Heart valves Prevent backward regurgitation Provide low resistance to forward flow
➢ Prevent backward regurgitation ➢ Provide low resistance to forward flow Heart Valves
Section 1 The Heart as a pum I Cardiac cycle The period from the end of one heart contraction to the end of the next
Section 1 The Heart as a Pump ➢ I Cardiac Cycle ➢ The period from the end of one heart contraction to the end of the next
Cardiac Cycle 0.1 02 3 04 0.5 0.6 07 08 Diastole is longer than Atran Diastole systole Ventricle Diastole Systole Diastole proventricular Open Closed The sequence of systole and valve Closed Open Closed diastole Heart sounds y I ⅡII
Cardiac Cycle ➢Diastole is longer than systole ➢The sequence of systole and diastole
Cardiac Cycle: diastole and systole open Semones losed assad onc atcss alves dosed Diastole Systole
Cardiac Cycle: diastole and systole Diastole Systole
2 The phases of the Cardiac Cycle (1)Period of isometric(isovolumetric or isovolumic)contraction Events: ventricular contraction -> ventricular pressure rise atrioventricular valve close> the ventricular pressure increase sharply Period:0.05 sec Importance: enable the ventricular pressure to rise from o to the level of aortic pressure(after-load
2 The Phases of the Cardiac Cycle (1)Period of isometric (isovolumetric or isovolumic) contraction Events: ventricular contraction→ ventricular pressure rise → atrioventricular valve close → the ventricular pressure increase sharply Period: 0.05 sec Importance: enable the ventricular pressure to rise from 0 to the level of aortic pressure (after-load)