BIO 3421 Final- Chapter 4 Neuronal Physiology Review Questions and Complete Solutions

Excitable Cells Capable of undergoing transient, rapid changes in their membrane potentials (action potentials) Nerve cells (neurons) receive, process, initiate and transmit messages Muscle cells contract Polarization Charges are separated across the plasma membrane Depolarization Vm becomes less negative. Repolarized Vm returns to resting potential after depolarization Hyperpolarized Vm is more negative than the resting potential Changes in Vm result from ion movement through ion channels in the plasma membrane Leak Channels: open all the time Gated Channels:open or close in response to specific triggering events: 1. Voltage 2. Chemical, or ligands 3. Mechanical stimulation 4. Thermal stimulation Voltage Gated Channels Respond to changes in Vm Crucial to action potentials Chemically Gated Channels Respond to binding chemical messenger ligand-gated ion channels signal transduction synapses Mechanically Gated Channels Respond to stretching or mechanical deformation touch hearing sensory transduction Thermally Gated Channels respond to local changes in temperature sensory transduction