Physiology 2130 Lecture Notes - Lecture 4: Resting Potential, Axon Hillock, Myelin

• School: Western University
• Department: Physiology
• Course: Physiology 2130
• Professor: Carlie Bell

Document Summary

Learning objectives: explain the difference between excitable and non-excitable cells, excitable cell a cell that is able to use the resting membrane potential to generate an ele(cid:272)tro(cid:272)he(cid:373)i(cid:272)al i(cid:373)pulse (cid:272)alled a(cid:374) (cid:862)a(cid:272)tio(cid:374) pote(cid:374)tial(cid:863, ex. Na+ are the ions responsible for initiating the action potential. The (cid:862)overshoot(cid:863) (cid:894)(cid:272)urve at top(cid:895) is due to na+ gates (cid:272)losi(cid:374)g a(cid:374)d k+ gates beginning to open again. Na+/k+ pump is not required for repolarization. Membrane potential is brought back to resting levels by the continued increased conductance of k+ when. Na+ permeability has returned to normal: refractory periods, absolute refractory period - the period of time when the na+ gates will not open to fire another action potential (1/10 of a millisecond) Interrupts the natural flow of action potentials along the axon to the point where no transmission occurs. Lots of na+ flows into the cell, and a few k+ leave. This triggers a lo(cid:272)al depolarizatio(cid:374) (cid:272)alled a(cid:374) (cid:862)e(cid:374)d plate pote(cid:374)tial(cid:863) (cid:894)epp(cid:895).