packet 3 Flashcards
Action potentials of all active cells can be detected and recorded
EKG
atrial depolarization
* muscle contraction signal
P wave
conduction time from atrial to ventricular excitation
P to Q interval
ventricular depolarization
*stronger action potential
QRS complex
ventricular repolarization
T wave
At 75 beats/min, one cycle requires 0.8 sec.
End diastolic volume (EDV)
End systolic volume (ESV)
Stroke Volume (SV)
one cardiac cycle
volume in ventricle at end of diastole, about 130ml
end diastolic volume
volume in ventricle at end of systole, about 60ml
end systolic volume
the volume ejected per beat from each ventricle, about 70ml
SV = EDV - ESV
stroke volume
brief period when volume in ventricles does not change– ventricles relax, pressure drops and AV valves open
Isovolumetric relaxation
as blood flows from full atria
diastasis: as blood flows from atria in smaller volume
atrial systole pushes final 20-25 ml blood into ventricle
Ventricular filling
ventricular systole
isovolumetric contraction
ventricular ejection: as SL valves open and blood is ejected
ventricular systole
erratic heartbeat, uncoordinated contractions
fibrillation
interference with AV node erratic, incomplete atrial contractions. Often secondary to other heart problem, and rarely life-threatening.
Treatment: drug/electro-cardioconversion; anti-coagulants
Symptoms: none, palpitations, fainting, nausea, chest pain; can lead to stroke and congestive heart failure.
atrial fibrillation
erratic, incomplete ventricular contractions. Immediately life-threatening due to lack of somatic, pulmonary, and cardiac circulation; often secondary to other heart disease.
Symptoms: sudden collapse; death often first “symptom.”
Treatment: electric cardioconversion, then treat underlying issue
ventricular fibrillation
