COGNITIVE SCIENCE 17 The Electric Brain Part 2 Jaime A. Pineda, Ph.D.
Phases of the Action Potential Firing threshold is the point at which the number of activated Na+ channels > inactivated Na+ channels Absolute refractory period Relative refractory period
Nodes of Ranvier Initial segment
Advantages of myelination Reduces number of ion channels Reduces number of Na+ / K+ pump Increases speed of conduction Reduces energy needs
Saltatory Conduction
Exocytosis
RECEPTORS Ionotropic Metabotropic
Ionotropic Metabotropic Form a channel
Ionotropic Receptor agonist
antagonist
Metabotropic Receptor
(leads to opening of channel)
Upregulation Downregulation Changes to Postsynaptic Receptor Density as a Function of the Amount of Neurotransmitter Released