Factors that effect EDV and ESV The Heart as a Pump Cardiac Output Cardiac Reserve Factors that effect EDV and ESV Be able to use the concepts of EDV, ESV and SV to determine CO. Be able to explain the concept of cardiac reserve. Be able to define vagal tone, bradycardia and tachycardia. Be able to discuss how preload, contractility and afterload affect EDV. ESV and SV. Marieb 18

The Heart as a Pump Stroke Volume Cardiac Output Cardiac Reserve

The Two Circulations Volumes in R/L ventricles are equal Volumes in the two circulations are NOT

Stroke Volume End Diastolic Volume (EDV) End Systolic Volume (ESV)

Cardiac Output (CO) CO= HR x SV

Cardiac Reserve COMax - CORest = COReserve

Cardiac Reserve COMax - CORest = COReserve

Improving Cardiac Reserve SVMax HRRest

Resting Heart Rate Decreases from Birth 140-160 ♂ 64-72 ♀ 72-80

Tachycardia (100 or more beats/min) Bradycardia (60 or less beats/min) Miguel Indurain A Bradycardia Sufferer

Heart Rate Control Parasympathetic (Vagal Tone) Sympathetic Adrenal

Changing Stroke Volume Increasing/Decreasing EDV Increasing/Decreasing ESV

Factors that Alter EDV and ESV Preload Contractility Afterload

Preload: Heart “Stretchiness” Affects EDV Cardiac muscle stretches as heart fills

Frank-Starling Law of the Heart The volume of blood ejected from a ventricle during systole (contraction) depends on the volume present in the ventricle at the end of diastole (relaxation)

Frank-Starling Curve

Venous Return and Preload Blood returning to heart from veins Slow heart rate Exercise Very fast heart rate Blood Loss

Contractility increases SV Contractile strength at a given muscle length More Ca++ Less Ca++

Afterload Decreases Stroke Volume Pressure in aorta decreases the amount of blood that can leave the left ventricle 120mmHg 80mmHg 120mmHg 100mmHg