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THIRD EDITION
HUMAN PHYSIOLOGY
AN INTEGRATED APPROACH
Dee Unglaub Silverthorn, Ph.D.
Chapter 14
Cardiovascular Physiology
PowerPoint® Lecture Slide Presentation by
Dr. Howard D. Booth, Professor of Biology, Eastern Michigan University
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
About this Chapter
• Blood flow pumping & distribution
• Anatomy and histology of the heart
• Mechanism of cardiac contraction
• Heart beat sequence–how the pump works
• Regulators of hear beat and volume pumped
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Overview of the Cardiosvascular System
• Heart and Blood vessels
• Products transported to sustain all cells
Table 14-1: Transport in the Cardiovascular System
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Circulation Reviewed
• Heart – "four chambered"
• Right atrium & ventricle
•
Pulmonary circuit
• Left atrium & ventricle
•
Systemic circuit
• Blood Vessels – "closed circulation"
• Arteries –from heart
• Capillaries– cell exchange
• Veins – to heart
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Circulation Reviewed- it’s a closed circuit but “stuff” can get into the circuit in
two places; which ones?
What is the general
rule regarding
the direction of blood
flow through blood
vessels?
(capillaries, veins,
arteries)
What is the exception
to this general rule?
Figure 14-1: Overview of circulatory system anatomy
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Why does blood flow? Think physics. . .
• P__________ G__________
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What’s this mean?
• Pressure Gradient
What cardiovascular structure
generates this pressure gradient?
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The heart; why is the left side of the heart
hypertrophied compared to the right side?
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Blood Flow: Pressure Changes
Figure 14-2 : Pressure gradient in the blood vessels
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Some Physics of Fluid Movement: Blood Flow
• Flow rate: (L/min)
• Flow velocity
= rate/C-S area of vessel
• Resistance slows flow
• Vessel diameter
(radius)
• Blood viscosity
• Tube length
• Which 2 above are
relatively
constant?
Figure 14-4 c: Pressure differences of static and flowing fluid
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• Blood viscosity and tube length are basically
constant.
• Vessel diameter has the most influence on blood
flow.
• So now we understand 2 factors effecting blood
flow; 1. Pressure gradient and 2. Resistance
(VESSEL DIAMETER, tube length, blood viscosity)
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How velocity of blood flow is effected by crosssectional area (A)
Figure 14-6: Flow rate versus velocity of flow
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Heart Structure – anatomy review
•
Which two veins return
deoxygenated blood to the
heart? Which chamber is this,
RA, LA, RV, LV?
•
Deoxygenated blood is pumped
to the lungs via what blood
vessel?
•
Oxygenated blood returns to
the heart by what blood vessel?
• To which chamber?
•
Name the 4 heart valves.
•
What are chordae tendinae?
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Figure 14-7 g: ANATOMY SUMMARY: The Heart
Cardiac Muscle Cells:
• Myocardial Autorhythmic Cells
• Membrane potential “never rests”
pacemaker potential.
• Myocardial Contractile Cells
• Have a different looking action
potential due to calcium channels.
• General cardiac cell stuff:
• Intercalated discs
• Allow branching of the
myocardium
• Gap Junctions (instead of synapses)
• Fast Cell to cell signals
• Many mitochondria
• Large T tubes
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Figure 14-10: Cardiac muscle
Mechanism of Cardiac Contractile Cell Muscle
Excitation, Contraction & Relaxation
Figure 14-11: Excitation-contraction coupling and relaxation in cardiac muscle
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Modulation of Contraction
• Graded Contraction: proportional to crossbridges
formed
• More [Ca++]: crossbridges, more force & speed
• Under catecholemine control:
• Norepinephrine
• Epinephrine
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Modulation of Contraction- what is the key ion?
Figure 14-12: Modulation of cardiac contraction by catecholamines
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Action potential
of a cardiac
contractile cell
What is the
Main difference
Between this and
The neuron
Action potential?
There is a
Physiological
Reason for this
difference; what
Could it be?
