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Page 1: Cardiovascular Physiology - San Diego Miramar Collegefaculty.sdmiramar.edu/faculty/sdccd/kpetti/PHYE280/1-CardioPhys.pdf · Cardiovascular Physiology PHYE 280: Exercise Physiology

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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?


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