exam 2 class 13 Flashcards
why do myocardial contractile cell has
longer action potential?
due to Ca2+ entry
myocardial autorhythmic cells ability results from their unstable membrane potential, which starts at and?
slowly drifts upward toward threshold
This unstable membrane potential is called?
pacemaker potential
Whenever pacemaker potential depolarizes to threshold, autorhythmic cell
fires?
an action potential
Autorhythmic cells contain channels
that are different from the channels of
other ?
excitable tissues
When the cell membrane potential is -60mV?
I(sub f) channels that are permeable
to both Na+ and K+ open
funny current
I (sub f)
The I(sub f) channels belong to the family
of HCN channels, or?
hyperpolarization-activated cyclic nucleotide-gated channels
When If channels open at negative membrane potentials?
Na+ influx
exceeds K+ efflux
As the membrane potential becomes more positive, I(sub f) channels gradually
close and?
one set of Ca2+ channels
opens
The resulting influx of Ca2+
continues the depolarization, and the
membrane potential moves steadily
toward threshold
When the membrane potential reaches threshold, a different subtype
of ?
Ca2+ voltage-gated channels opens
the time during which cardiac muscle relaxes
Diastole
the time during which the muscle contracts
systole:
blood flows from an area of _________ pressure to one of __________ pressure
higher, lower
