Resting Membrane Potential Flashcards
Combination of an electrical gradient and chemical gradient is
Electrochemical gradient
Ions subjected to an electrochemical gradient will move!
Explain the membrane potential of a cell
Occurs due to electrical gradient across a cell membrane
Unequal distribution of charges (ions)
Established by ATPase transporters
Measured in mV
The membrane potential of s cell can change due to movement of ions which means it is ____
Not constant
Explain the resting membrane potential
Special case of steady state balance between active transport and leakage of ions
For most cells the resting membrane potential is between what
-20mV and -90mV
Resting membrane potential is at a steady state which means
It is not an equilibrium
Convention is ____
Inside with respect to outside
The membrane potential difference ____ when the membrane potential is depolarizer
Decreases
The membrane potential difference ____ when the membrane potential is hyperpolarized
Increases
The concentration of K is maintained over time because the system is at a steady state because __
The rate of leakage through leakage channels is exactly balanced by active transport
When is a cell not in equilibrium
When it requires constant energy to stay equal
Without a K pump what would eventually happen to the cell
K would eventually leak out until the inside and outside are at equilibrium !
How can we make K stay inside the cell if we shut off the pump
Make inside negatively charged to attract the K ions
Make the inside negative with respect to the outside
The amount of voltage necessary to keep the K inside is called the
Equilibrium potential
Explain the equilibrium potential
The membrane potential that exactly opposes the steady state electrochemical gradient for an ion
The equilibrium potential follows the convention which means
Inside with respect to the outside
How do we calculate the equilibrium potential for any ion at 37degrees C
What is this equation called
Eion = 61/z X log (ion out/ion in)
Nernst equation
K+ equilibrium potential is
-90 mV
Na equilibrium potential is
+60 mV
Ca equilibrium potential is
+122 mV
Cl equilibrium potential is
-81 mV
Describe independence
The equilibrium potential for each ion is independent of the concentration of the other ions
Give an example of independence
The equilibrium potential for K has no effect on the equilibrium potential for Na or Cl
What is Na relative permeability (number of leakage channels)
1
What is K relative permeability
50
What is cl relative permeability
10
What are proteins ect relative permeability (A-)
0
What does the Goldman equation predict
RMP considering
Relative permeability of Na K and Cl
The concentrations inside and outside of the cell
What is the goldmans equation
Pk [K]in + Pna [Na]in + Pcl [Cl]out
What is the RMP of a normal healthy condition
-78 mV
What is the RMP of kidney failure elevated hyperkalemic
-67 mV (depolarization)
What is the RMP of severe diarrhea (low hypokalemic)
-89 mV (hyperpolarization)
What is the RMP of high levels of anti-diuretic hormone hyponatremic
-79 mV
What is the RMP of very high Na permeability
+58 mV
Where does K ions move when ion channels open
OUT
Where is the most K ions
Inside the cell
What direction will Na move when ion channels open
IN
Where is more Na ions
Outside
Where will Ca ions move when ion channels open
In
Where are more Ca ions
Outside
What direction will Cl move when ion channels open
In
Where are more Cl ions
Outside
To understand why ions move the way they do you need to consider what
Equilibrium potential
Membrane potential of the cell
Ion channels allow ions to diffuse across membranes ______
Down their electrochemical gradient
When ion channels open the ions always moves to make ____=_____
Membrane potential
Equilibrium potential
