excitable cells Flashcards
ion concentrations: recall the typical values for the concentration of potassium and sodium ions inside and outside a neuron, and explain why potassium exerts a stronger effect on the resting membrane potential than sodium
EC vs IC ion concentrations
Na+, Ca2+, Cl- greater in EC; K+, organic phosphates- greater in IC; pH greater in IC; osmolarity equal
why doesn’t membrane potential rest at K+ or Na+ resting potential
mainly due to K+ but at rest, membrane isn’t uniquely selective to K+ as some permeability to other ions also especially Na+
Goldman-Hodgkin-Katz equation
calculates membrane potential depending on how open channels are: P=0 fully closed; P=1 fully open
movement of ions influencing membrane potential change
movement changes membrane potential toward equilibrium potential for that ion; not due to ion pumps (based on diffusion influx of ions when ion-specific channels opened)
why is resting membrane potential mainly due to K+ not Na+
Pk»>Pna so membrane potential nearer eqm potential for K+ than Na+
