Resting Membrane Potential

Question 1

normal potassium concentrations in and out of the cell

- which is higher which is lower

Answer 1

out: ~5 mM
in: ~150 mM

ratio of out/in: 1:30

Question 2

normal sodium concentrations in and out of the cell

- which is higher which is lower

Answer 2

out: ~150 mM
in: ~12 mM

ratio of out/in: 10:1

Question 3

what channels have the greatest influence on resting membrane potential

Answer 3

potassium leak channels

Question 4

what channels have a small influence on resting membrane potential

Answer 4

sodium-potassium ATPase

Question 5

resting membrane potential is primarily due to permeability of the plasma membrane to _____ ions

Answer 5

potassium

Question 6

the membrane is permeable somewhat to potassium, but not as much to ____ and _____

Answer 6

sodium and calcium

Question 7

role of Na+/K+ ATPase

Answer 7

exchange 3 Na+ ions to outside of cell and bring 2 K+ ions into the cell

• maintains concentrations
• requires ATP

Question 8

potassium leak channels

Answer 8

open all the time; permit mostly unregulated passage of ions

- present in a 100:1 ratio to Na+ leak channels

Question 9

resting membrane potential of muscle (cardiac/skeletal) cells

Answer 9

-80 mV to -90 mV

Question 10

resting membrane potential of smooth muscle cells

Answer 10

-60 mV

Question 11

resting membrane potential of neuron cells

Answer 11

-60 mV to -70 mV

Question 12

equilibrium potential

Answer 12

membrane potential when electrical and chemical forces are equal, no further movement occurs
(is not the same as resting membrane potential)

Question 13

electrochemical forces

Answer 13

diffusion forces + electrical forces

Question 14

driving force

Answer 14

resting membrane potential - equilibrium potential of an ion

- takes into account electrical and chemical forces to predict movement of ions

Question 15

when [ion]in is greater than [ion]out, the log will be ____

Answer 15

negative

Question 16

when [ion]in is less than [ion]out, the log will be _____

Answer 16

positive

Question 17

when [ion]in is equal to [ion] out, the log will be _____

Answer 17

zero

Question 18

if the driving force for potassium ions is positive, there will be a net ____ of ions

Answer 18

efflux

Question 19

if the driving force for potassium ions is negative, there will be a net ____ of ions

Answer 19

influx

Question 20

if the driving force for sodium ions is negative, why is there not an influx of ions?

Answer 20

sodium ions need a signal in order to influx into the cell; at resting they will not enter themselves

Question 21

normal calcium concentrations in and out of cell

Answer 21

out: 2 mM
in: 0.0002 mM

ratio of out/in: 10,000:1

Question 22

normal chlorine concentrations in and out of cell

Answer 22

out: 120 mM
in: 10 mM

ratio of out/in: 12:1

Question 23

normal protein (-) concentrations in and out of cell

Answer 23

out: 0.2 mV
in: 100 mV

ratio of out/in: 1:5,000

Question 24

with an equilibrium potential of -91 mV, what is the permeability of potassium leaving the cell

Answer 24

80-85%

Question 25

with an equilibrium potential of +66 mV, what is the permeability of sodium entering the cell

Answer 25

1-2%

Question 26

with an equilibrium potential of +123 mV, what is the permeability of calcium entering the cell

Answer 26

1%

Question 27

with an equilibrium potential of -66 mV, what is the permeability of chlorine leaving the cell

Answer 27

10-12%

Question 28

____ diffusion potential is the main contributor to resting membrane potential

Answer 28

potassium

Question 29

what is the contribution of Na+ diffusion to resting membrane potential

Answer 29

minimal due to low permeability at rest; 5 mV positive contribution

Question 30

what is the contribution of Na+-K+ ATP pump to resting membrane potential

Answer 30

minimal direct contribution; 4 mV negative contribution

Question 31

as extracellular potassium concentration increases, resting membrane potential _____

Answer 31

becomes more positive

Question 32

as extracellular potassium concentration decreases, resting membrane potential _____

Answer 32

becomes more negative

Question 33

general equilibrium potential of potassium (K+)

Answer 33

~ -90 mV

Question 34

general equilibrium potential of sodium (Na+)

Answer 34

~ +60 mV

Question 35

general equilibrium potential of calcium (Ca2+)

Answer 35

~ 120 mV

Question 36

general equilibrium potential of chlorine (Cl-)

Answer 36

~ -65 mV