Membrane Electrophysiology: RMP

Question 1

membrane potential

Answer 1

separation of charge across plasma membrane

potential to do work

in millivolts

Question 2

resting membrane potential

Answer 2

when not sending electrical signals (equilibrium)
-no net ion flow

expressed as intracellular potential relative to extracellular potential

Question 3

intracellular anions

Answer 3

fixed, so cations balance the charge

impermeable molecules (proteins)

Question 4

Na+ K+ Pump

Answer 4

electrogenic
ATP dependent ion pump
indirect contribution to RMP maintaining ion [gradient]

Question 5

what ions have great contribution to RMP?

Answer 5

those with greatest permeability

Question 6

Exchange rate for Na/K pump

Answer 6

3 Na out and 2 K in

positive outside
more sodium outside/potassium inside

Question 7

distribution of Na?

Answer 7

greater in ECF

Question 8

distribution of K?

Answer 8

greater in ICF

Question 9

electrogenic

Answer 9

sodium/potassium pump that causes a net movement of +1 outside of cell

Question 10

diffusion potential

Answer 10

due to concentration difference of an ion

-contributes to RMP

Question 11

distribution of calcium

Answer 11

much more outside cell ECF

Question 12

distribution of chloride

Answer 12

more outside ECF

-larger concentration difference in skeletal muscles

Question 13

force acting on an ion?

Answer 13

1. concentration (chemical) force
2. electrical force

NET force is sum of two

Question 14

electrical force

Answer 14

depends on membrane potentital and charge on particle

Question 15

equilibrium potential

Answer 15

unique for each ion

-when chemical and electrical gradients balance out

Question 16

nernst equation

Answer 16

to predict equilibrium potential for any concentration gradient of an ion

Ex=60/z log10 (Xo/Xi)

Question 17

log10 (10) = ?

Answer 17

1

Question 18

log10 (0.1) = ?

Answer 18

-1

Question 19

net force on ion?

Answer 19

difference between Ex and Vm

Question 20

potassium equilibrium potential?

Answer 20

-90mV

Question 21

sodium equilibrium potential?

Answer 21

+60mV

Question 22

driving force

Answer 22

Vm - Ex

Question 23

if Vm is more negative?

Answer 23

inward current of cations

Question 24

if Vm is more positive?

Answer 24

outward current of cations

Question 25

which ion has greatest driving force?

Answer 25

calcium

Question 26

at RMP what ways would major ions move?

Answer 26

potassium out sodium in calcium in chloride in

Question 27

what determines membrane conductance?

Answer 27

number of open channels | -channels are opening, conductance is increasing

Question 28

rate of ion movement depends on?

Answer 28

external and internal concentrations of ions transmembrane voltage permeability of ion

Question 29

ungated ion channels

Answer 29

leak channels | always open

Question 30

voltage gated channels

Answer 30

open/close in response to membrane voltage change

Question 31

ligand gated channels

Answer 31

open/close in response to binding ligand

Question 32

potassium contribution to RMP?

Answer 32

high K+ inside cell 2 opposing forces - chemical vs electrical K+ not at EQ ungated, leak channels always open NET EFFLUX OF K+

Question 33

increased K+ conductance?

Answer 33

hyperpolarization

Question 34

decreased ECF potassium?

Answer 34

hyperpolarization

Question 35

increased ECF potassium?

Answer 35

depolarization

Question 36

RMP and K?

Answer 36

very sensitive in change to ECF concentration of potassium

Question 37

reversal potential

Answer 37

voltage at which current direction is reversed nernst potential of ion

Question 38

major determinant of RMP?

Answer 38

potassium

Question 39

diffusion of K+

Answer 39

concentration - OUT | electrical - INSIDE

Question 40

RMP and Na?

Answer 40

high sodium outside cell low permeability to Na+ large force on sodium (far from EQ)

Question 41

is resting membrane potential sensitive to changes in sodium?

Answer 41

NO

Question 42

increase or decrease in ECF sodium?

Answer 42

minimal effect on RMP

Question 43

sodium concentration gradient

Answer 43

INSIDE cell

Question 44

sodium electrical gradient

Answer 44

INSIDE cell

Question 45

skeletal muscle, cardiac, and nerve cell RMPs?

Answer 45

-60 to -90mV

Question 46

Na/K pump

Answer 46

continues to restore gradient by pumping K+ back in