Lecture 3 (Membrane Potential)

Question 1

Potential Energy

Answer 1

• created by charges separated by distance
• measured in volts

Question 2

Membrane Potential (V,m)

Answer 2

• charges are separated by membrane
• Causes
  
  • concentration gradient Na+ and K+
  • leak channels
    
    • K+ tends to leak out
• due to very small imbalance of charge at membrane

Question 3

Ion Flow

Answer 3

• concentration gradient
• electrical gradient

Question 4

Equilibrium Potential

Answer 4

• force due to con gradient = electric grad
• no net movement of that ion
• Calc w/ Nernst Eq
  
  • calc eq pot for 1 ion w/ conc gradient
• K= -90
• Na = 60
• Cl- = -60
• Ca++ = 128

Question 5

Vm = Weighted Average

Answer 5

• Goldman-Hodgkin-Katz
  
  • weighted average of eq potentials
  • weighting factor = permeability

Question 6

Na/K+ ATPase

Answer 6

• establishes Na + and K+ gradient
• few ions need to move

Question 7

Depolarization

Answer 7

• when Vm becomes less negative

Question 8

Hyperpolarization

Answer 8

• when Vm becomes more negative

Question 9

Gated Ion Channels

Answer 9

->change in Vm