BERNSTEIN PHSC 2301 Membrane Potential

cells have a voltage or electrical charge across the plasma membrane which is called what; electrical potential difference

membrane potential

what is the membrane potential of a cell

-60 to -90 mv

opposite charges in the membrane potential accumulate in a thin or thick layer

thin

accumulated charges are only a small fraction of the total number of ions (true or false)

true

"Inside" has a _____________ charge relative to the "outside"

negative

what is on the outside of the membrane

extracellular fluid

ECF is considered to be how many millivolts?

zero (electrical "ground")

squad giant axons is a convenient model since 1930th and has a diameter of what

0.5-1mm

what are the ions responsible for the membrane potential?

sodium and potassium

chloride and protein are ions responsible for membrane potential (true or false)

false

proteins are found on the membrane potential because they are small and light (true or false)

false (thought at first but not always negative, proteins are also big and heavy)

what is the concentration of sodium ions outside the cell and inside the cell

145, 10

what is the concentration of potassium ions outside the cell and inside the cell

5, 140

sodium _________ the cell through non-gated channels

enters

potassium ______ the cell through non-gated channels

leaves

sodium and potassium use gated channels to transport in and out of the cell (true or false)

false (they use non-gated channels)

higher concentration of potassium ions are found (inside/outside) the cell and higher concentration of sodium ions are found (inside/outside) the cell

inside, outside

unequal ion transport, when one molecule of sodium goes into the cell, _______ molecules of potassium leaves the cell

100

unequal ion transport makes up how much of the membrane potential

80%

the sodium-potassium pump (electrogenic pump) makes up how much of the membrane potential

20%

sodum -potassium pump (electrogenic pump)

3Na+ pumped out for every _______ pumped into the cell

2K+

across the membrane operation of two driving forces results from electrical potential across the membrane and concentration (chemical) gradient across the membrane (true or false)

true

when the electrical forces balance the driving force of the concentration gradient, then ____________________________ is reached

electrochemical equilibrium

electrical field _____________ further ion movement

opposes

equation that describes the relationship between the concentrations of an ion on either side of the cell membrane and potential (E)

Nernst equation

the concentration gradient for potassium tends to move in the cell (true or false)

false (out of the cell)

as potassium leaves the cell, the outside becomes more positive (true or false)

true

the membrane is impermeable to the large intracellular protein anion and the inside of the cell becomes more negative as K+ ions move out, leaving behind A- which creates an electrical gradient to move K+ into the cell (true or false)

true

net movement stops and equilibrium is reached when electrochemical potential is at what

0

each of the individual ions has an equilibrium potential called what

E ion

Nernst equation relates the value of the electrical chemical potential difference and the specific ion at equilibrium, when the membrane is permeable only to that ion (true or false)

true

EK = -89.1 which is closest to the range -60 - -90 which means that potassium is more responsible for creating the negative charge inside the cell (true or false)

true

ENa is 71.5 which means that the movements of Na and K have essentially _____________ effects on membrane potential

opposite

nernst equation connects what?

electrical and chemical energy

by using __________________, it is possible to predict potential for the most common ions

nernst equation

in most cells, the resting membrane potential is close to equilibrium potential for potassium and dominated by potassium (true or false)

true

cells can change membrane potential by modifying what

relative ion permeability

resting membrane potential can be measured directly and calculated by taking into account all the permeable ion fluxes through the non-gated channels. resting membrane potential is achieved when all the ionic fluxes balances each other (true or false)

true

a cell can regulate its membrane potential by controlling relative permeability of the cell membrane to what?

ions

electrical forces across the membrane are small or large

large

membrane potential is what?

membrane thickness is what/

thus it is equivalent to what

80mv, 10nm, 80,000 V/cm