The Resting Membrane Potential

Question 0

How is the RMP expressed?

Answer 0

The voltage inside relative to the outside

Question 1

What is a membrane potential?

Answer 1

An electrical potential difference across a cell’s plasma membrane

Question 2

What is the RMP range for a nerve cell?

Answer 2

-50 - -90mV

Question 3

What is the main ion involved in setting up the RMP?

Answer 3

K+

Question 4

When potassium channels are open, in which direction does potassium move?

Answer 4

Out of the cell, down its concentration gradient

Question 5

What are the intracellular and extracellular concentrations of potassium?

Answer 5

Intracellular: 160mM
Extracellular: 4.5mM

Question 6

What does the Nernst equation calculate?

Answer 6

The equilibrium potential of an ion

Question 7

How is the equilibrium potential of potassium (Ek) reached in a resting cell membrane? (Imagine there are no other ions involved)

Answer 7

Potassium channels are open so potassium diffuses out down its concentration gradient
This makes the cell negative and this opposes outflow of K+
Some potassium moves back in until an equilibrium is reached (Ek)
This potential difference is the the Ek

Question 8

Is the resting membrane potential more or less negative than Ek?

Answer 8

Less negative

Question 9

What effect does increasing the concentration of potassium extracellulary have on the RMP?

Answer 9

Makes it more positive

Question 10

Define depolarisation

Answer 10

Decease in membrane potential so that inside the cell becomes less negative

Question 11

Define hyperpolarisation

Answer 11

An increase in membrane potential so that inside the cell becomes more negative.

Question 12

Which ions have a positive equilibrium potential and which have a negative one?

Answer 12

Positive: Na and Ca
Negative: K and Cl

Question 13

Opening Na or Ca will hyperpolarise or depolarise the RMP?

Answer 13

Depolarise

Question 14

What is mechanical gating?

Answer 14

When an ion channel opens/closes in response to membrane deformation

Question 15

What can the membrane potential be measured by?

Answer 15

A microelectrode

Question 16

What can the resting potential of an animal cell be in the range of?

Answer 16

-20 to -90mV

Question 17

What can the resting potential of a cardiac/muscle cell be in the range of?

Answer 17

-80 to -90mV

Question 18

How does increasing the permeability of an ion affect the RMP?

Answer 18

It moves it closer to the equilibrium potential of that ion

Question 19

What is the equilibrium potential of an ion?

Answer 19

The membrane potential at which there is no net movement of the ion across the membrane

Question 20

What is the difference between fast and slow synaptic transmission?

Answer 20

Fast synaptic transmission - the receptor protein is also an ion channel. The binding of the transmitter causes the channel to open.

Slow synaptic transmission - the receptor protein and ion channel are separate proteins. May be linked by G proteins or intracellular messengers

Question 21

Name some transmitters at excitatory synapses

Answer 21

Acetylcholine

Glutamate

Question 22

Name some neurotransmitters at inhibitory synopses

Answer 22

Glycine

γ-aminobutyric acid (GABA)

Question 23

What do excitatory synapses cause?

Answer 23

Membrane depolarisation

An excitatory post synaptic potential (EPSP)

Question 24

What do inhibitory synapses cause?

Answer 24

Hyperpolarisation

Inhibitory post synaptic potential

Question 25

Which protein is the most important in allowing ionic movement to establish RMP?

Answer 25

Voltage-insensitive potassium channels

Question 26

In hyperkalaemia, does the RMP become more positive or negative?

Answer 26

Positive

Question 27

In hyperkalaemia, is it harder or easier for an action potential to be fired?

Answer 27

Easier because the RMP is closer to the threshold

Question 28

Activation of the glycine receptor results in membrane hyperpolarisation or depolarisation?

Answer 28

Hyperpolarisation

Question 29

Which ion is the glycine receptor permeable to?

Answer 29

Chloride

Question 30

Inhibitory postsynaptic potentials may be elicited by opening channels for which ions?

Answer 30

Potassium and chloride

Question 31

Excitatory postsynaptic potentials may be elicited by opening channels for which ions?

Answer 31

Sodium and calcium