Dr. Karius' Vm lecture Flashcards

1
Q

Resting membrane potential of all living cells is

A

lower than outside

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2
Q

Vm is the

A

difference of electrical potential between inside and outside cell and right at the membrane itself

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3
Q

if a cell’s Vm is 0 that means there is

A

no difference between the inside and the outside of the cell

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4
Q

-90 and +90 Vm mean

A

the two charges are equal in magnitude but opposite in polarity

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5
Q

hyperpolarization =

A

the membrane potential becomes more negative (moves farther away from zero)

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6
Q

Depolarization =

A

the membrane potential becomes less negative (moves closer to zero)

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7
Q

an ionic gradient exists when two conditions are met

A

1) there is an electrical gradient and

2) there is a chemical gradient working a particle

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8
Q

an ionic equilibrium may be achieved when

A

the combined forces of the concentration gradient and the electrical gradient are balanced, even if on their own they do not appear to be balanced

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9
Q

Two things are required to make an ionic gradient

A

a selectively permeable membrane and a Na/K ATPase

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10
Q

Lipophilic–Hydrophilic Polar–Non polar: which of the three can passively diffuse across a membrane?

A

the lipophilic and the nonpolar

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11
Q

Na+ =

A

low permeability

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12
Q

K+ =

A

higher permeability at rest (100X of sodium)

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13
Q

Ca++

A

low permeability at ret

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14
Q

Cl-

A

moderate permeability at rest

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15
Q

intracellular proteins have what kind of charge?

A

negative

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16
Q

proteins create a

A

electrical gradient because they are negatively charges

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17
Q

negative ions outside the cell are

A

repelled because of the net negative charge inside the cell, so positive charges are attracted

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18
Q

What are the TWO ways a selective permeability helps create the membrane potential

A

1) by keeping the proteins (with their negative charges) in the cell
2) by not allowing certain ions (e.g. sodium) to enter the cell

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19
Q

the Na/K ATPase pumps out more

A

+ from than into the cell (3Na out, 2K in)

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20
Q

what is the Na/K ATPase described as?

A

electrogenic

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21
Q

Sodium is higher

A

outside the cell than inside

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22
Q

Potassium is higher

A

inside the cell than outside

23
Q

Chloride is higher

A

outside the cell than inside

24
Q

Calcium is higher

A

outside the cell than inside

25
electrogenic means the cell
pumps out more (+) than (-)
26
the most important role of the Na/K ATPase is
producing a concentration gradient
27
what happens if you poison the Na/K pump?
the cell depolarizes immediately because of the loss of electrogenic effect of the ATPase, then more slowelr because the concentration gradient begins to equalize
28
how much voltage in a neuron is lost if you poison the Na/K pump?
around 5 mV
29
what is a chemical expression of electrogenicity?
3Na/2K
30
Effect on cell if Na/Ka is poisoned: initial and final
cell death 1) initial 5-10 mV 2) slower depolarization to 0
31
Importance of electrogenicity and Na/K in what cells?
neurons, skeletal muscle CRITICAL | other cells types not as critical
32
part 1: proteins do what
attract positive (K) ions to the interior of the cell
33
part 2: Na/K does what
pumps out 3 Na for every 2 K it pumps it takes in
34
part 3: the membrane doesn't allow ____ to cross the membrane readily
ions
35
Muscle cells have a resting Vm is
-70 mv to -90 mv
36
the electrical and chemical gradient of Na
e: pulls Na into the cell c: pulls Na into the cell
37
the electrical and chemical gradient of K
e: pulls K into the cell c: repels K from the cell
38
the electrical and chemical gradient of Cl
e: repels Cl c: attracts Cl
39
the electrical and chemical gradient of Ca
e: attracts Ca c: attracts Ca
40
What happens if the Nernst potential is more negative than the membrane potential?
ions will move out of the cell
41
what happens if the nernst potential is less negative than the membrane potential?
ions will move from the outside to the inside
42
what happens if the nernst potential is equivalent to the membrane potential?
nothing moves because the electrical gradient and the chemical gradient are equal in opposite directions
43
At normal conditions, the equilibrium potential is ____ than the membrane potential
less than
44
if Vm is less negative than the equilibrium value, which direction does the gradient go?
out of the cell
45
if the Vm is more negative than the equilibrium value, which direction does the gradient go?
into the cell
46
V (DF) = Vm - Veq
DF is driving force driving force = membrane potential minus nernst (equilibrium potential)
47
results of Vm larger than Veq?
cation OUTWARD flow; anion inward flow Ved is positive
48
result when Vm is smaller than Veq?
cation inward flow, anion outward flow Ved is negative
49
Vm = Veq ?
no net flow in either direction
50
What happens when the depolarization voltage nears V(Na) ?
The potassium channels are activated
51
Does the V(Na) ever get achieved?
no, just below it
52
What happens when hyperpolarization voltage nears V(k)?
V begins to depolarize slightly until it arrives at Vrest (Vm)
53
Does hyperpolarization ever reach Vk?
no
54
Hey now
Does this work?