ION MOVEMENT AND ACTION POTENTIAL question n answers rated A+ 2023

ION MOVEMENT AND ACTION POTENTIALMembrane Potential - correct answer separation of positive and negative charges across membrane Resting Membrane Potential RMP - correct answer cell is at rest electrically movement of ions across plasma membrane produces changes in membrane potential - correct answer Rapid, transient fluctuations in membrane potential serve as electrical signals, allowing cells to communicate Depolarization - correct answer decrease in potential, membrane less negative closer to 0, less seperation of charge Repolarization - correct answer return to resting potential after depolarization recovery Hyperpolarization - correct answer increase in potential; membrane more negative than RMP greater seperation of charge Changes in membrane potential - correct answer Brought about by changes in ion movement across membrane Ion channels - correct answer gating of channels; stimulus-dependant Allows cell to gain control over simple diffusion of ions Ion movement redistributes charge causing change in potential Types of Ion channels - correct answer Voltage-gated ligand-gated stretch-activated leak Main criteria for classifying channels is the mechanism of gating Voltage- gated channels - correct answer respond to change in voltage very selective Ligand-gated channels - correct answer norepinephrine, acetylcholine a ligand must bind before the channel can be open Stretch-activated - correct answer these channels are opened to due stretch mechanisms Leak channels - correct answer Na/ K channels always open Always leak Ion current flow - correct answer OHM's Law- describes ionic current flow across the membrane for a particular ion: I= (Vm - Eion)/ R Vm= Membrane potential Eion= Equilibrium potential Higher resistance, lower current OHM's Law Conductance (g) - correct answer 1/ R; proportional to membrane permeability, how many channels are open/ closed Iion = gion (Vm - Eion) Ohm's Law vs Fick's Law - correct answer Ion current Flow across membrane: Iion = gion (Vm - Eion) Diffusion of nonelectrolyte across membrane: J = Ps ([S]o - [S]i) Conductance for an ion (gion) is similar to pereability coeff for a solute Ps Driving force for an ion (Vm - Eion) is similar to delta[S] for solute