1. 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

2. 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

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

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

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

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

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

14. 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

15. 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

16. 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

17. 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

18. 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

19. 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

20. 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

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

22. 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

23. 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