Electrophysiology

Question 1

Ion channels: _________ proteins that span the membrane and, when open, permit the passage of certain ions

Answer 1

integral

Question 2

Ion channels are _______; they permit the passage of some ions, but not others.

Answer 2

selective

Question 3

the higher the probability that a channel is open, the higher the _____________, or permeability.

Answer 3

conductance

Question 4

ligand-gated channels open and close in response to a specific ____________ (ligand) including neurotransmitters, hormones and particular ions

Answer 4

chemical stimulus

Question 5

the _______ receptor for acetylcholine (ACh) at the motor end plate is an ion channel that opens when ACh binds to it.

Answer 5

nicotinic

Question 6

these are ion channels that are always open

Answer 6

Leakage channels

Question 7

the membrane’s permeability for potassium is much ________ than it is for sodium

Answer 7

higher

Question 8

mechanically gated channels opens and closes in response to ___________ in the form of vibration (sound waves), pressure (touch) or tissue stretching.

Answer 8

mechanical stimulation

Question 9

voltage gated channels opens in response to a change in ______________ (voltage)

Answer 9

membrane potential

Question 10

it is a process wherein the cell interior becomes less negative due to influx of cations

Answer 10

depolarization

Question 11

its is a process wherein the cell interior becomes more negative due to influx of anions

Answer 11

hyperpolarization

Question 12

it refers to the number of channels that are open in a membrane; it increases when channels are opening, and it decreases when channels are closing

Answer 12

conductance

Question 13

it is a force determined by the concentration difference across the membrane

Answer 13

concentration force

Question 14

a force determined by the electrical difference across the membrane (membrane potential)

Answer 14

electrical force

Question 15

At EQUILIBRIUM, these two forces are always equal
but opposite in direction

Answer 15

concentration and electrical

Question 16

[Action potential]

the voltage-gated sodium channel is closed and not capable of opening (___________) when the membrane’s from peak to resting potential (+30 mV to -70 mV)

Answer 16

inactivated

Question 17

[Action potential]

the voltage-gated sodium channel is open (________) when the membrane potential is from threshold to peak potential (-50 mV to +30 mV)

Answer 17

activated

Question 18

[Action potential]

the voltage-gated sodium channel is ________ but capable of opening when the membrane potential is at resting potential (-70 mV)

Answer 18

closed

Question 19

It is the potential difference generated across a membrane because of a concentration difference of an ion. It is generated only if the membrane is permeable to the ion

Answer 19

Diffusion potential

Question 20

At _________________, the chemical and electrical driving forces that act on an ion are equal and opposite, and no further net diffusion of the ion occurs

Answer 20

electrochemical equilibrium

Question 21

It is used to calculate the ion’s equilibrium potential at a given concentration gradient

Answer 21

Nernst equation

Question 22

Nernst equation for ions with single charge (e.g. Na +)

Answer 22

Vm = 61.5 x LOG ([ion]out / [ion] in)

Question 23

Nernst equation for ions with double charge (e.g. Ca 2+)

Answer 23

Vm = 30.75 x LOG ([ion]out / [ion] in)

Question 24

Approximate value for Na + equilibrium potential (in nerve & skeletal muscle)?

Answer 24

+65 mV

Question 25

Approximate value for Ca 2+ equilibrium potential (in nerve & skeletal muscle)?

Answer 25

+120 mV

Question 26

Approximate value for K+ equilibrium potential (in nerve & skeletal muscle)?

Answer 26

-85 mV

Question 27

Approximate value for Cl- equilibrium potential (in nerve & skeletal muscle)?

Answer 27

-85 mV

Question 28

The flux of ungated K+ channels must be an __________ from the cell

Answer 28

EFFLUX

Question 29

___________ happens when there's too much potassium in the blood, reducing the efflux of K+ and further depolarizing the cell

Answer 29

Hyperkalemia

Question 30

_________ can accelerate the efflux of K+, hyperpolarizing the cell

Answer 30

Hypokalemia

Question 31

A CELL’S RESTING MEMBRANE POTENTIAL IS VERY __________ TO CHANGES IN THE EXTRACELLULAR POTASSIUM CONCENTRATION

Answer 31

SENSITIVE

Question 32

A CELL’S RESTING MEMBRANE POTENTIAL IS ______________ TO CHANGES IN THE EXTRACELLULAR SODIUM CONCENTRATION

Answer 32

NOT SENSITIVE

Question 33

property of excitable cells (i.e., nerve, muscle) that consists of a rapid depolarization, or upstroke, followed by repolarization of the membrane potential. It is propagating and an "all-or-none" process.

Answer 33

Action potential

Question 34

______ membrane potential is the result of the high resting conductance to K+, which drives the membrane potential toward the K+ equilibrium potential.

Answer 34

Resting

Question 35

The __________ is the brief portion at the peak of the action potential when the membrane potential is positive

Answer 35

overshoot

Question 36

__________ block these voltage-sensitive Na+ channels and abolish action potentials

Answer 36

Tetrodotoxin (TTX)

Question 37

_________ blocks voltage-gated K+ channels.

Answer 37

Tetraethylammonium (TEA)

Question 38

the period during which another action potential cannot be elicited, no matter how large the stimulus.

Answer 38

Absolute Refractory Period

Question 39

period that begins at the end of the absolute refractory period and continues until the membrane potential returns to the resting level.

Answer 39

Relative Refractory Period

Question 40

occurs when the cell membrane is held at a depolarized level such that the threshold potential is passed without firing an action potential.

Answer 40

Accomodation

Question 41

_________ of action potentials occurs by the spread of local currents to adjacent areas of membrane, which are then depolarized to threshold and generate action potentials

Answer 41

Propagation

Question 42

__________ acts as an insulator around nerve axons and increases conduction velocity. Myelinated nerves exhibit saltatory conduction because action potentials can be generated only at the _________

Answer 42

Myelin, nodes of Ranvier

Question 43

What happens during the upstroke of the nerve action potential? (A) there is net outward current and the cell interior becomes more negative (B) there is net outward current and the cell interior becomes less negative (C) there is net inward current and the cell interior becomes more negative (D) there is net inward current and the cell interior becomes less negative

Answer 43

D

Question 44

The neurotoxin purified from the liver of a puffer fish affects which process? A. Inhibits calcium channel B. Opens sodium channel C. Opens calcium channel D. Blocks sodium channel

Answer 44

D

Question 45

A channel lined with negatively charged groups will be selective for these ions A. Sodium ions B. Calcium ions C. Chloride ions D. Phosphate ions

Answer 45

Both A & B