COGS 1 Lecture Notes - Lecture 16: Schwann Cell, Membrane Potential, Resting Potential
Document Summary
Each neuron receives an impulse from another neuron and must pass it on. Polarization of the neuron"s membrane: sodium is on the outside, and potassium is on the inside. Polarized - electrical charge on the outside is positively charged while inside is negative. Inside also contains negatively charged proteins and nucleic acids. Resting potential - when neuron is inactive and polarized. Action potential: sodium ions move inside the membrane. When stimulus reaches a neuron all of its gated ion pumps open suddenly. Threshold level - point at which there is no holding back. All or nothing - if sti(cid:373)ulus does(cid:374)"t exceed threshold there is no action potential. Impulse must move between uninsulated gaps called nodes of ranvier that exist between each schwann cell. Repolarization: potassium ions move outside, sodium ions stay inside the membrane. After sodium flooded into the cell, gates open to allow potassium to move out.
