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 = mV log 10 [ion] out / [ion] in Lets call it 60 mV

Ion Concentrations and Nernst Potentials

Ion Transporters

Goldman Equation V m = 60 log 10 P k [K o ] + P Na [Na o ] P k [K in ] + P Na [Na in ]

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