Physiology 3120 Lecture Notes - Lecture 9: Axon Hillock, Depolarization, Membrane Potential

• School: Western University
• Department: Physiology
• Course: Physiology 3120
• Professor: Anita Woods

Document Summary

Presynaptic nerve causes release of neurotransmitter to post synaptic nerve dendrites. Neurotransmitter builds a positive charge at the axon hillock of the post synaptic cell. Positive load of charge = stimulus that will initial depolarization: depolarize the membrane to threshold. The magnitude of the depolarization required to initiate an action potential. The depolarizing forces must overcome the (cid:498)natural stabilizing(cid:499) forces (cid:523)trying to return to -70 mv) At threshold there are depolarizing forces coming from the positive charge that was started by the. But, the cell wants to stay at -70mv to ensure the balance of ions. Depolarizing forces that started the depolarization have to overcome the stabilizing forces trying to maintain rmp. Positive charge flowing into cell at synapse (- Contributing to electronegativity inside of the cell. K+ leaks out of the cell (remember permeability; cell is very permeable to k+) K+ flows down the concentration gradient; takes positive charge out.