Mod2-Obj3: Resting membrane potential

Question 1

Resting membrane potential

Answer 1

The voltage (potential energy) across the plasma membrane, due to the separation of oppositely charged ions

Question 2

Resting membrane potential is generated by…

Answer 2

Differences in Na+ and K+ concentration between the ECF and ICF

Question 3

Resting membrane potential is maintained by…

Answer 3

Active transport using the Na+/K+ ATPase pump

Question 4

Generation of resting membrane potential

Answer 4

Na+ and K+ generate the membrane potential

• ECF rich in Na+
• ICF rich in K+

Question 5

Na+ and K+ want to move down concentration gradient

Answer 5

• Leakage channels for Na+ and K+

- More K+ leakage channels

Question 6

More positive ions leaking our

Answer 6

Inside of plasma membrane negatively charged compared to outside

Question 7

Maintenance of resting potential

Answer 7

The Na+/K+ pump counteracts the diffusion Na+ and K+ through the leakage channels

Question 8

Maintenance of resting potential: The Na+/K+ pump

Answer 8

• Pumps 3 Na+ ions out
• Pumps 2 K+ ions in
• Maintains resting potential through exchange of ions

Question 9

Maintenance of resting potential: Active transport

Answer 9

• Against concentration gradient

- Required ATP

Question 10

Resting membrane potential summed

Answer 10

Interior slightly negative compared to outside
-Membrane potential
Unequal charge across the plasma membrane
-Resting potential averages 50mV to 100mV

Question 11

The Na+–K+ Pump: 6 STEPS

Answer 11

1. ) Three cytoplasmic Na+ bind to pump protein
2. ) Na+ binding promotes hydrolysis of ATP. The energy released during this reaction phosphorylates the pump
3. ) Phosphorylation causes the pump to change shape, expelling Na+ to the outside
4. ) Two extracellular K+ bind to pump
5. ) K+ binding triggers release of the phosphate. The dephosphorylated pump resumes its original conformation
6. ) Pump protein binds ATP; releases K+ to the inside, and Na+ sites are ready to bind Na+ again. The cycle repeats