Physiological Psych. Module 1.2 Quiz

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Which event will increase the concentration gradient of sodium?​

increasing activity of the sodium-potassium pump

Which action would depolarize a neuron?​

increasing membrane permeability to sodium

When a neuron's membrane is at rest, the concentration gradient tends to move sodium ____ the cell and the electrical gradient tends to move it ____ the cell.​

into; into

Electrical gradients lead to the ____.​

movement of ions to areas having opposite electrical charges

The resting potential is mainly the result of ____.​

negatively charged proteins inside the cell

The resting potential of a neuron refers to the ____.​

net negative charge on the inside of the neuron

According to the all-or-none law, ____.​

once an axon reaches threshold, the amplitude and velocity of an action potential are nearly equal each time

Which of the following describes selective permeability?​

only certain molecules are allowed to cross the membrane freely

When the potential across a membrane reaches threshold, the sodium channels ____.​

open to let sodium enter the cell rapidly

When a neuron's membrane is at rest, the concentration gradient tends to move potassium ____ the cell and the electrical gradient tends to move it ____ the cell.​

out of; into

Voltage-activated channels are channels for which a change in the voltage across the membrane alters their ____.​

permeability

When the neuronal membrane is at rest, the potassium leak channels ____.​

permit potassium ions to pass slowly

Local anesthetic drugs attach to the sodium channels of the membrane, which ____.​

prevents sodium ions from entering and stopping action potential

At the peak of the action potential, the electrical gradient of potassium ____.​

pushes potassium out of the cell

The primary feature of a neuron that prevents the action potential from traveling back from where it just passed is the ____.​

refractory period

What term describes the difference in voltage that typically exists between the inside and the outside of a neuron?​

resting potential

What occurs when depolarization is less than the cell's threshold?​

sodium crosses the membrane only slightly more than usual

The action potential of a neuron depends mostly on what movement of ions?​

sodium ions entering the cell

In the normal course of an action potential, ____.​

sodium remains much more concentrated outside than inside the neuron

Which of the following is an advantage of having a resting potential?​

the cell is prepared to respond quickly to a stimulus

The idea that a neuron's membrane is polarized refers to a difference in electrical potential between ____.​

the inside and the outside of the membrane

Which of the following describes the transmission of information in a local neuron?​

the signal decreases in strength as it travels

After the peak of an action potential, what prevents sodium ions from continuing to enter the cell?​

the sodium gates in the membrane close

What is one major cause for the resting potential of a neuron's membrane?​

the sodium-potassium pump

The neuron will produce an action potential only if the depolarization exceeds the ____.​

threshold of excitation

What is the approximate resting potential of the inside of a neuron's membrane, relative to the outside?​

-70 millivolts

What causes potassium ions to leave the axon just after the peak of the action potential?​

a continuing concentration gradient and the opening of the potassium gates

The all-or-none law states that ____.​

a neuron produces an action potential of maximal strength, or none at all

When the neuronal membrane is at rest, the sodium channels ____.​

are closed, so there is almost no flow of sodium

At what point do the sodium gates begin to close, shutting out further entry of sodium into the cell?​

at the peak of the action potential

Ordinarily, stimulation of a neuron takes place ____.​

at the synapse

A drug that blocks the sodium gates of a neuron's membrane will ____.​

block the action potential

When a membrane is at rest, what attracts sodium ions to the inside of the cell?​

both an electrical gradient and a concentration gradient

When a neuron is at rest, what is primarily responsible for moving potassium ions into the cell?​

both the sodium-potassium pump and electrical gradient

The net effect of each cycle of the sodium-potassium pump is to ____.​

decrease the number of positively charged ions within the cell

What action tends to open the sodium gates across a neuron's membrane?​

depolarization of the membrane

The concentration gradient refers to the ____.​

difference in distribution for various ions between the inside and outside of the membrane

The speed of an action potential down an unmyelinated axon is best described as ____.​

faster in thick axons than in thin ones

What occurs when a stimulus shifts the potential inside a neuron from the resting potential to a more negative potential?​

hyperpolarization

Under which conditions would the sodium-potassium pump likely be far less effective in creating a concentration gradient?​

if selective permeability of the membrane did not exist

The function of a myelin sheath is to ____.​

increase the velocity of transmission along an axon


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