Trans - Neuronal Excitability I Flashcards

1
Q

cytoskeletal fast transport uses

A

kinesin

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2
Q

cytoskeletal fast retrograde transport uses

A

dynein

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3
Q

special feature of axon hillock

A

large number of Na gates for start of impulse propagation

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4
Q

end of axon

A

terminal bouton

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5
Q

normal resting membrane potential

A

-70 mv at rest

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6
Q

resting membrane potential is mainly influenced by

A
  1. permeability of the membrane for each diffusible ion species
  2. cncentration of ions inside and outside the cell
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7
Q

3 mechanisms to generate RMP

A
  1. transmembrane K gradient through nongated leak channels
  2. Donnan effect.
  3. Na-K pump
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8
Q

main mechanism to generate RMP

A

transmembrane K gradient through nongated leak channels

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9
Q

Na-K pump contributes how much to RMP

A

20%

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10
Q

concentration gradient of K

A

high inside the cell - tends to move out

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11
Q

concentration gradient of Na

A

high outside the cell - tends to move in

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12
Q

concentration gradient of Cl

A

high outside the cell - tends to move in

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13
Q

Gibbs-Donnan equilibirum

A

in the presence of a nondiffusible ion, diffusible ions distribute themselves so that at equilibrium, their concentrations are equal

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14
Q

consequence of Gibbs-Donnan equilibrium

A

differential distribution of diffusible ions when a nondiffusible ion is present

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15
Q

Donnan effect

A

asymmetric distribution of permeant ions at equilibrium resulting in an electrical difference across the cell membrane

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16
Q

Donnan effect - to maintain electrical neutrality, there will always be a (1)______ K concentration inside the cell and a (2)_____Cl concentration outside

A
  1. greater

2. greater

17
Q

side effect of donnan effect

A

accumulation of osmolytes in ICF - corrected by Na-K pump

18
Q

Donnan effect - proteins within the cell limit diffusion of what ion down its concentration gradient

19
Q

Donnan effect - what two forces are created in relation to movement of K

A
  1. force pulling K in –> due to electrical gradient

2. force pulling K out –> due to chemical gradient

20
Q

force that moves solutes

A

diffusion pressure

21
Q

Nernst equation - requirements

A

semipermeable membrane, diffusible species present, electrical and chemical gradient present

22
Q

relationship of diffusion pressure and electrical pressure in equilibrium

23
Q

equilibrium potential of K

A

-90mv - tends to go out

24
Q

equilibrium potential of Na

A

60mv - tends to move in

25
equilibrium potential of Cl
-70mv - does not move (diffusion pressure = electrical pressure)
26
what ion is really responsible for resting membrane potentials? why?
K, because it is freely diffusible at rest (K leak channels)
27
why is the equilibrium potential of K different from the RMP?
Na channels are not completely closed --> small influx of positive ions, bringing the potential up from -90 to -70
28
Goldman Constant Field Equation
takes into consideration all ions involved, used to calculate the true value of RMP
29
why can't the Nernst equation be used to find the value of RMP
Nernst takes into account only one ion; there are many in this system
30
most flux of the 3 major ions
K (high permeability)
31
least flux of the 3 major ions
Cl (does not move)
32
[T/F] resting membrane potential is in absolute equilibrium
F
33
[T/F] resting membrane potential is constant
T
34
with lack of energy from ATP, what will happen to RMP? why?
it will dissipate because the ions are not in absolute equilibrium
35
which ions have almost no contribution to RMP according to the Goldman Equation
Na, Cl
36
action of Na-K pump
3 sodium out, 2 potassium in
37
function of Na-K pump
1. prevent cell swelling | 2. maintain RMP at -70mV
38
[T/F] energy is required to maintain the steady state equilibrium of RMP
T