# Shared Flashcard Set

## Details

"Ionic Basis of Rest Mem Pot"
9/12/07--for quiz 1
5
Physiology
Not Applicable
09/12/2007

## Additional Physiology Flashcards

Term
 What is "equilibrium potential"?
Definition
 --Diffusion potential that exactly opposes the tendency for diffusion down conc. gradient. --Ex: Cation diffuses-->increases positive charge on other side of membrane-->stop further diffusion of cation.
Term
 What is the Nerst equation? What is its basic concept?
Definition
 --Used to calculate the equilibrium potential for an ion at a given concentration difference across a membrane. --Calculated 1 ion at a time! E=-2.3 RT/Zf x Log (Ci)/(Ce) E= equilibrium potential 2.3RT/F= constant (60 mV)z= charge on the ion (+1, +2, -1..)Ci= intracellular concentrationCe= extracellular concentration
Term
 What are approximate Nerst potentials for: Na+, K+, Cl-, and Ca2+?
Definition
 ENa+= +65 mVEK+= -85 mVECl-= -90 mVECa2+= +120mV
Term
 What is cord conductance equation?
Definition
 --Evaluates contribution that EACH ion makes to membrane potential. --Weights equilibrium potential (calculated by Nerst) for each ion by its conductance. --Ions w/ HIGH conductance=drive membrane TOWARD equilibrium potential--Ions w/LOW conductance=have little effect on membrane.
Term
 What is Goldman-Hodgkin-Katz equation?
Definition
 --Considers contribution of EACH ion to membrane potential by its relative permeability, rather than conductance (chord conductance)Em=((gK+/gT)x (EK+))+((gNA+gT) x (ENa+))+ ((gCl-/gT) x (ECl-)) + ((gCa2+/gT) x (ECa2+))Em= membrane potentialgK+...= K+ conductance; etc. gT= total conductanceEk+...=equilibrium potential
Supporting users have an ad free experience!