Our hearts have evolved to be extremely efficient, long-lasting pumps that exquisitely match the needs of our bodies. This book is about how the heart does this; how can a heart pump the blood for up to 100 years while the best Formula 1 racing engine has a working life measured in hours? Why is the heart so efficient, and how are worn out parts replaced while working? How does it generate the force to act as a pump, how is it controlled electrically, and how can it repair itself? This book addresses these questions from physiological and molecular perspectives in language that aims to be accessible to all interested in biology and with liberal illustrations. The story of how the heart works is presented in the context of its origins: How is the heart formed in the womb? How it evolved as an oxygen pump through many configurations following the onset of oxygenic photosynthesis 2.5 billion years ago? Why its intimate co-evolution with the circulation and blood was essential to enable its efficiency and longevity? The book begins with a discussion of why the word heart is universally used as a metaphor for reason and emotion and traces its origins in modern and ancient languages. The last chapter offers advice on how to preserve the heart by matching our lifestyles more closely to how it evolved.
Author(s): Desmond J Sheridan
Publisher: World Scientific Publishing
Year: 2022
Language: English
Pages: 493
Contents
Preface
About the Author
Acknowledgements
Chapter 1 Not Just a Pump: Giving Life to Emotion
The Origin of Heart
Heart Metaphors
Heart in European Languages
Romance and Germanic
Uralic and Basque languages
Heart in Non-European Languages
The Uses of Heart in Ancient Languages
The Heart in Chinese
The Heart in Chinese Medicine
The Heart in Chinese Culture
Heart Metaphors Expressing Emotion
Mesopotamia
The Heart in Mesopotamian Medicine
Heart in Mesopotamian Culture
Ancient Egypt
The Heart in Egyptian Medicine
Heart in Egyptian Culture
Heart Metaphors in Ancient Egypt
The Concept of Heart in 21st Century Culture
Heart in Religion
The Physical and Metaphorical Heart: Why We Need Both
Conclusion
References
Appendix I
Appendix II
Appendix III
Appendix IV
Appendix V
Appendix VI
Chapter 2 Origins of the Heart
Starting Life with a Clean Slate
Development of the Heart
Genetic Control of Heart Development
Drosophila Hearts
Development of Vertebrate Heart
Evolution of the Four-Chambered Heart
Molluscs
Fish
Amphibians
Reptiles
Development of the Four-Chambered Heart in Mammals
Division of the atrio-ventricular canal
Division of the primitive atrium
Division of the primitive ventricle and outflow tract
Formation of the heart valves
Mitral and tricuspid valves
Aortic and pulmonary valves
Malformations of the heart
Surgical treatment of cardiac malformations
Genetics of the Four-Chambered Heart
Conclusion
References
Chapter 3 Molecular Motors
Regulation of the Heart
External regulation
Internal regulation
Frank–Starling response
The Anrep effect
Force frequency response
Structure of the Heart
Molecular Motor Structure
Myosin heavy chains
Myosin light chains
Origins of Actin and Myosin
Actin
Myosin
Anatomy of Cross Bridge Interaction
Tropomyosin
Troponin
Myosin light chains
Myosin binding protein-C (MyBP-C)
Titin
Operation of the Heart Motor
Cross bridge interaction
Activation
Actin myosin cyclic interaction
Regulation of the myosin–actin cycle
Autonomic Regulation of the Heart
Autonomic control of the molecular motor of the heart
Sympathetic nerves within the heart
Adrenergic signalling
Protein Kinase A Modulation of the Heart’s Motor
PKA control of the Ca2+ transient
PKA modulation of actin–myosin cross bridge interaction
Conclusion
References
Chapter 4 An Intelligent Pump
Bio-communication
Modes of communication
Resting membrane potential
Ion pumps
Osmotic control and electrochemical gradients
Action potentials
Regulation of calcium ions
Ca2+ and action potentials signals
Origin of Ca2+ signalling
Ca2+ regulates contraction
The origin of action potentials
Voltage-gated ion channels
The origin of voltage-gated ion channels
Voltage-gated ion channels in heart cells
How did action potentials evolve?
