Practice #5: Map

Front 1

The membrane potential at which there is no net flux of an ion across the membrane is called that ion's ________.

Back 1

equilibrium potential

Front 2

The presence of the ________ prevents the dissipation of the concentration gradient for Na+.

Back 2

Na+/K+ pump

Front 3

Why is the electrical potential of a membrane at rest closest to potassium's equilibrium potential than to sodium's equilibrium potential?

Back 3

more potassium channels are open, allowing more potassium to move out of the cell

Front 4

As a membrane's permeability to a particular ion increases, membrane potential will move ________ that ion's ________.

Back 4

closer to : equilibrium potential

Front 5

True/False: The membrane potential of a cell is determined exclusively by that cell's sodium and potassium permeability.

Back 5

FALSE

Front 6

True/False: The Nernst equation is used to calculate the resting membrane potential.

Back 6

FALSE

Front 7

Whether a membrane is depolarized to threshold or above, the amplitude of the resulting action potential is the same; in other words, once threshold is reached, the action potential will take place. This concept is known as __________.

Back 7

the "all-or-none principle"

Front 8

A change in a cell's membrane potential, such that it becomes more positive, is referred to as a ________.

Back 8

depolarization

Front 9

The depolarization phase of the action potential is generated by a rapid ________.

Back 9

opening of sodium channels

Front 10

The repolarization phase of action potentials in neurons is due primarily to ________.

Back 10

potassium flow out of the cell

Front 11

During which of the following states are the majority of voltage-gated sodium channels closed and incapable of opening?

Back 11

during the absolute refractory period

Front 12

The all-or-none principle, associated with the action potential, states that ________.

Back 12

once membrane potential reaches threshold, an action potential will be generated and that action potential will always be the same magnitude

Front 13

In order for a neuron to move from the absolute to the relative refractory period, a majority of that neuron's sodium channels must have their ________.

Back 13

inactivation gates open

Front 14

In myelinated nerve fibers, where do action potentials occur?

Back 14

nodes of Ranvier

Front 15

True/False: The magnitude of the action potential is dependent upon the extent to which the change in membrane potential is above threshold

Back 15

FALSE

Front 16

Where in the neuron is an action potential initially generated?

Back 16

axon hillock

Front 17

The depolarization phase of an action potential results from the opening of which channels?

Back 17

voltage-gated Na+ channels

Front 18

The repolarization phase of an action potential results from __________.

Back 18

the opening of voltage-gated K+ channels

Front 19

Hyperpolarization results from __________.

Back 19

slow closing of voltage-gated Na+ channels

Front 20

What is the magnitude (amplitude) of an action potential?

Back 20

100 mV

Front 21

The membranes of neurons at rest are very permeable to _____ but only slightly permeable to _____.

Back 21

K+; Na+

Front 22

During depolarization, which gradient(s) move(s) Na+ into the cell?

Back 22

both electrical and chemical gradients

Front 23

What is the value for the resting membrane potential for most neurons?

Back 23

(-70 mV)

Front 24

The Na+–K+ pump actively transports both sodium and potassium ions across the membrane to compensate for their constant leakage. In which direction is each ion pumped?

Back 24

K+ is pumped out of the cell and Na+ is pumped into the cell

Front 25

The concentrations of which two ions are highest outside the cell.

Back 25

Na+ and Cl-