Heart Function and Cardiac Cycle (and EKG) Flashcards
what are the major peaks of an EKG
P - atrial depolarization – from SA node to AV node
QRS - ventricle depolarization (and atrial repolarization)
T - ventricular repolarization
what causes a heart block?
occurs when an electrical signal from the atria to the ventricles is disrupted
-P –> QRS
what is a 1st degree heart block and what happens on an EKG?
PR interval is wide – signal is taking a longer time to get to the ventricles
what is a 2nd degree heart block and what happens on an EKG?
sometimes the QRS drops – ventricles are atypical during contraction
what is a 3rd degree heart block and what happens on an EKG?
P and QRS doing their own thing independently – connection in the bundle is blocked
what is end diastolic volume?
how much blood is in the ventricles after filling (preload)
what is end systolic volume?
how much blood is left in the ventricles after contraction
what is stroke volume?
how much blood is pushed out in one beat – difference between end diastolic volume and end systolic volume
what is ejection fraction?
percentage of how much blood the left ventricle pumps out – indicator of heart strength
what are the variables used to determine cardiac output?
heart rate x stroke volume
what effect does change in preload have on blood pressure, cardiac output, or stroke volume?
more preload means a higher BP, which then increased cardiac output and stroke volume
what effect does change in afterload have on blood pressure, cardiac output, or stroke volume?
more afterload means increased blood pressure, decreased cardiac output, and decreased stroke volume
what is afterload?
not a volume, but how much pressure the ventricle has to overcome to push blood out – how much is left in the ventricle after contraction
what effect does heart rate have on blood pressure, cardiac output, and stroke volume?
increased heart rate would increase BP, increased cardiac output
what effect does contractility have on blood pressure, cardiac output, or stroke volume?
increase contractility would increase BP, increase CO, and SV