Action potentials in the heart
Electrical Anatomy of the Heart
Sinus node and atrial activation
Atrio ventricular node
The bundle of His
Bundle branches
Cell-to-cell conduction
Velocity of propagation
Specialisation of cardiac action potentials
Ventricular action potentials
Depolarisation
Early repolarisation and the early transient outward K+ current (Ito)
Inward calcium current Ica
Late repolarisation and outward potassium currents
Atrial action potentials
Purkinje fibre action potentials
Atrioventricular node cells
Sinus node
Diastolic depolarisation
The role of IKf in diastolic depolarisation
The role of periodic SR Ca2+ in sinus node cells
Maintaining a Normal Heart Rhythm
A dominant pacemaker
Managing multiple pacemaker cells
Abnormal pacemaker function
Refractoriness
Orderly conduction
The problem of re-entry
Conclusions
References
Chapter 5 A Pump for Life: In Good Times and in Bad
Working Within Its Limitations
Physiological adaptability
Circulatory responses to exercises
Distribution of blood flow during exercise
Regional blood flow during exercise
Local Regulation of Muscle Blood Flow
Direct muscle pump effects
Vascular conductance
Haemodynamic forces acting on blood vessels
Flow-mediated dilatation
EDRF and nitric oxide
Transduction of shear stress
Perfusion of the Heart During Exercise
Feed-forward control
Feedback control
Retrograde conducted response
Physical Adaptability
Regulation of heart size
Hypertrophy
Pregnancy-induced hypertrophy
Exercise-induced hypertrophy
Isometric and isotonic exercise
Hypertrophy as a compensatory mechanism
Is exercise-induced hypertrophy harmful?
Development and regression of hypertrophy
Exercise hypertrophy in older hearts
Long-term effects of physiological hypertrophy
Pathological Hypertrophy
Pressure overload
Volume overload
Hypertrophic cardiomyopathy
Long-term effects of overload hypertrophy
Morphology of LVH
Inter-myocyte connections
Coronary circulation
Coronary morphology
Haemodynamic effects on coronary perfusion
Heart Failure
Hypertrophy transition to heart failure
Maintenance and Regeneration of the Heart
Servicing the heart
The ubiquitin-proteasome system
Autophagy
Calpain system
Protein turnover and muscle growth
Can the heart regenerate?
Regeneration by proliferation of existing myocytes
Polyploidy
Conclusion
References
Chapter 6 Broken Hearts: Repair and Recovery
Broken Heart Syndrome: A Heart Metaphor with Cardiac Consequences
Lonely Hearts
Heart Attack
A 20th Century Epidemic
Heart Attack Symptoms
Diagnosis
The Electrocardiogram
Blood Tests
Atherosclerosis
Myocardial Ischaemia
Coronary Thrombosis
Acute Coronary Syndromes
Myocardial Infarction
Complications of MI
Sudden Cardiac Death
Cardiogenic Shock
Cardiac Rupture
Evolving Infarction
Pathophysiology
Myocardial Response to Injury
Inflammation
Inflammation in Myocardial Infarction
PAMPs and DAMPs
Pro-inflammatory Phase
Cytokines and Chemokines
Endothelial Cells
Neutrophils
Monocytes
Monocyte Functions
Repair and Proliferative Phase
New Growth
Fibroblasts
Therapeutic Intervention in the Inflammatory Response in MI
Stem Cell Interventions in MI
Conclusions
References
Appendix I
Danger associated molecular patterns
Appendix II
Pattern recognition receptors
Chapter 7 Roots and Branches
Evolution of the Circulation
Coelomic Circulation
Blood-based Vascular Systems
Open Circulatory Systems
Closed Circulatory Systems
Vertebrates
Anatomy of the Circulation
