Lecture 7 - Resting Membrane Potential II

Question 1

What is embedded in the cell membrane that helps neuronal function?

Answer 1

Many diverse proteins such as ion channels

Question 2

At rest, which ion channels open?

Answer 2

Potassium channels

Question 3

Why can’t sodium ions enter the neuronal membrane?

Answer 3

Because it is impermeable to Sodium

Question 4

What is the equilibrium potential for sodium and potassium?

Answer 4

Sodium = -80mV
Potassium = +62

Question 5

What can the Nernst equation not calculate?

Answer 5

The Nernst equation cannot be used to calculate the RMP.

Question 6

Why can’t the Nernst equation not calculate RMP?

Answer 6

The equation assumes that the membrane is equally permeable to both potassium and sodium.

Question 7

What is RMP more permeable for K and Na?

Answer 7

Potassium

Question 8

What causes sodium to leak across the membrane?

Answer 8

a concentration and electrostatic push on sodium

Question 9

How does the sodium leakage change the RMP?

Answer 9

itchanges the RMP to -65mV instead of -80mV

Question 10

How is the Goldman Equation useful?

Answer 10

The Goldman equation is better at predicting the RMP since it takes into account both concentration and permeability for multiple ions.

Question 11

what can dramatically affect membrane potential?

Answer 11

Changing the amount of extracellular potassium

Question 12

What ways concentration gradients are maintained?

Answer 12

Bonds 3+ ions and ATP inside the cell
Changes the confirmation ( shape) of the protein
Releases sodium outside and picks up 2 K+ ions
Binding of potassium to the pump changes it’s conformation and brings the potassium ion the neuron.

Question 13

How do astrocytes buffer extracellular potassium?

Answer 13

• Buffer the amount of ions and chemicals in extracellular space
  
  • Regulate external concentrations of potassium
  • Astrocytes absorb potassium ions through channels in their membrane, this is an effective way to keep potassium low.

Question 14

What is the resting membrane potential?

Answer 14

The RMP is a balance between the equilibrium potentials for both K+ and Na+ that depends highly on the permeability of the membrane to each ion.

Question 15

What is the Resting membrane potential for Potassium?

Answer 15

K+ in = 100 mM
K+ out = 5 mM
EK = –80 mV
Permeability = High (40) Some K+ leaks out

Question 16

What is the resting membrane potential for sodium?

Answer 16

Na+
in = 15 mM
out = 150 mM 
ENa = +62 mV
Permeability = Very Low (1) Some Na+ leaks in