Membrane Potential (session 4) Flashcards

1
Q

Which cells have the largest resting potentials? (2)

A

Cardiac and skeletal muscle cells (-80 to -95 mV)

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2
Q

Which two factors are important for the generation of a membrane potential?

A

Asymmetric distribution of ions across the plasma membrane

Selective ion channels in the plasma membrane

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3
Q

What dominates the resting membrane permeability?

A

Open K+ channels

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4
Q

What is depolarisation?

A

Decrease in size of membrane potential from its normal value, cell interior becomes less negative (-70mV to -50mV)

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5
Q

What is hyperpolarisation?

A

Increase in size of membrane potential from its normal value, cell interior becomes more negative (-70mV to -90mV)

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6
Q

What is the equilibrium potential of K+? (Ek)

A

-95mV

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7
Q

What is the equilibrium potential of Na+? (ENa)

A

+70mV

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8
Q

What is the equilibrium potential of Cl-?

A

-96mV

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9
Q

What is the equilibrium potential of Ca2+?

A

+122mV

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10
Q

The opening of which channels causes hyperpolarisation?

A

K+ or Cl-

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11
Q

The opening of which channels causes depolarisation?

A

Na+ or Ca2+

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12
Q

True or false: nicotinic acetylcholine receptors open by binding to ACh

A

TRUE

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13
Q

When do ligand-gated channels open?

A

In response to the binding of a chemical ligand

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14
Q

When do voltage-gated channels open?

A

In response to changes in membrane potential

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15
Q

When do mechanical-gated channels open?

A

In response to membrane deformation

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16
Q

True or false: in fast synaptic transmission, receptor proteins are also ion channels

A

TRUE

17
Q

What do excitatory transmitters do?

A

Open ligand-gated channels that cause membrane depolarisation

18
Q

What does EPSP stand for and what is it?

A

Excitatory post-synaptic potential - Change in membrane potential at a excitatory synapse

19
Q

What are the features of an EPSP? (2)

A

Longer time course than action potential

Graded with amount of transmitter

20
Q

Which transmitters are used in an excitatory synapse? (3)

A

ACh
Glutamate
Dopamine

21
Q

What do inhibitory transmitters do?

A

Open ligand-gated channels that cause hyperpolarisation

22
Q

Which ions are excitatory synapses permeable to?

A

Na+ and Ca2+

23
Q

Which ions are inhibitory synapses permeable to?

A

K+ and Cl-

24
Q

Which transmitters are used in inhibitory synapses? (2)

A

Glycine

Gamma-aminobutyric acid (GABA)

25
Q

Which other two factors can influence the membrane potential?

A

Changes in ion concentration

Electrogenic pumps

26
Q

Define membrane potential

A

Magnitude of electrical charge that exists across a plasma membrane and is always expressed as a potential inside the cell relative to the extracellular solution

27
Q

What is [K+]o?

A

4.5mM

28
Q

What is [K+]i?

A

160mM

29
Q

What is the difference between fast and slow synaptic transmission?

A

In fast, the receptor protein is also an ion channel whereas in slow, the receptor and channel are separate proteins

30
Q

What are the features of direct G-protein gating? (2)

A

Localised

Quite rapid