Pulsatile Pumping
Non-linear Elasticity
Structure of Arteries
Invertebrate Arteries
Microfibrils and Elastic Fibre Assembly
Resistance Arteries
Muscular Arteries
Blood Pressure Regulation
Vascular remodelling
Conductive arteries
Resistance arteries
Capillary filtration and transport
Blood brain barrier
Neurovascular unit
The Circulation’s Reservoir
Passive changes in venous capacity
Active changes in venous capacity
Conclusions
References
Chapter 8 Intelligent Tubes
Introduction
Intelligent Tubes in the Circulation
Myogenic Tone
Smooth Muscle
Contractile Function
Length Adaptability
Smooth Muscle Structure
Cell structure
Smooth muscle cytoskeleton
Intermediate filaments
Actin–myosin filaments
Dense bodies
A Dynamic Cytoskeleton
Smooth Muscle Contraction
Actin–myosin configuration in SMCs
Bi-polar and side-polar myosin
Actin–myosin interaction in SMCs
Activation of smooth muscle contraction
Signalling Pathways Regulating Contraction
Multiple Interacting Controls
Vasoactive agonist stimulation
Mechano-sensing in Blood Vessels
Flow mediated dilatation
Stretch induced contraction — Myogenic tone
Sensing stretch
Stretch-induced depolarisation
Evolution of Muscle
Smooth Muscle Cells are Flexible in Structure and Function
Actin Binding Proteins
Smooth muscle tropomyosin
Caldesmon
Calponin and PKC mediated contraction
Tropomyosin: A Master Actin Filament Regulator
Smooth Muscle Length Adaptability
Dynamic actin polymerisation
Dynamic myosin polymerisation
Conclusions
References
Chapter 9 Heart and Blood: Co-evolved Intimate Partners
Introduction
Composition of Blood
Transport Medium
Oxygen Consumption
Oxidation of the Earth’s Atmosphere
Photosynthesis
Atmospheric oxygen and the evolution of complex life forms
Complex Organisms Needed More Efficient Oxygen Delivery
Evolution of Oxygen Use
Oxygen Transport
Haemocyanins
The structure of haemocyanins
Haemerythrins
Haemoglobin
Structure of haemoglobins
Synthesis of haemoglobin
Haem synthesis
Globin synthesis
Regulation of haemoglobin production
Haemoglobin and Oxygen Transport
Cooperative and allosteric binding
In Vivo Modulation of Haemoglobin Oxygen Affinity
The Bohr effect
The Haldane effect
2,3-Bisphosphoglyceric acid
Evolution of Haemoglobin and Erythrocytes: Matching the Heart and Circulation
Why Are Capillaries and Erythrocytes of Similar Size?
Erythrocyte structure, blood viscosity and the heart
Factors affecting viscosity of blood
The Fåhræus–Lindqvist effect
Co-evolution of Erythrocytes and Haemoglobin
Biconcave Disc Erythrocytes
Erythrocyte Size, Metabolic Activity and Genome Size
Diminution of Capillaries and Erythrocytes in Mammals and Bird
Conclusions
References
Chapter 10 Preserving the Heart
Introduction
Diets Then and Now
Physical Activity Then and Now
Tobacco and Alcohol Then and Now
Cardiovascular Disease Then and Now
Diabetes Then and Now
Obesity Then and Now
Blood Pressure Then and Now
Impact of Lifestyle Changes on Longevity
Learning from the Past
What and How We Eat
Dietary Modification to Reduce Cardiovascular Disease
Mediterranean diet
Individual and Population Dietary Challenges
Physical Activity and Cardiovascular Health
Physical Activity Guidelines
Any Is Good, the More the Better
Physical Activity for Life
Tobacco and the Heart
The Health Burden of Tobacco
Recollections of an Ex-smoker
Working Towards a Tobacco-free World
Alcohol and the Heart
Can We Drink Safely?
Summary and Conclusions
References
Index
