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Cardiovascular Physiology
PHYE 280: Exercise Physiology
Kevin Petti, Ph.D.Departments of Natural Sciences,
Health, Exercise Science and NutritionSan Diego Miramar College
Objectives
ω Identify the four components of fitness
ω Identify basic heart anatomy and blood flow
ω Understand the following cardiodynamicvariables: systole, diastole, stroke volume,cardiac output, ejection fraction, the cardiacconducting system, blood pressure, andvenous return
ω Describe how these adapt to exercise
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Components of Fitness
ω Cardiorespiratory Enduranceν Ability of heart, lungs and blood vessels to deliver O2 to
exercising muscles
ω Muscular Strengthν Maximum amount of force a muscle can exert during a
single contraction
ω Flexibilityν Range of Movement (ROM) at a joint
ω Body Compositionν High lean mass or fat-free mass (muscle and bone)ν Low fat mass
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Basic Cardiac Anatomy
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The Coronary Arteries
ω Right
ω Leftν Anterior
Descending
ν Circumflex
Valves of the Heart
ω Atrioventricular Valvesν Tricuspid Valve
λ Between RA and RV
ν Bicuspid/Mitral Valveλ Between LA and LV
ω Semilunar Valvesν Pulmonary Valve
ν Aortic Valve
ω Chordae tendineae andpapillary musclesassociated w/ AV Valves
ω Valves prevent theregurgitation of blood
ω Valves open and close viachanges in chamber BP
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Cardiac Physiology Concepts
ω Conducting System of the Heartω Electrocardiogram (ECG)ω Cardiodynamics
ν EDV, ESV, SV, EJ, Q
ω Cardiac Outputλ At rest vs. exerciseλ Trained vs. untrained
ω Blood Pressure
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Conducting System of the Heart
ω The heart is autorhythmic beats w/o nervous stimulation
ω The cells responsible for initiating and distributingthe stimulus for cardiac contraction are the heart’sconducting system
ω Comprised ofν Sinoartial (SA) Nodeν Atrioventricular (AV) Nodeν Conducting Cells
λ AV Bundleλ Bundle Branches (Bundle of His)λ Purkinje Fibers
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The Electrocardiogram (ECG)
ω Systole - chamber contractionω Diastole - chamber relaxation
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Cardiodynamics
ω End-Diastolic Volume (EDV)ν Volume of blood in each ventricle at the end of
ventricular diastole
ω End-Systolic Volume (ESV)ν Volume of blood in each ventricle at the end of
ventricular systole
ω Stroke Volume (SV)ν Amount of blood ejected from each ventricle per beatν Can be expressed as EDV - ESV = SV
ω Ejection Fractionν Percentage of EDV ejected in ventricular systole
Cardiodynamics
ω Cardiac Outputν Amount of blood ejected from each ventricle in
one minuteν Perhaps the most important variable of cardiac
functionν Can be expressed as below:Q = Hr x SVCardiac Heart StrokeOutput Rate Volume(ml/min) (beats/min) (ml/beat)
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Cardiac Output at Rest
Q = Hr x SVCardiac Heart StrokeOutput Rate Volume(ml/min) (beats/min) (ml/beat)
6000 ml/min = 75 bpm x 80 ml/beator 6 l/min
Cardiac Output at rest equals 6 liters/minuteAverage adult has ≈ 5 liters of blood
Cardiac Output During Exercise
Q = Hr x SVCardiac Heart StrokeOutput Rate Volume(ml/min) (beats/min) (ml/beat)
13,440 ml/min = 120 bpm x 112 ml/beator 13.4 l/min
Cardiac Output can more than double during moderate exercisefor the average adult
Elite athletes can have Cardiac Outputs in excess of 25 l/min!180 bpm x 160 ml/beat = 28.8 l/min
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Cardiac Output Adaptations inResponse to Aerobic Training
ω Resting heart rate decreases as a result of increasedfitness
ω What would this do to SV if Q remains constant?
ω This answer is a result of Starling’s Law that states⇑EDV = ⇑ SV
ω SV ⇑ with training, so what happens to exercisingHR at a particular intensity (10 min. mile) as onebecomes more trained?
Factors Affecting Stroke Volume
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Factors Affecting Cardiac Output
Blood Pressure
ω Systemic arterial pressureν Measured in mm Hg millimeters of mercury
ν Declines further from heart
ω Mean Arterial Pressure (MAP) is most often used instudies reporting a single blood pressureν 1/3 of pulse pressure (systolic-diastolic) + diastolic pressure
ω Regulated closely by neural and hormonalmechanisms; is a function of resistance to blood flow
ω Resistance is a function of vessel diameter, vessellength, blood viscosity, blood turbulence
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Measuring Blood Pressuresystolic/diastolic
Blood Pressure
ω Resting BP≈120/80 mmHg
ω MAP =
93.3mm Hg
ω Exercising MAPcan exceed113 mmHg(200/70)
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Blood Pressureand Venous Return
ω BP at start of venous system is 1/10 of that at startof arterial system
ω BP at right atrium is only 2 mm Hg!
ω Venous return is assisted by muscular compression,and the respiratory pump
ω Both of these are extremely important duringexerciseν Why is it important to cool down after aerobic exercise?