electrophys workshop Flashcards
cells in the left & right atria are _____ that produce _____
contractile
fast-response APs
only _____ cells can spontaneously depolarize, bc _____
conducting
bc they express HCN (funny) channel
why do contractile cells NOT spontaneously depolarize, & what does this mean for their membrane potential
no expression of HCN (funny) channel
stable membrane potential
do His/Purkinje cells express HCN (funny) channel, & what does this mean
express a small amount of HCN (funny) channel
= slow rate of spontaneous depolarization
as you go from SA node -> AV node -> His/Purkinje, the rate of depolarization _____, bc _____
decreases
density of HCN (funny) channels decrease
draw table of cardiac cell types
draw table of channels types
what are nodal cells
cells in SA / AV nodes
what type of AP is this
SLOW AP
what type of AP is this
FAST AP
positive chronotropic affect will act on what part of the heart, & what will happen
SA node
increases HR
positive dromotropic affect will act on what part of the heart, & what will happen
AV node
increases conduction velocity
cellular hypoxia cascade of cellular events in the pacemaker cells (= severe bradycardia)
decreased O2
->
decreased Na+/K+ ATPase activity
(& decreased AC activity)
->
decreased intracellular K+
(increased extracellular K+)
->
localized hyperkalemia
->
disruption of transmembrane K+ gradient = membrane depolarization
(in pacemaker cells)
hyperkalemia _____ membrane potential, which causes _____
depolarizes
decreased HR
(in contractile cells)
hyperkalemia initially _____ membrane potential, which causes _____
depolarizes
initial increased conduction velocity
