So this diagram describes the relative concentrations of sodium ions and potassium ions on the outside and inside of the neuron cell membrane. So this is the phospholipid bilayer, the membrane of the neuron, let's say, found on the exxon hillock where the action potential is generated. But, of course, no action potential is being generated in this particular case. So this is the outside portion of the cell. It's the extracellular portion of the membrane. This is the inside portion of the cell, the cytoplasmic side of our membrane.