refractory period, _______.

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 until the interval reaches the absolute refractory period

When the stimulus voltage is increased, _______.

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

An action potential requires _______.

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

Which of the following blocks voltage-gated sodium channels?

tetrodotoxin and lidocaine

Which of the following is used to block pain?

lidocaine

Which of the following occurred in the presence of tetrodotoxin?

The number of action potentials decreased.

Which of the following occurred in the presence of tetrodotoxin?

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

The effects of lidocaine and tetrodotoxin were _______.

similar, but tetrodotoxin had a greater effect

A nerve is _______.

a bundle of axons

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

trigger zone

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

voltage

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

conduction or propagation

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

threshold voltage

Increasing the voltage resulted in which of the following?

no change to the action potential

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

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

The receptor potential is generated at the _______.

receiving region

Sensory transduction is defined as _______.

the conversion of a stimulus to a change in membrane potential

The receptor potential _______.

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 becomes less polarized.

Which of the following statements about receptor potentials is FALSE?

The receptor potential is carried by neuroglia

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

medullary region

The conducting region of the neuron is the _______.

axon

The typical concentration of sodium is _______.

lower than potassium intracellularly.

Which of the following describes a change from the resting membrane 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

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

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

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

sodium-potassium pump

Which of the following was able to detect pressure?

the Pacinian corpuscle and the free nerve ending

Which of the following does NOT describe graded potentials?

They are always depolarizing.

Which of the following responded to a chemical stimulus?

olfactory receptor

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

increased