Notes on Excitable Membrane, Myelin - Fundamentals of Physiology | BMS 360, Study notes of Biology

Download Notes on Excitable Membrane, Myelin - Fundamentals of Physiology | BMS 360 and more Study notes Biology in PDF only on Docsity! 25 January Excitable membrane has voltage-gated ion channels Stimulus → graded potential Stimulus reaching threshold → action potential Sodium voltage-gated channel Resting conditions – closed Depolarization – opens (if greater than threshold) Na+ flows in, down concentration gradient Shortly afterward – inactivated Cannot open if inactivated Closing pushes out inactivation gate Potassium voltage-gated channel Opens more slowly than Na+ channels Opens after depolarization K+ flows out, down concentration gradient Action potentials are not degenerative, when channels are activated, more channels in the vicinity become activated Signal spreads, travels down the axon Only goes in one direction because the area the signal has just passed is in its refractory period Myelin Saltatory conduction – signal jumps over myelin from node to node