Cardiovascular Regulation and Integration Chapter 16 Cardiovascular Regulation and Integration Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

Intrinsic Regulation of Heart Rate Cardiac muscle has an inherent rhythm. The sinoatrial node Would generate a rate ~ 100 BPM Described as pacemaker Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

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 Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

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 Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

Extrinsic Regulation of Heart Rate and Circulation Chemical: circulate via blood Neural: direct innervation Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

Sympathetic and Parasympathetic Neural Input Operate in parallel Different structure pathways and transmitters Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

Sympathetic Influence Catecholamines Chronotropic: increases rate Inotropic: decreases rate Adrenergic fibers Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

Parasympathetic Influence Vagus nerves: cholinergic fibers Release ACh Slow HR As exercise begins, there is a decrease in parasympathetic activity. Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

Input from Higher Centers Central command: coordinates neural activity to regulate flow to match demands Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

Peripheral Input Chemoreceptors Mechanoreceptors Baroreceptors Monitor metabolites, blood gases Mechanoreceptors Monitor movement and pressure Baroreceptors Monitor blood pressure in arteries Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

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 Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

Distribution of Blood Predominantly directed by Vasodilation Vasoconstriction Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

Physical Factors Affecting Blood Flow Flow = Pressure gradient × Vessel radius4 Vessel length × Viscosity Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

Effect of Exercise At the start of exercise Dilation of local arterioles Vessels to nonactive tissues constrict Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

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+ Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

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. Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

Hormonal Factors Adrenal medulla releases Cause vasoconstriction Epinephrine Norepinephrine Cause vasoconstriction Except in coronary arteries and skeletal muscles Minor role during exercise Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition

Exercising After Cardiac Transplantation Depressed cardiac output Increased stroke volume Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition