lecture 3: membrane potentials

Question 1

what is the membrane potential caused by?

Answer 1

the impermeability of the lipid bilayer to charged molecules

Question 2

what is meant by the equilibrium potential?

Answer 2

the balance of diffusional and electrical forces

Question 3

why is the membrane potential around -70mV?

Answer 3

because the membrane is more permeable to K, so the potential closely resembles Ek

Question 4

what is meant by depolarisation?

Answer 4

decrease in the size of the membrane potential, cell interior becomes more negative

Question 5

what is meant by hyperpolarisation?

Answer 5

increase in the size of the membrane potential, cell interior becomes more positive

Question 6

opening which channels causes depolarisation?

Answer 6

K+ or Cl-

Question 7

opening which channels causes hyperpolarisation?

Answer 7

Ca2+ or Na+

Question 8

what do excitatory synapses do?

Answer 8

open ligand-gated channels that cause depolarisation

Question 9

what do inhibitory synapses do?

Answer 9

open ligand-gated ion channels that cause hyperpolarisation

Question 10

what does the Nernst equation allow us to calculate?

Answer 10

the membrane potential at which K+ will be in equilibrium, given the intracellular and extracellular [K+]

Question 11

which ions are excitatory synapses permeable to and which transmitters are used?

Answer 11

• Na+/Ca2+

- acetylcholine + glutamate

Question 12

which ions are inhibitory synapses permeable to? which transmitters are used?

Answer 12

• K+/Cl-

- glycine, GABA