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• A longer (time duration) action potential means
there will be a longer
• R______ P_______
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Refractory period
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• So what does a longer action potential PREVENT
in the myocardium?
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• Summation and tetanus! We don’t want tetany in
our myocardium.
• A myocardium in a state of tetanus ceases to be a
pump.
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Autorhythmic Cells: Initiation of Signals
• Pacemaker membrane potential
• I-f channels Na+ influx
• Ca++ channels – influx, to AP
• Slow K+ open – repolarization
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Action potentials of Autorhythmic Cells: Pacemaker
potential; FUNNY Ca++ CURRENTS
Depolarization due to calcium NOT sodium!
Figure 14-16: Action potentials in cardiac autorhythmic cells
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Sympathetic and Parasympathetic
• Sympathetic – speeds heart rate by  Ca++ & I-f
channel flow
• Parasympathetic – slows rate by  K+ efflux & 
Ca++ influx
Figure 14-17: Modulation of heart rate by the nervous system
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Coordinating the Pump: Electrical Signal Flow
Figure 14-18: Electrical conduction in myocardial cells
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Coordinating the Pump: Electrical Signal Flow
Figure 14-19a: Electrical
conduction in the heart
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CLEAR!
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Electrocardiogram (ECG):
Electrical Activity of the Heart
• Einthoven's
triangle
• P-Wave –
atria
• QRS- wave –
ventricles
• T-wave –
repolarization
Figure 14-20: Einthoven’s triangle
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Electrocardiogram (ECG):
Electrical Activity of the Heart
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Figure 14-21: The electrocardiogram
Electrical events of the
cardiac cycle
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Mechanical events of the cardiac cycle:
Heart Chambers and the Beat Sequence
1. Late diastole: all chambers relax, filling with
blood
2. Atrial systole: atria contract, add 20% more
blood to ventricles
3. Isovolumic ventricular contraction: closes AV
valves ("lub"), builds pressure
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Cardiac Cycle: Finish and Around To the Start
4. Ventricular ejection: pushes open semi lunar
valves, blood forced out
5. Ventricular relaxation: aortic back flow slams
semi lunar valves shut ("dup")
AV valves open refilling starts – back to start of
cycle
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Cardiac Cycle; mechanical events
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Figure 14-25: Mechanical events of the cardiac cycle
Cardiac cycle: events in the left ventricle
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Figure 14-26: The Wiggers diagram
QUIZ, 8 questions
Match the following segments to the corresponding
ventricular events.
1.
2.
3.
4.
AB
BC
CD
DA
(a)
(b)
(c)
(d)
Ejection of blood into aorta
Isovolumic contraction
Isovolumic relaxation
Passive filling and atrial contraction
___
___
___
___
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Quiz
Match the following events to points A –D
on the figure.
Aortic valve opens
Mitral valve opens
Aortic valve closes
Mitral valve closes
5. A __________________
6. B ___________________
7. C __________________
8. D __________________
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Summary of Heart Beat:
Electrical, Pressure and Chamber Volumes
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Figure 14-27: The Wiggers diagram
Regulators of the Heart: Reflex Controls of Rate
• Range: about 50 – near 200
• Typical resting: near 70
• AP conduction
• Muscle Contraction
• Parasympathetic slows
• Sympathetic speeds
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Cardiac Output: Heart Rate X Stroke Volume
• Around 5L :
(72 beats/m  70 ml/beat = 5040 ml)
• Rate: beats per minute
• Volume: ml per beat
• EDV - ESV
• Residual (about 50%)
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Regulators of the Heart:
Factors Influencing Stroke Volume
• Starlings Law – stretch
• Force of contraction
• Venous return:
• Skeletal pumping
• Respiratory pumping
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Regulators of the Heart:
Factors Influencing Stroke Volume
Figure 14-29: Length-force relationships in the intact heart
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Regulators of the Heart:
Factors Influencing Stroke Volume
Figure 14-31: Factors that affect cardiac output
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