netter61

Cardiac Cycle

CARDIOVASCULAR PHYSIOLOGY

Figurę 4.9 Cardiac Cycle

The cardiac cycle represents one complete scquenct: of atnal and verv tricular contraction and rcłaxation. Depicted here are the key elcctrical and hemodynarnic events associatod wilh a single tycie. Changes in leń airial, ventricular, and aortic pressure; aortic Wood flow; venłrkiilar yolurne; heart sounds; jugular venous pressure; and the CCC are shown. The S heart sound resułts from the dosing of the mitral and tri-cuspid valv«, whereas the S, heart sound results from the dosing of the aortic and pulmonic valves. Both S. and are sounds associatod wilh filling of the ventrides. They are normally diffit.ult to hear in healthy adults. is heard in healthy ditldren and in States of high car-diac output. $., is associated with ventricular filling during atrial contraction. Ihe coniponents of the jugular venous pulse are the a wave. caused by right atnal contraction; the c wave, which results from bulging of the Iric uspid valve into right atrium during right ventricular contraction; and the v wave_r resulting from inereased right atrial vol-urne (and pressure) as venous blond fills ihts chamber before the opening of the Iricuspid valve. Ihe coniponents of tlw* FCG are described in Frgures 4.8 to 4.8.

74