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ESA 2- Membranes and Receptors > The Resting Membrane Potential > Flashcards

The Resting Membrane Potential Flashcards

1
Q

What do all cells have?

A

An electrical potential difference (voltage) across their plasma membrane

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2
Q

What does the membrane potential provide?

A

The basis of signalling in the nervous system, as well as in many other types of cells

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3
Q

How is the resting membrane potential expressed?

A

As the potential inside the cell relative to the extracellular solution

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4
Q

What is the membrane potential of animal cells?

A

They have negative membrane potentials, that range from -20 to -90mV

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5
Q

What is the resting potential of nerve cells?

A

-50 to -75mV

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6
Q

What is resting membrane potentials of smooth muscle cells?

A

~ -50mV

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7
Q

What is the resting membrane potential of skeletal and cardiac muscle cells?

A

-80 to -90 mV

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8
Q

What is the cell membrane selectively permeable to?

A

Different ions

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9
Q

How does the permeability of the membrane to ions occur?

A

By way of channel proteins

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10
Q

What makes the whole cell membrane selectively permeable to ions?

A

The selectivity of ion channels and the types of channels that are open

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11
Q

What dominates the membrane ionic permeability at rest for most cells?

A

Open K+ channels

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12
Q

When is there no net movement of K+?

A

When the chemical and electrical gradients for K+ are equal and opposite

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13
Q

What is true when there is no net movement of K+?

A

There will be a negative membrane potential

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14
Q

What does the resting membrane potential arise because of?

A

The membrane being selectively permeable to K+

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15
Q

What is the intracellular concentration of Na?

A

~10mM

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16
Q

What is the extracellular concentration of Na?

A

145mM

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17
Q

What is the intracellular concentration of K?

A

160mM

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18
Q

What is the extracellular concentration of K?

A

4.5mM

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19
Q

What is the intracellular concentration of Cl?

A

4mM

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20
Q

What is the extracellular concentration of Cl?

A

114mM

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21
Q

What is the intracellular concentration of anions (other can Cl)?

A

167mM

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22
Q

What is the extracellular concentration of anions (other than Cl)

A

40mM

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23
Q

What anions other than Cl are involved in the gradient across the cell membrane?

A

Phosphate
Bicarbonate
Amino acids
Charged groups on proteins

24
Q

In what direction is the K concentration gradient?

A

From the inside of the cell to the outside of the cell

25
Q

In what direction is the K electrical gradient?

A

From the outside of the cell to the inside of the cell

26
Q

What is the equilibrium potential for an ion?

A

The membrane potential at which there is no net movement of the ion across the membrane (the concentration gradient = the electrical gradient)

27
Q

What can be used to calculate the equilibrium potential?

A

The Nernst Equation

28
Q

What happens in depolarisation?

A

Membrane potential decreases in size

29
Q

Does depolarisation cause an action potential?

A

Not necessarily- it may only be a few mV

30
Q

What happens to the cell interior in depolarisation?

A

It becomes less negative

31
Q

What causes depolarisation?

A

Opening of Na or Ca channels

32
Q

What happens in hyperpolarisation?

A

The membrane potential increases in size, falling below resting

33
Q

What happens to the cell interior in hyperpolarisation?

A

It becomes more negative

34
Q

What causes hyperpolarisation?

A

Cl or K channels opening

35
Q

What do cells have in reality?

A

Channels open for more than one type of ion

36
Q

What does the contribution of each ion to the membrane potential depend on?

A

How permeable the membrane is to that ion

37
Q

What can change a cells membrane potential?

A

Changes in the cells permeability to a single ion

38
Q

How can be used to cells membrane potential be calculated?

A

The GHK equation

39
Q

What does the GHK equation show?

A

That membrane potential depends on the number of open channels open for each ion

40
Q

Where can synaptic connections occur?

A

Between nerve, muscle, sensory cells and glands

41
Q

How can synaptic transmission be categorised?

A

Into fast and slow

42
Q

What is the receptor protein in fast synaptic transmission?

A

A ion chanel

43
Q

What happens in fast synaptic transmission?

A

The binding of transmitter causes the channel to open

44
Q

What happens in slow synaptic transmission?

A

The receptor protein and ion channel are separate proteins, that may be linked by G-proteins or intracellular messengers

45
Q

What are the two basic patterns of slow synaptic transmission?

A

Direct G-protein gating

Gating via an intracellular messenger

46
Q

What are the characteristics of direct G-protein gating?

A

Localised

Quite rapid

47
Q

How does gating via an intracellular messenger work?

A

The G-protein activates an enzyme, which initiates a signalling cascade, through an intracellular messenger or protein kinase which activates the channel

48
Q

What are the characteristics of gating via an intracellular messenger?

A

Occurs throughout the cell

Amplification by cascade

49
Q

What do excitatory transmitters do?

A

Open ligand-gated channels, causing membrane depolarisations

50
Q

What can ligand-gated channels opened by excitatory transmitters be permeable to?

A

Na, Ca, and sometimes cations in general

51
Q

What is the membrane depolarisation caused by excitatory transmitters called?

A

Excitatory Post-Synaptic Potential (EPSP)

52
Q

How does EPSP differ from an AP?

A

It is graded with the amount of transmitter

53
Q

Give two examples of excitatory transmitters

A

Acetylcholine

Glutamate

54
Q

What do inhibitory transmitters do?

A

Open ligand-gated channels, causing hyperpolarisation

55
Q

What are ligand-gated channels opened by inhibitory transmitters permeable to?

A

K or Cl

56
Q

What is the hyperpolarisation caused by inhibitory transmitters called?

A

Inhibitory post-synaptic potential (IPSP)

57
Q

Give 2 examples of inhibitory transmitters

A

Glycine

γ-aminobutyric acid (GABA)

ESA 2- Membranes and Receptors (13 decks)

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