1 / 19

Exercise and the Heart

Exercise and the Heart. Q increase is in direct proportion to the O2 demand of the muscles Heart Rate Stroke Volume Blood pressure Systolic Diastolic a-v O2 Difference. O2 Delivery. Redistribution of Blood Flow. Muscle blood flow to working skeletal muscle

xanti
Download Presentation

Exercise and the Heart

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Exercise and the Heart

  2. Q increase is in direct proportion to the O2 demand of the muscles Heart Rate Stroke Volume Blood pressure Systolic Diastolic a-v O2 Difference O2 Delivery

  3. Redistribution of Blood Flow • Muscle blood flowto working skeletal muscle • Splanchnic blood flow to less active organs (Liver, kidneys, GI tract, etc.)

  4. Redistribution of Blood Flow During Exercise Fig 9.19 (c) 2004 The McGraw-Hill Companies, Inc. All rights reserved.

  5. Redistribution of Blood Flow

  6. Increased Blood Flow to Skeletal Muscle During Exercise • How? • Withdrawal of sympathetic vasoconstriction • Autoregulation • Blood flow increased to meet metabolic demands of tissue • Vasodilation:  O2 tension,  CO2 tension, pH, potassium, adenosine, nitric oxide

  7. Circulatory Responses to Exercise • Depend on: • Type, intensity, and duration of exercise • Environmental condition • Emotional influence

  8. Transition From Rest  Exercise and Exercise  Recovery • Rapid increase in HR, SV, cardiac output • Plateau in submaximal (below lactate threshold) exercise • O2 supply = O2 demand • Recovery depends on: • Duration and intensity of exercise • Training state of subject

  9. O2 supply = O2 demand Transition From Rest  Exercise  Recovery O2 supply < O2 demand

  10. Recovery • O2 supply > O2 demand • What is the extra oxygen used for? • Restore O2 inside muscles (myoglobin) • Removal of lactic acid • Reduce body temperature

  11. Incremental Exercise • Heart rate and cardiac output • Increases linearly with increasing work rate • Reaches plateau at 100% VO2max • Systolic blood pressure • Increases with increasing work rate

  12. Incremental Exercise • Stroke Volume • Reaches plateau at 40-60% VO2max • Why?

  13. Arm vs. Leg Exercise • At the same oxygen uptake arm work results in higher: • Heart rate • Due to higher sympathetic stimulation • Blood pressure • Due to vasoconstriction of large inactive muscle mass .

  14. Heart Rate and Blood Pressure During Arm and Leg Exercise

  15. Prolonged Exercise • Cardiac output is maintained • Gradual decrease in stroke volume • Gradual increase in heart rate • Cardiovascular drift • Due to dehydration and increased skin blood flow (rising body temperature) Fig 9.22 .

  16. HR, SV, and CO During Prolonged Exercise Fig 9.22

  17. Cardiovascular Adjustments to Exercise Fig 9.23

  18. Summary of Cardiovascular Control During Exercise • Initial signal to “drive” cardiovascular system comes from higher brain centers • Fine-tuned by feedback from: • Chemoreceptors • Mechanoreceptors • Baroreceptors Fig 9.24

  19. A Summary of Cardiovascular Control During Exercise Fig 9.24

More Related