Download Heart Rate X Stroke Volume

THIRD EDITION
HUMAN PHYSIOLOGY
AN INTEGRATED APPROACH
Dee Unglaub Silverthorn, Ph.D.
Chapter 14, part B
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
Autorhythmic Cells: Initiation of Signals
• Pacemaker membrane potential
• I-f channels Na+ influx
• Ca++ channels – influx, to AP
• Slow K+ open – repolarization
PLAY
Animation: Cardiovascular System: Cardiac Action Potential
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Autorhythmic Cells: Initiation of Signals
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
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Coordinating the Pump: Electrical Signal Flow
• AP from autorhythmic cells in sinoatrial node
(SA)
• Spreads via gap junctions down internodal
pathways and across atrial myocardial cells
(atrial contraction starts)
• Pause – atrioventricular (AV) node delay
• AV node to bundles of His, branches & Perkinje
fibers
• Right and left ventricular contraction from apex
upword
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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
PLAY
Animation: Cardiovascular System: Intrinsic Conduction System
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
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
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Electrocardiogram (ECG):
Electrical Activity of the Heart
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Figure 14-21: The electrocardiogram
ECG Information Gained
• (Non-invasive)
• Heart Rate
• Signal conduction
• Heart tissue
• Conditions
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Figure 14-24: Normal and abnormal electrocardiograms
Heart 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
PLAY
Animation: Cardiovascular System: The Cardiac Cycle
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Heart 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
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Heart Cycle
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 14-25: Mechanical events of the cardiac cycle
Summary of Heart Beat:
Electrical, Pressure and Chamber Volumes
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
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
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Regulators of the Heart: Reflex Controls of Rate
Figure 14-28: Reflex control of heart rate
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
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%)
PLAY
Animation: Cardiovascular System: Cardiac Output
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Cardiac Output: Heart Rate X Stroke Volume
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 14-26: The Wiggers diagram
Regulators of the Heart:
Factors Influencing Stroke Volume
• Starlings Law – stretch
• Force of contraction
• Venous return:
• Skeletal pumping
• Respiratory pumping
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Regulators of the Heart:
Factors Influencing Stroke Volume
Figure 14-29: Length-force relationships in the intact heart
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Regulators of the Heart:
Factors Influencing Stroke Volume
Figure 14-31: Factors that affect cardiac output
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Summary
• Anatomy and physiology of the Heart , its
chambers, muscles, valves, and its pacemaker
• Mechanism of cardiac muscle stimulation and
contraction
• Blood vessels and fluid flow down a pressure
gradient
• Electrical control of the beat sequence, and ECG
information
• Influence of beat rate and stroke volume by ANS
and hormones
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings