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Chapter 16

Chapter 16. Cardiovascular Regulation and Integration. Intrinsic Regulation of Heart Rate. Cardiac muscle has an inherent rhythm. The sinoatrial node Would generate a rate ~ 100 BPM Described as pacemaker. Heart’s Electrical Activity.

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Chapter 16

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  1. Chapter 16 Cardiovascular Regulation and Integration McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

  2. Intrinsic Regulation of Heart Rate • Cardiac muscle has an inherent rhythm. • The sinoatrial node • Would generate a rate ~ 100 BPM • Described as pacemaker McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

  3. Heart’s Electrical Activity • Electrochemical rhythms spread from SA node across atria to atrioventricular (AV) node. • AV node causes a slight delay of ~ 0.1 s. • Allows ventricles to fill • AV bundle (bundle of His) • Right and left bundle branches • Purkinje system McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

  4. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

  5. Electrocardiogram (ECG) • A recording of the heart’s electrical activity • A standard system of lead placement has established known wave patterns. • P wave • QRS complex • T wave McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

  6. Extrinsic Regulation of Heart Rate and Circulation • Chemical: circulate via blood • Neural: direct innervation McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

  7. Sympathetic and Parasympathetic Neural Input • Operate in parallel • Different structure pathways and transmitters McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

  8. Sympathetic Influence • Catecholamines • Chronotropic: increases rate • Inotropic: decreases rate • Adrenergic fibers McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

  9. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

  10. Parasympathetic Influence • Vagus nerves: cholinergic fibers • Release ACh • Slow HR • As exercise begins, there is a decrease in parasympathetic activity. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

  11. Input from Higher Centers • Central command: coordinates neural activity to regulate flow to match demands McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

  12. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

  13. Regulation of the CV System McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

  14. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

  15. Peripheral Input • Chemoreceptors • Monitor metabolites, blood gases • Mechanoreceptors • Monitor movement and pressure • Baroreceptors • Monitor blood pressure in arteries McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

  16. Carotid Artery Palpation • HR is often monitored using the carotid arteries. • Pressure on baroreceptors may decrease HR. • Alternatives include • HR monitor • Radial or temporal pulse McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

  17. Distribution of Blood • Predominantly directed by • Vasodilation • Vasoconstriction McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

  18. Physical Factors Affecting Blood Flow Flow = Pressure gradient × Vessel radius4 Vessel length × Viscosity McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

  19. Effect of Exercise • At the start of exercise • Dilation of local arterioles • Vessels to nonactive tissues constrict McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

  20. Effect of Exercise • At rest, only 1 of every 30 – 40 capillaries is open in skeletal muscle. • During exercise, capillaries open and increase perfusion and O2 delivery. • Vasodilation mediated by – Temp – pH – CO2– Adenosine – NO – K+ – MG+ McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

  21. Nitric Oxide (NO) • Produced and released by vascular endothelium • NO spreads through cell membranes to muscle within vessel walls, causing relaxation. • Net result is vasodilation. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

  22. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

  23. Hormonal Factors • Adrenal medulla releases • Epinephrine • Norepinephrine • Cause vasoconstriction • Except in coronary arteries and skeletal muscles • Minor role during exercise McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

  24. Exercising After Cardiac Transplantation • Depressed cardiac output • Increased stroke volume McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

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