Membrane Potential (session 4)

Question 1

Which cells have the largest resting potentials? (2)

Answer 1

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

Question 2

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

Answer 2

Asymmetric distribution of ions across the plasma membrane

Selective ion channels in the plasma membrane

Question 3

What dominates the resting membrane permeability?

Answer 3

Open K+ channels

Question 4

What is depolarisation?

Answer 4

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

Question 5

What is hyperpolarisation?

Answer 5

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

Question 6

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

Answer 6

-95mV

Question 7

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

Answer 7

+70mV

Question 8

What is the equilibrium potential of Cl-?

Answer 8

-96mV

Question 9

What is the equilibrium potential of Ca2+?

Answer 9

+122mV

Question 10

The opening of which channels causes hyperpolarisation?

Answer 10

K+ or Cl-

Question 11

The opening of which channels causes depolarisation?

Answer 11

Na+ or Ca2+

Question 12

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

Answer 12

TRUE

Question 13

When do ligand-gated channels open?

Answer 13

In response to the binding of a chemical ligand

Question 14

When do voltage-gated channels open?

Answer 14

In response to changes in membrane potential

Question 15

When do mechanical-gated channels open?

Answer 15

In response to membrane deformation

Question 16

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

Answer 16

TRUE

Question 17

What do excitatory transmitters do?

Answer 17

Open ligand-gated channels that cause membrane depolarisation

Question 18

What does EPSP stand for and what is it?

Answer 18

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

Question 19

What are the features of an EPSP? (2)

Answer 19

Longer time course than action potential

Graded with amount of transmitter

Question 20

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

Answer 20

ACh
Glutamate
Dopamine

Question 21

What do inhibitory transmitters do?

Answer 21

Open ligand-gated channels that cause hyperpolarisation

Question 22

Which ions are excitatory synapses permeable to?

Answer 22

Na+ and Ca2+

Question 23

Which ions are inhibitory synapses permeable to?

Answer 23

K+ and Cl-

Question 24

Which transmitters are used in inhibitory synapses? (2)

Answer 24

Glycine

Gamma-aminobutyric acid (GABA)

Question 25

Which other two factors can influence the membrane potential?

Answer 25

Changes in ion concentration | Electrogenic pumps

Question 26

Define membrane potential

Answer 26

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

Question 27

What is [K+]o?

Answer 27

4.5mM

Question 28

What is [K+]i?

Answer 28

160mM

Question 29

What is the difference between fast and slow synaptic transmission?

Answer 29

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

Question 30

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

Answer 30

Localised | Quite rapid