The P-wave of the ECG represents what cardiac event? atrial depolarization What event is responsible for making first heart sound? Closure of the AV valves During ventricular systole, which event occurs first? AV valve closes The wave of systolic pressure which starts at the heart and spreads throughout the arterial network is called: Pulse The pace-maker of heart that initiates impulses in the atria is: SA Node What are the two main factors that affect cardiac output? -heart rate -pulse -stroke volume -both a. and c. are correct A heart murmur refers to what condition? abnormal blood flow Choose the correct electrical conduction pathway for depolarization of the heart: SA node, atria, AV node, bundle of His, Purkinjee fibers, ventricles Mitral valve insufficiency in dogs may lead to: left side CHF What is the effect of parasympathetic stimulation on heart? decreases the heart rate and coronary blood flow The difficult breathing is termed as: Dyspnea During inspirat