Exam 3: Cardiac Cycle

SA node depolarizes and APs spread across the atria (causing P wave)

(Isovolumetric contraction of the ventricles)

-everuthing that happens during ventricular systole (ventricles contracting), BUT semilunar valves still SHUT

atria begin their relaxation pd (atrial diastole)

as the cardiac AP travels from the AV node to AV bundle to bundle branches to Purkinje fibers and over ventricles causing ventricles to depolarize (causing QRS complex)

AV valves close to prevent blood from flowing back into the atria

-R & L AV valves close at the same time and cause the first heart sound

blood is squeezed out of the R ventricle, through pulmonary semilunar valve, into pulmonary artery

-blood squeezed out of L ventricle, through aortic semilunar valve, into the aorta

muscle of ventricls repolarizes (causinf T wave)

-ventricles relax

as ventricles relax, some blood starts to flow backwards into ventricles

-pulmonary and aortic semilunar valves close to prevent blood flow back into ventricles

-semilunar valves close at same time and caus the second heart sound

AV valves are also closed

-ventricles relax, pressure decr and AV valves open