©GRACEAMELIA 2024/2025 ACADEMIC YEAR. ALL RIGHTS RESERVED
FIRST PUBLISH OCTOBER 2024
NUR968: Membrane Potentials & Action
Potentials; Cell Signaling & Second
Messenger Systems Practice Questions
and Answers
What is the membrane potential? - Ans:✔✔-Defined as the electrical potential difference across a cell's
plasma
How are ions classified? (2) - Ans:✔✔-1. Cations (positively charged)
2. Anions (negatively charged)
Although all positive & negative charges establish membrane potential, what are the 2 key players
(ions)? - Ans:✔✔-1. Sodium
2. Potassium
True or false: The net flux of ions is a continuous dynamic process (never static) - Ans:✔✔-True
How much more permeable is the plasma membrane to potassium? - Ans:✔✔-100x more permeable
Page 1/28
, ©GRACEAMELIA 2024/2025 ACADEMIC YEAR. ALL RIGHTS RESERVED
FIRST PUBLISH OCTOBER 2024
True or false: The Sodium Potassium ATPase Pump moves ions AGAINST their concentration gradient -
Ans:✔✔-True
The plasma membrane contains protein channels called "leak channels." What do these do? - Ans:✔✔-
They leak ions (they are always open)
Which ions are leaked is dependent on what 3 factors? - Ans:✔✔-1. The polarity of the electrical charge
of the ion & the charge on either side of a membrane
2. The permeability or "selectability" (specificity) of the leak channels to an ion
3. Concentration gradient on either side of the leak channel
With potassium & sodium, which ion has the greatest concentration INSIDE the cell? What about
OUTSIDE the cell? - Ans:✔✔-Inside = Potassium
Outside = Sodium
So, why is potassium (a cation) more likely to leak out of the cell? - Ans:✔✔-Because of the permeability
to potassium
Page 2/28
, ©GRACEAMELIA 2024/2025 ACADEMIC YEAR. ALL RIGHTS RESERVED
FIRST PUBLISH OCTOBER 2024
-As potassium leaves, it takes with it a positive charge leaving the inside of the cell "more negative". This
negativity then pulls potassium back in
Recall from Module 1:
When the Sodium Potassium Pump runs, 3 Na+ move OUT; 2 K+ move IN. What is happening
inside/outside of the cell each time this happens? - Ans:✔✔-The inside of the cell becomes more
NEGATIVE & the outside becomes more POSITIVE (Separation of Charges)
What is a key player in maintaining the concentration gradients?*** - Ans:✔✔-Sodium Potassium Pump
-Overall, sodium is predominately on the outside of the cell
-Potassium is predominately kept on the inside
Nernst Equation
-Nobel prize in 1920
-Relates the __ __ to the electrical force
Page 3/28
FIRST PUBLISH OCTOBER 2024
NUR968: Membrane Potentials & Action
Potentials; Cell Signaling & Second
Messenger Systems Practice Questions
and Answers
What is the membrane potential? - Ans:✔✔-Defined as the electrical potential difference across a cell's
plasma
How are ions classified? (2) - Ans:✔✔-1. Cations (positively charged)
2. Anions (negatively charged)
Although all positive & negative charges establish membrane potential, what are the 2 key players
(ions)? - Ans:✔✔-1. Sodium
2. Potassium
True or false: The net flux of ions is a continuous dynamic process (never static) - Ans:✔✔-True
How much more permeable is the plasma membrane to potassium? - Ans:✔✔-100x more permeable
Page 1/28
, ©GRACEAMELIA 2024/2025 ACADEMIC YEAR. ALL RIGHTS RESERVED
FIRST PUBLISH OCTOBER 2024
True or false: The Sodium Potassium ATPase Pump moves ions AGAINST their concentration gradient -
Ans:✔✔-True
The plasma membrane contains protein channels called "leak channels." What do these do? - Ans:✔✔-
They leak ions (they are always open)
Which ions are leaked is dependent on what 3 factors? - Ans:✔✔-1. The polarity of the electrical charge
of the ion & the charge on either side of a membrane
2. The permeability or "selectability" (specificity) of the leak channels to an ion
3. Concentration gradient on either side of the leak channel
With potassium & sodium, which ion has the greatest concentration INSIDE the cell? What about
OUTSIDE the cell? - Ans:✔✔-Inside = Potassium
Outside = Sodium
So, why is potassium (a cation) more likely to leak out of the cell? - Ans:✔✔-Because of the permeability
to potassium
Page 2/28
, ©GRACEAMELIA 2024/2025 ACADEMIC YEAR. ALL RIGHTS RESERVED
FIRST PUBLISH OCTOBER 2024
-As potassium leaves, it takes with it a positive charge leaving the inside of the cell "more negative". This
negativity then pulls potassium back in
Recall from Module 1:
When the Sodium Potassium Pump runs, 3 Na+ move OUT; 2 K+ move IN. What is happening
inside/outside of the cell each time this happens? - Ans:✔✔-The inside of the cell becomes more
NEGATIVE & the outside becomes more POSITIVE (Separation of Charges)
What is a key player in maintaining the concentration gradients?*** - Ans:✔✔-Sodium Potassium Pump
-Overall, sodium is predominately on the outside of the cell
-Potassium is predominately kept on the inside
Nernst Equation
-Nobel prize in 1920
-Relates the __ __ to the electrical force
Page 3/28
