Xa izihlunu zentliziyo zifingana (okanye singathi xa intliziyo izicutha ibencinane izicuthela ngaphakathi) ibizwa ngokuba yisystole. Xa ke ngoku esi sihlunu siziyekelela (singazizicuthi), kuthiwa ke ngoku le yidiastole. Lo msebenzi we-systole wenziwa zii-atria zombini ngokubambisana. Kodwa yona i-atria yenza i-systole phambi kokuba zenze ii-ventricles. Nangona i-atrial systole isiza kuqala kune-ventricular systole, ziyenza zone ngaxeshanye kunjalo nje zibambisene i-diastole. Le knqubo ke kuthiwa yi-cardiac diastole