Chapter 18 Heart Lecture 3 Part 1: Cardiac Output

1. Marieb’s Human Anatomy and Physiology Marieb w Hoehn Chapter 18 Heart Lecture 3 Part 1: Cardiac Output

2. Review of Events of the Cardiac Cycle Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2004 • Atrial contraction begins • Atria eject blood into ventricles • Atrial systole ends; AV valves close (S1) • Isovolumetric ventricular contraction • Ventricular ejection occurs • Semilunar valves close (S2) • Isovolumetric relaxation occurs • AV valves open; passive atrial filling S2 S1

3. Cardiodynamics – Important terms • End-diastolic volume (EDV) – amount of blood present in the ventricles at end of ventricular diastole (~ 120 ml) • End-systolic volume (ESV) – amount of blood left in ventricles at end of ventricular systole (~ 50 ml) • Stroke volume (SV) – amount of blood pumped out of each ventricle during a single beat (SV =EDV – ESV) (~ 70 ml) • Ejection fraction – Percentage of EDV represented by the SV (SV/EDV) (~ 55%)

4. Exploring Cardiac Math Formulas

5. Cardiac Output (CO) • The volume of blood pumped by each ventricle in one minute CO = heart rate (HR) x stroke volume (SV) ml/min beats/min ml/beat Example: CO = 72 bpm x 75ml/beat  5,500 ml/min Normal CO  5-6 liters (5,000-6,000 ml) per minute