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Physiology I > RMP & Excitability > Flashcards

RMP & Excitability Flashcards

1
Q

Define resting membrane potential

A

difference in electrical potential across cell membrane

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2
Q

because membrane potentials are expressed relative to extracellular fluid, when membrane potential is negative it means

A

inside of cell more negative than outside of cell

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3
Q

what is responsible for the majority of the resting membrane potential

A

K+ and Na+ flowing through leak (non-gated) channels

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4
Q

how much does the sodium potassium pump contribute to RMP

A

-4mV

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5
Q

how does the sodium potassium pump contribute -4mV to RMP

A

net positive charge outside of cell, 3 sodium out for every two potassium in

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6
Q

what is the purpose of the goldman-hodgkin-katz equation?

A

the influence of K+, Na+, and Cl- on the membrane potential

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7
Q

what does P stand for in goldman equation

A

permeability of the membrane

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8
Q

what does o and i stand for in goldman equation

A

i is inside the membrane

o is outside the membrane

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9
Q

write out the goldman-hodgkin-katz equation

A

pg 6

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10
Q

if one ion’s permeability becomes greater than anothers, what happens

A

for that ion the membrane potential approaches equilibrium

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11
Q

usually, how much greater is permeability for potassuim than sodium

A

20-25

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12
Q

why doesn’t chlorine ions contribute significantly to resting membrane potential?

A

resting membrane potential for the cell is almost identical to equilibrium potential for chlorine

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13
Q

a 10 fold concentration change in extracellular K+ will change RMP by what

A

60 mV

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14
Q

why wouldn’t a 10 fold concentration in extracellular Na+ change RMP by 60 mV?

A

permeability of Na to K is MUCH smaller (1:20-25)

so it would have little to no affect on membrane potential

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15
Q

what is conductance

A

the ability of a given ion species to carry electrical current across the membrane

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16
Q

what does conductance depend on

A

permeability and concentration

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17
Q

what is purpose of ohm’s law

A

can predict amplitude of ion fluxes

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18
Q

what relationships does ohm’s law specify

A

current, electromotive force, conductance

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19
Q

what is current

A

flux of charge carriers

20
Q

what is electromotive force

A

force that drives the fluxes

21
Q

write out ohm’s law

A

V = IR

22
Q

state what variables stand for in Ohm’s law

A 
V = voltage
I = electrical current
R = resistance
23
Q

if there is high resistance, what happens to conductance

A

low conductance

24
Q

if there is low resistance, what happens to conductance

A

high conductance

25
Q

what does gion stand for

A

conductance

26
Q

Iion stands for?

A

electrical current carried by ion

27
Q

Iion =? (give equation)

A

Iion = gion (Vm - Eion)

28
Q

Vm stands for

A

membrane potential

29
Q

what is depolarization

A

membrane potential is less negative than resting potential (more positive)

30
Q

what is hyperpolarization

A

membrane potential is more negative than resting potential

31
Q

at resting potential what are voltage gated channels doing

A

they are closed

32
Q

leak channels for potassium and sodium generate

A

resting membrane potential

33
Q

are channels besides leak involved in generating resting membrane potential

A

no

34
Q

more positive is

A

depolarization

35
Q

more negative is

A

hyperpolarization

36
Q

resting potential of a myelinated neuron fiber is primarily dependent on concentration of which ion?

A

K+

37
Q

To calculate conductance what equation do you have to use

A

Ohm’as law

V=IR

38
Q

magnitude of current when you’re not at equilibrium potential for ion, use

A

ohm’s law

39
Q

when you’re at equilibrium potential what is current

A

0

40
Q

voltage clamp to -89 the cell what does it mean

A

make -89 relative to outside the cell

41
Q

anything below x axis is

A

inward current, negative number

42
Q

anything above x axis is

A

outward current, positive number

43
Q

Vm is where on a x y graph

A

x axis

44
Q

I (current) is where on a x y graph

A

y axis

45
Q

what happens excitability in depolarization

A

more excitability

46
Q

what happens to excitability in hyperpolarization

A

less excitability

Physiology I (9 decks)

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