Autorhythmicity Flashcards
what are the major phases of SA node AP
prepotential
depolarization
repolarization
what happens during the prepotential phase of SA node AP generation?
a small number of Na+ channels open
v-gated K+ channels that opened in repolarization phases are closing
v-gated Ca++ channels are beginning to open
in which phase of SA node AP generation do v-gated Ca++ channels begin to open?
prepotential
in which phase of SA node AP generation do a small number of NA+ channels open?
prepotential
what happens during the depolarization phase of SA node AP generation?
v-gated Ca++ channels are open
v-gated K+ channels are closed
during which phase of SA node AP generation are all v-gated Ca++ channels open and v-gated K+ channels are closed?
depolarization
what happens during the repolarization phase of AP generation in the SA node?
v-gated Ca++ channels close
v-gated K+ channels open
in which phased of AP generation of the SA node are all v-gated K+ channels open and Ca++ channels closed?
repolarization phase
how long does the AP generation cycle of the SA node take?
about 300 ms
during SA node AP generation, when do Ca++channels begin to open?
prepotential, all open in depolarization
during SA node AP generation, when do Ca++ channels close?
repolarization
during SA node AP generation when do K+ channels open?
repolarization
during SA node AP generation when do K+ channels close?
begin to close during prepotential, totally closed during depolarization
when do Na++ channels open in SA node AP generation?
prepotential
what is the absolute refractory period for cardiac muscle cells?
a period of time when cardiac muscle cells are completely insensitive to any further stimulation
what is the relative refractory period for cardiac muscle cells?
a period of time when cardiac muscle cells exhibit reduced sensitivity to additional stimulation
what is the fn of the long refractory period of cardiac muscle cells
prevents tetanic cntx
what is an ECG?
an electrocardiogram
records the electrical events in the myocardium
what does a HCP do when they interpret an ECG?
correlate the recorded electreical events with the mechanical events of the cardiac cycle
what is the P wave of an ECG?
depolarization of atrial myocardium
what does the P wave of an ECG correlate to?
onset of atrial cntx
what is the QRS complex of an ECG?
depolarization of the ventricle
simultaneous repolarization of the atria
what does the QRS complex of an ECG correlate to?
onset of ventricular cntx
what is the T wave of an ECG?
repolarization of ventricles
