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What are the 2 periods of cardiac cycle?
- Systole (contraction)
- Diastole (relaxation)
What are the 4 phases of cardiac cycle?
- Ventricle filling
- Isovolumetric ventricular contraction
- Ventricle ejection
- Isovolumetric Ventricular Relaxation
What is stroke volume (definition and number)?
- Volume of blood ejected by the ventricle each beat
- 70 mL
What is ejection fraction?
- fraction of end-diastolic vol ejected during a heartbeat
What is cardiac output?
- Vol of blood pumped by each ventricle per min
- Average CO = 5 L/min at rest
What controls the SA node?
What are the primary factors affecting stroke volume?
- Ventricular contractibility
- End-diastolic volume
What factors influence stroke volume?
- Venous return => end-diastolic volume
- Sympathetic Activity/epinephrine => contractibility
- Arterial pressure (afterload)