Download Cardiovascular Physiology - San Diego Miramar College

Cardiovascular Physiology
PHYE 280: Exercise Physiology
Kevin Petti, Ph.D.
Departments of Natural Sciences,
Health, Exercise Science and Nutrition
San Diego Miramar College
Objectives
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Identify the four components of fitness
Identify basic heart anatomy and blood flow
Understand the following cardiodynamic
variables: systole, diastole, stroke volume,
cardiac output, ejection fraction, the cardiac
conducting system, blood pressure, and
venous return
Describe how these adapt to exercise
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Components of Fitness
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Cardiorespiratory Endurance
ν
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Muscular Strength
ν
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Maximum amount of force a muscle can exert during a
single contraction
Flexibility
ν
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Ability of heart, lungs and blood vessels to deliver O2 to
exercising muscles
Range of Movement (ROM) at a joint
Body Composition
ν
ν
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
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Right
Left
ν
ν
Anterior
Descending
Circumflex
Valves of the Heart
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Atrioventricular Valves
ν
Tricuspid Valve
λ
ν
Between RA and RV
Bicuspid/Mitral Valve
λ
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Between LA and LV
Semilunar Valves
ν
ν
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Pulmonary Valve
Aortic Valve
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Chordae tendineae and
papillary muscles
associated w/ AV Valves
Valves prevent the
regurgitation of blood
Valves open and close via
changes in chamber BP
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Cardiac Physiology Concepts
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Conducting System of the Heart
Electrocardiogram (ECG)
Cardiodynamics
ν
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EDV, ESV, SV, EJ, Q
Cardiac Output
λ
λ
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At rest vs. exercise
Trained vs. untrained
Blood Pressure
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Conducting System of the Heart
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The heart is autorhythmic beats w/o nervous stimulation
The cells responsible for initiating and distributing
the stimulus for cardiac contraction are the heart’s
conducting system
Comprised of
ν
ν
ν
Sinoartial (SA) Node
Atrioventricular (AV) Node
Conducting Cells
λ
λ
λ
AV Bundle
Bundle Branches (Bundle of His)
Purkinje Fibers
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The Electrocardiogram (ECG)
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Systole - chamber contraction
Diastole - chamber relaxation
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Cardiodynamics
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End-Diastolic Volume (EDV)
ν
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End-Systolic Volume (ESV)
ν
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Volume of blood in each ventricle at the end of
ventricular systole
Stroke Volume (SV)
ν
ν
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Volume of blood in each ventricle at the end of
ventricular diastole
Amount of blood ejected from each ventricle per beat
Can be expressed as EDV - ESV = SV
Ejection Fraction
ν
Percentage of EDV ejected in ventricular systole
Cardiodynamics
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Cardiac Output
Amount of blood ejected from each ventricle in
one minute
ν Perhaps the most important variable of cardiac
function
ν Can be expressed as below:
Q
=
Hr
x
SV
ν
Cardiac
Output
(ml/min)
Heart
Rate
(beats/min)
Stroke
Volume
(ml/beat)
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Cardiac Output at Rest
Q
=
Hr
Cardiac
Output
(ml/min)
Heart
Rate
(beats/min)
6000 ml/min =
or 6 l/min
75 bpm
x
SV
Stroke
Volume
(ml/beat)
x
80 ml/beat
Cardiac Output at rest equals 6 liters/minute
Average adult has ≈ 5 liters of blood
Cardiac Output During Exercise
Q
=
Hr
Cardiac
Output
(ml/min)
Heart
Rate
(beats/min)
13,440 ml/min =
or 13.4 l/min
120 bpm
x
SV
Stroke
Volume
(ml/beat)
x
112 ml/beat
Cardiac Output can more than double during moderate exercise
for 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 in
Response to Aerobic Training
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Resting heart rate decreases as a result of increased
fitness
What would this do to SV if Q remains constant?
This answer is a result of Starling’s Law that states
⇑EDV = ⇑ SV
SV ⇑ with training, so what happens to exercising
HR at a particular intensity (10 min. mile) as one
becomes more trained?
Factors Affecting Stroke Volume
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Factors Affecting Cardiac Output
Blood Pressure
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Systemic arterial pressure
ν
ν
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Mean Arterial Pressure (MAP) is most often used in
studies reporting a single blood pressure
ν
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Measured in mm Hg millimeters of mercury
Declines further from heart
1/3 of pulse pressure (systolic-diastolic) + diastolic pressure
Regulated closely by neural and hormonal
mechanisms; is a function of resistance to blood flow
Resistance is a function of vessel diameter, vessel
length, blood viscosity, blood turbulence
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Measuring Blood Pressure
systolic/diastolic
Blood Pressure
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Resting BP
≈120/80 mmHg
MAP =
93.3mm Hg
Exercising MAP
can exceed
113 mmHg
(200/70)
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Blood Pressure
and Venous Return
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BP at start of venous system is 1/10 of that at start
of 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 during
exercise
ν
Why is it important to cool down after aerobic exercise?
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