Modulating Membrane Potential

Question 1

Nernst defines equilibrium conditions for?

Answer 1

Single ion species

Question 2

GHK stands for?

Answer 2

Goldman-Hodgkin-Katz

Question 3

GHK equation is also known as?

Answer 3

Constant-Field equation

Question 4

What does GHK equation define?

Answer 4

Instantaneous conditions for multiple ion species

Question 5

Px represents?

Answer 5

Permeability of ion ‘x’ relative to benchmark ion

Question 6

Extracellular concentration of cations is on top/bottom of GHK equation?

Answer 6

Top

Question 7

Extracellular concentration of anions is on top/bottom of GHK equation?

Answer 7

Bottom

Question 8

Vmem represents?

Answer 8

Membrane potential

Question 9

If Vmem is more positive than Nernst potential for cation, what will the net flux be?

Answer 9

Cytosol → ECF

Cation will leave cell

Question 10

If Vmem is more negative than Nernst potential for cation, what will the net flux be?

Answer 10

ECF → cytosol

Cation will enter cell

Question 11

If Vmem is more positive than Nernst potential for anion, what will the net flux be?

Answer 11

ECF → cytosol

Anion will enter cell

Question 12

If Vmem is more negative than Nernst potential for anion, what will then net flux be?

Answer 12

Cytosol → ECF

Anion will leave cell

Question 13

Membrane potential will be closest to Nernst potential for what ion?

Answer 13

Ion with dominant conductance (highest P)

Question 14

For most cells at rest, what is the relationship between Pk and PNa?

Answer 14

Pk&raquo_space; PNa

Question 15

Nerve and muscle are said to be “electrically excitable”. What does that men?

Answer 15

1. Membrane conductance changes in response to imposed electrical gradients
2. Membrane proteins can alter membrane potential

Question 16

Increase Pcat will initiate?

Answer 16

Action potential

Question 17

Increasing PNa will provide?

Answer 17

Upstroke of action potential

Question 18

Increasing PK provides?

Answer 18

Downstroke of action potential (repolarization)

Question 19

Changes in PCl has has what effect on action potential?

Answer 19

Modifies

Question 20

Local anesthetics modify P_?

Answer 20

PNa

Question 21

General anesthetics modify P_?

Answer 21

PCl

Question 22

Addison’s will alter?

Answer 22

[K0]
[Na0]
[Cl0]

Question 23

What accounts for the excitability of tissues?

Answer 23

Physiological alterations in membrane ion permeabilities