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Foundations of Neuroscience > Membranes and cell excitation > Flashcards

Membranes and cell excitation Flashcards

1
Q

An electrical signal involves…

A

…a change in the balance of positive and negative charges

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2
Q

Name 5 important charged particles

A

Na+, K+, Cl-, Ca2+ and protein side chains

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3
Q

What controls ion movement inside and outside of a cell?

A

The membrane

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4
Q

What generates an electrical signal?

A

The transfer of ions through ion channels

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5
Q

What maintains gradients?

A

Ion pumps

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6
Q

Describe lipid bilayer permeability

A

Impermeable to most molecules, including ions

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7
Q

The inside of a cell contains…

A

….an excess of anions

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8
Q

What is the voltage inside the cell called?

A

Membrane potential (Em)

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9
Q

What is the membrane potential of a neurone?

A

-65mV

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10
Q

What determines membrane potential?

A

The balance of charges

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11
Q

Ion movement is…

A

…passive

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12
Q

Which ion channels are permeant?

A

Na+, K+, Ca2+, Cl-

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13
Q

Why are membrane proteins essential?

A

They control membrane potential

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14
Q

Name the three types of gated channels

A

Non-gated, voltage, ligand

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15
Q

What are non-gated channels also known as?

A

Leak channels

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16
Q

What do voltage-gated channels do?

A

Generate action potentials

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17
Q

What do ligand-gated channels do?

A

Generate membrane potential changes at synapses

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18
Q

Neurones are _____ cells

A

Excitable cells

19
Q

Neurones have a resting membrane potential of…

A

…-60mV to -70mV

20
Q

What factors influence ion movement across the cell membrane?

A

Unequal ion distribution and electrical force

21
Q

What does the permeability of the membrane tell us?

A

How easily an ion moves across the membrane (via ion channels)

22
Q

What do efflux and influx mean?

A 
Efflux = movement out
Influx = movement in
23
Q

Define equilibrium

A

An ion is in equilibrium when chemical gradient and electrical force are in balance

24
Q

What is equilibrium potential abbreviated to?

A

Eion

25
Q

What does the Nernst equation do?

A

Defines the voltage at which the ion is at equilibrium

26
Q

What is happening at equilibrium potential?

A

The amount of efflux = influx

27
Q

What is different between Eion and Em

A

Eion is a constant, Em can vary

28
Q

What is ionic driving force?

A

Em - Eion

29
Q

Explain ionic driving force

A

What drives the ion across the membrane when Em is not equal to Eion

30
Q

Is ionic driving force proportional?

A

Yes

31
Q

In a neurone, what influences Em?

A

Na+ and K+

32
Q

Em rests between what?

A

EK and ENa

33
Q

How do we calculate Em?

A

The Goldman equation

34
Q

What is Em dependent on?

A

Relative permeabilities (Pion)

35
Q

Compare the relative permeabilities of Na and K

A

PK is 40x bigger than PNa

36
Q

Why is Em closer to EK?

A

Because of the difference in permeabilities

37
Q

What is happening at -65mV in a neurone?

A

Driving force acting on both Na+ and K+
Na+ influx
K+ efflux

38
Q

What is making Na+ move in?

A

Chemical gradient and electrical force

39
Q

What is making K+ move out?

A

Chemical gradient, but electrical force is making K+ move in

40
Q

What ensures Em of -65mV is at rest?

A

Na+ influx = K+ efflux

41
Q

Compare the driving force of Na+ and K+

A 
Na+ = large
K+ = small
42
Q

Compare the permeability to Na+ and K+

A 
Na+ = small
K+ = large
43
Q

Do ion pumps control Em?

A

No, they maintain concentration in the long term

44
Q

What does the sodium-potassium pump do?

A

Exchanges internal Na+ for external K+

against concentration gradient

Foundations of Neuroscience (15 decks)

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