Membrane Potentials

Question 1

membrane potential is a __ difference across the plasma membrane

Answer 1

charge

Question 2

membrane potentials are created by unequal distribution of __ and __ across the cell membrane

Answer 2

anions, cations

Question 3

the membrane potential creates __ gradients for movements of ions into/ out of cells

Answer 3

electrical

Question 4

in membrane potentials, charge separation=

Answer 4

source of energy

Question 5

charge difference of membrane when cell is at rest known as

Answer 5

resting membrane potential

Question 6

normal resting vm

Answer 6

-70 mV (negative charge inside cell)

Question 7

the membrane potential opens or closes

Answer 7

gated ion channels

Question 8

the membrane potential regulates

Answer 8

exocytosis

Question 9

two gradients for passive transport of charged substances across the membrane known as

Answer 9

electrochemical gradient

Question 10

what are the two gradients of substance across the membrane (charged)

Answer 10

chemical and electrical

Question 11

FDRion=

Answer 11

(ΔEC)(T)(#ion channels)(P open)

Question 12

when determining between two membrane potential do you determine which one is stronger?

Answer 12

you look at the absolute values

-100mV vs 50mV -100 is stronger cause the absolute value is 100 which is greater than the absolute value of 50 which is 50

Question 13

in chemical gradients ions will move passively down __ gradients

Answer 13

concentration

Question 14

in electrical; gradients ions move passively down __ gradients

Answer 14

electrical

Question 15

with the electrical gradient the charge particles move

Answer 15

toward the opposite charge

Question 16

facilitated diffusion of ions move passively down __ gradient

Answer 16

electrochemical (EC), includes chemical and electrical gradient

Question 17

what will move passively into the cell through
channels down its electrochemical gradient?

Answer 17

Na+

Question 18

strength of the electrical gradient depends on the __ of the ion and the __ of the membrane potential

Answer 18

valence, magnitude

Question 19

Equilibrium Potential (Eion) = Vm that creates an ΔE that is

Answer 19

equal in strength but opposite direction of ΔC

Question 20

ΔE-ΔC=

Answer 20

0

Question 21

with electrochemical equilibrium there is no net ion movement through

Answer 21

channels via facilitated diffusion

Question 22

the nerst equation calculates the equilibrium potential (E) when

Answer 22

ion concentrations are known

Question 23

Eion (mV) =

Answer 23

61/Z log ([ion]ECF / [ion]ICF)
Z=ion valence
61= constant

Question 24

at resting membrane potential K+ chemical gradient is __ the cell

Answer 24

out

Question 25

at resting membrane potential K+ electrical gradient is __ the cell

Answer 25

into

goes toward the negative

Question 26

goes

ΔVm → (chain)

Answer 26

Δelectrical gradient → FDR ion

Question 27

if the elevtrical and chemical gradients are moving in opposite direction you must

Answer 27

solve for the equilibrium potential to determine which one is greater.

Question 28

resting membrane potential for K+

Answer 28

-94 mV

Question 29

at resting membrane potential the equilibrium potential for these ion channels follow their concentration gradient

Answer 29

Na+, K+, Cl-, Ca2+

Question 30

at -70 mV the cell is stimulated and opens __ channels

Answer 30

Na+

Question 31

when Vm becomes less negative than the resting membrane potential

Answer 31

depolarization

Question 32

Vm change that restores resting membrane potential

Answer 32

repolarization

Question 33

Vm becomes more than negative than resting membrane potential

Answer 33

hyperpolarization

Question 34

between depolarization and repolarization Vm __

Answer 34

decreases

Question 35

between hyperpolarization and repolarization Vm __

Answer 35

increases

Question 36

You are given two cells one with a resting potential of -70mV and -100mV. Solve for the membrane equilibrim for K+ and determine the net movement of K+. ETC= 4 ITC= 140

Answer 36

(61/1)log(4/140) =-94

-70mV = out of the cell
-100mV = into the cell

Question 37

You have a cell with a membrane potential of -90mV. What will be the net movement of Cl-. (103 ECF, 4 ICF)

Answer 37

(61/1)log(103/4) =

the net movement will be out

Question 38

in out practice problems which gradients determines the next movement?

Answer 38

the electrical

we are finding out if this is stonger or weaker than the concentration gradient

Question 39

Concentraion is not based on

Answer 39

CHARGE!!!

must memorize direction substances move

Question 40

at resting membrane potential there are way more __ leak channels open than __ channels

Answer 40

K+, Na+

Question 41

Na+/K+ ATPase activity maintains

Answer 41

ΔC for Na+ and K+

Question 42

hyperkalemia is when K+ concentration outside the cell is increased causing

Answer 42

concentration gradient force to be less

Question 43

changing membrane potential also changes

Answer 43

ion permablitiy

Question 44

Resting cell mp is -70mV and K+ equalibrium is -94mV as the membrane potential gets closer to -94mV

Answer 44

the electrical chemical gradient is reduced

Question 45

what are the 2 determinants of the membrane potential?

Answer 45

1. relative ion permabilites
2. Na+ K+ ATPase

Question 46

What are the two things that can change the membrane potential?

Answer 46

1. change membrane permibility (open channels
2. change ion concentrantion

Question 47

since K+ equlibrium is close to the resting is it

Answer 47

highly permable

Question 48

Hypokalemia causes

Answer 48

hyperpolarization

Question 49

hyperkalemia causes

Answer 49

depolarization

K+ does not leave cell and it becomes less negative