L4 Equilibrium Potential

Question 1

Electrical potential energy

Answer 1

Voltage difference across membrane

Question 2

More charges you separate

Answer 2

The higher membrane potential energy

Question 3

What’s the distribution of ions across the plasma membrane?

Answer 3

Slightly pos outside

Slightly neg inside

Question 4

Ion channels

Answer 4

Polypedtide chain that forms water-filled pore

Are selective

Question 5

3 general types of channels

Answer 5

Ungated/leaky channels
Ligand gated channels
Voltage gated channels

Question 6

Ungated/leaky channels drive

Answer 6

Resting membrane potential

Question 7

Ligand/chemical gated channels drive

Answer 7

Graded potentials

Question 8

Voltage gated channels drive

Answer 8

Action potentials

Question 9

Two driving forces for diffusion of ions through open channels

Answer 9

Chemical driving force (conc gradient)

Electrical driving force (separation of charges)

Question 10

Electrochemical gradient

Answer 10

Chemical and electrical driving forces combined

Can act in same or opposite directions

Question 11

How long will the net flux of an ion continue?

Answer 11

Once concentration and electrical gradient are equal and opposite AKA when it’s in electrochemical equilibrium

Question 12

Equilibrium potential

Answer 12

Refers to diffusion potential (electrical force) that exactly balances or opposes the tendency for diffusion down an ions concentration gradient

Question 13

Magnitude of potential is directly proportional to

Answer 13

Magnitude of concentration gradient

Question 14

K+ equilibrium potential

Answer 14

K+ conc greater inside cell
Conc gradient moves K+ outside cell forming electrical gradient across membrane

Outside + , inside -

The electrical gradient then moves K+ back inside cell

No further movement when inward electrical gradient exactly counterbalances the outward conc gradient

-90mV

Question 15

Na+ equilibrium potential

Answer 15

Na+ greater outside than inside

Conc gradient moves Na+ inside, creates electrical gradient that then moves Na+ back into cell

Once equal and opposite no further movement

+65mV

Question 16

Nerst Equation

Answer 16

Gives equilibrium potential for one ion

E ion = (60/z) log ([ion]out /[ion]in)

Z= ionic valence or charge Na=+1, K=+1, Ca=+2, Cl=-1

[ion]out = extracellular conc for ion mM
[ion]in = intracellular conc for ion mM

Question 17

Log 10^x =

Answer 17

X

Question 18

Only ions that move across the membrane contribute to

Answer 18

Equilibrium potential

Question 19

If a membrane is permeable to both ions then there is

Answer 19

No separation of charge

Question 20

You can only get a potential energy of membrane is

Answer 20

Permeable to something and

Impermeable to something else

Question 21

Do organisms want to be at equilibrium?

Answer 21

No

Na+, K+, and Cl- ions are not in equilibrium

Organisms spend much of their energy establishing and maintaining various gradients

Question 22

What’s the Ek+

Answer 22

-90mV

Question 23

What’s the Na+ equilibrium potential ?

Answer 23

+65mV

Question 24

Where is Na+ greater?

Answer 24

ECF 150mM/L

In ICF 15 mM/L

Question 25

Where is K+ greater?

Answer 25

ICF 150mM/L

In ECF 5mM/L

Question 26

Where is Cl- greater?

Answer 26

ECF 110mM/L

In ICF 5mM/L