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Cardiovascular Physiology - San Diego Miramar · PDF fileCardiovascular Physiology PHYE 280: Exercise Physiology Kevin Petti, Ph.D. Departments of Natural Sciences, Health, Exercise

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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

    Identify the four components of fitness

    Identify basic heart anatomy and blood flow

    Understand the following cardiodynamicvariables: systole, diastole, stroke volume,cardiac output, ejection fraction, the cardiacconducting system, blood pressure, andvenous return

    Describe how these adapt to exercise

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    Components of Fitness

    Cardiorespiratory Endurance Ability of heart, lungs and blood vessels to deliver O2 to

    exercising muscles

    Muscular Strength Maximum amount of force a muscle can exert during a

    single contraction

    Flexibility Range of Movement (ROM) at a joint

    Body Composition High lean mass or fat-free mass (muscle and bone) Low fat mass

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    Basic Cardiac Anatomy

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    The Coronary Arteries

    Right

    Left Anterior

    Descending

    Circumflex

    Valves of the Heart

    Atrioventricular Valves Tricuspid Valve

    Between RA and RV

    Bicuspid/Mitral Valve Between LA and LV

    Semilunar Valves Pulmonary Valve

    Aortic Valve

    Chordae tendineae andpapillary musclesassociated w/ AV Valves

    Valves prevent theregurgitation of blood

    Valves open and close viachanges in chamber BP

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    Cardiac Physiology Concepts

    Conducting System of the Heart Electrocardiogram (ECG) Cardiodynamics

    EDV, ESV, SV, EJ, Q

    Cardiac Output At rest vs. exercise Trained vs. untrained

    Blood Pressure

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    Conducting System of the Heart

    The heart is autorhythmic beats w/o nervous stimulation The cells responsible for initiating and distributing

    the stimulus for cardiac contraction are the heartsconducting system

    Comprised of Sinoartial (SA) Node Atrioventricular (AV) Node Conducting Cells

    AV Bundle Bundle Branches (Bundle of His) Purkinje Fibers

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    The Electrocardiogram (ECG)

    Systole - chamber contraction Diastole - chamber relaxation

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    Cardiodynamics

    End-Diastolic Volume (EDV) Volume of blood in each ventricle at the end of

    ventricular diastole

    End-Systolic Volume (ESV) Volume of blood in each ventricle at the end of

    ventricular systole

    Stroke Volume (SV) Amount of blood ejected from each ventricle per beat Can be expressed as EDV - ESV = SV

    Ejection Fraction Percentage of EDV ejected in ventricular systole

    Cardiodynamics

    Cardiac Output Amount of blood ejected from each ventricle in

    one minute Perhaps the most important variable of cardiac

    function 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

    Resting heart rate decreases as a result of increasedfitness

    What would this do to SV if Q remains constant?

    This answer is a result of Starlings Law that statesEDV = SV

    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

    Systemic arterial pressure Measured in mm Hg millimeters of mercury Declines further from heart

    Mean Arterial Pressure (MAP) is most often used instudies reporting a single blood pressure 1/3 of pulse pressure (systolic-diastolic) + diastolic pressure

    Regulated closely by neural and hormonalmechanisms; is a function of resistance to blood flow

    Resistance is a function of vessel diameter, vessellength, blood viscosity, blood turbulence

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    Measuring Blood Pressuresystolic/diastolic

    Blood Pressure

    Resting BP120/80 mmHg

    MAP =

    93.3mm Hg

    Exercising MAPcan exceed113 mmHg(200/70)

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    Blood Pressureand Venous Return

    BP at start of venous system is 1/10 of that at startof arterial system

    BP at right atrium is only 2 mm Hg!

    Venous return is assisted by muscular compression,and the respiratory pump

    Both of these are extremely important duringexercise Why is it important to cool down after aerobic exercise?

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