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SfM topics > Nerves 2 > Flashcards

Nerves 2 Flashcards

1
Q

what are the 3 main electrical potentials that exist?

A
  1. action potentials
  2. graded potentials
  3. resting membrane potentials
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2
Q

function of action potentials?

A

send long distance signals along the axon to a distant site

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3
Q

function of graded potentials?

A

decide WHEN an action potential should be fired and if it should be fired

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4
Q

function of resting membrane potential?

A
  • keeps cells always ready to respond to stimulus

- occurs when neurones are sitting still (membrane potential is at rest)

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5
Q

what voltage does resting membrane potential sit at?

A

-70mV

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6
Q

is the cell at RMP (resting membrane potential) negative or positive compared to the outside?

A

negative (outside it’s 0mV)

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7
Q

If ion channels/ pores which are permeable to K only are added, in what direction will K move?

A

Out of the cell (down its concentration gradient) since it’s at high conc. intracellularly (high in ICF and low in ECF)

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8
Q

when is an equilibrium potential established? what is equilibrium potential?

A

membrane potential at which the electrical gradient is exactly equal and opposite to the concentration gradient

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9
Q

what will happen to equilibrium potential and electrical potential if concentration gradient is very high?

A

it will cause a BIGGER electrical potential and equilibrium potential will be HIGHER

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10
Q

what are the 3 terms which link together? (have a clear correlation?)

A
  1. equilibrium potential
  2. concentration gradient
  3. electrical gradient
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11
Q

Due to what part of the cell are cells at RMP?

A

due to leaky K channels which are always open at rest (permeable)

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12
Q

what is the role in equilibrium potential an concentration gradient in K movement?

A
  • conc. gradient is pushing K out

- equilibrium potential/electrical gradient is drawing K back in

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13
Q

when is a big resting potential formed?

A

when there is a big conc. gradient and lot of K flows out of the cell

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14
Q

when is a small resting potential formed?

A

when there is a small conc. gradient and less K flows out of the cell

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15
Q

what determines equilibrium potential?

A

concentration gradient

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16
Q

what equation predicts equilibrium potential for a SINGLE ion species?

A

Nernst equation

17
Q

what prevents high levels of K affecting our brain?

A

blood brain barrier

18
Q

describe what happens when a banana is eaten (high in K)

A
  1. banana eaten and levels of K in ECF rise
  2. conc. gradient is reduced
  3. this sustains a smaller electrical gradient at equilibrium
  4. RMP is reduced/stops/decreased (cell depolarises)
19
Q

what does blood brain barrier do?

A

protects the brain from changes in K concentration in the plasma. Heart does not have this mechanism

20
Q

what structures are fundamental in blood brain barrier?

A
  • tight capillaries
  • astrocytes
  • tight junctions in the endothelial cells
21
Q

why is RMP at -70mV?

A

due to other leaky channels such as Na or Cl

22
Q

where are concentrations of K high?

A

in ICF

23
Q

where are concentrations of Na and Cl high

A

in ECF

24
Q

Why do Na and Cl leaky channels have a smaller effect on RMP compared to K channels?

A

because their permeability is lower whereas RMP is close to K equilibrium

25
Q

What does the Na/K pump establish?

A

concentration gradient

26
Q

what equation predicts equilibrium potential generated by SEVERAL ions?

A

Goldman equation

27
Q

what happens if more K channels are opened?

A

more K flows out and cell hyperpolarises (more negative)

28
Q

what happens if more Na channels are opened?

A

more Na flows in and cell depolarises (more positive)

29
Q

what happens if more Cl channels are opened?

A

more Cl flows in and cell hyperpolarises (more negative)

30
Q

what happens if more Ca channels are opened?

A

more Ca will flow in and cell depolarises (more positive)

31
Q

what is the special characteristic of Ca ions?

A

they can travel in both directions

32
Q

is Ca involved in RMP?

A

no, not at all

33
Q

what happens to cell at depolarisation

A

becomes more POSITIVE ( mV approaches 0)

34
Q

what happens to cell at hyperpolarisation?

A

becomes more NEGATIVE (mV goes below RMP)

35
Q

what happens to cell at overshoot?

A

mV goes way above 0mV

36
Q

what happens to cell at repolarising?

A

cell’s mV travels from overshoot back down to RMP

37
Q

if K travels into the cell naturally (2Kin) why is it moving out?

A

due to concentration gradient (moves down/ along it), from high conc. in ICF to low conc. in ECF)

SfM topics (21 decks)

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