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