Membrane at Rest Selectively Permeable Channels Ion Concentration Differences Nernst Relationship Ion Pumps
Mar 28, 2015
Membrane at Rest
Selectively Permeable Channels
Ion Concentration Differences
Nernst Relationship
Ion Pumps
Reflex Loop: Sensory-to-Motor
Water
Phospholipid Bilayer
Membrane is Impermeable
Channels Allow Ions to Pass
Protein Structure
Ion Channel
Potassium Channel
Potassium Channel Pore
Channels
Ion Concentrations and Nernst Potentials
Nernst Relation
E = 61.54 mV log10 [ion] out/ [ion]in
Lets call it 60 mV
Ion Concentrations and Nernst Potentials
Ion Transporters
Goldman Equation
Vm = 60 log10 Pk[Ko] + PNa[Nao]
Pk[Kin] + PNa[Nain]
Astrocytes Buffer Potassium
• What two functions do proteins in the neural membrane perform to establish and maintain the resting membrane potential?
• ON which side of the membrane are sodium ions more abundant?
• When the membrane is at the potassium equilibrium potential, in which direction (in or out) is there a net movement of potassium ions?
• There is much greater concentration of potassium ions inside than outside the membrane. Why, then is the resting potential negative?
• When the brain is deprived of oxygen, the mitochondria within neurons cease producing ATP. What effect would this have on the membrane potential? Why?
Questions
Next Class
• Chapter 4 The Action Potential