Lab 45: Cardiac Cycle Flashcards
the period during which a heart chamber is contracting is called______
Systole
the period during which a heart chamber is relaxing is called ______
Diastole
during ventricular contraction, the AV valves are ______
Closed
during ventricular relaxation, the AV valves are _______
Open
the pulmonary and aortic valves open when the pressure in the _______ exceeds the pressure in the pulmonary trunk and aorta
Ventricles
the first sound of a cardiac cycle occurs when the ______ are closing.
Av Valves
second sound of a cardiac cycle occurs when the ______ are closing.
Semilunar
the sound created when blood leaks back through an incompletely closed valve is called a _______
Murmur
normally, the _____ node serves as the pacemaker of the heart.
SA
the ________ node is located in the inferior portion of theinteratrial septum
AV
the fibers that carry cardiac impulses front he inter ventricular septum into the myocardium are called _______
Purkinje fibers
a _____ is a recording or electrical changes occurring in the myocardium during a cardiac cycle.
ECG
the P wave corresponds to depolarization of the muscle fibers of the _____
ATRIA
the QRS complex corresponds to depolarization of the muscle fibers of the _______
ventricles
the T wave corresponds to repolarization of the muscle fibers of the ________
Ventricles
Why is the atrial depolarization not observed in the ECG?
There is no distinctly visible wave representing atrial depolarization in the ECG because it occurs during ventricular depolarization. Because the wave of atrial depolarization is relatively small in amplitude, it is masked by the QRS complex
How much time passed from the beginning of the P wave to the beginning of the QRS complexed (P - R interval) in the ECG from lead I?
.14 to .20 seconds
