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11.05.08(b): Other Reflexes and Reflex Actions

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Slideshow is from the University of Michigan Medical School's M1 Cardiovascular / Respiratory sequence …

Slideshow is from the University of Michigan Medical School's M1 Cardiovascular / Respiratory sequence

View additional course materials on Open.Michigan:
openmi.ch/med-M1Cardio

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  • 1. Author(s): Louis D’Alecy, 2009License: Unless otherwise noted, this material is made available under the terms of theCreative Commons Attribution–Non-commercial–Share Alike 3.0 License:http://creativecommons.org/licenses/by-nc-sa/3.0/We have reviewed this material in accordance with U.S. Copyright Law and have tried to maximize your ability to use,share, and adapt it. The citation key on the following slide provides information about how you may share and adapt thismaterial.Copyright holders of content included in this material should contact open.michigan@umich.edu with any questions,corrections, or clarification regarding the use of content.For more information about how to cite these materials visit http://open.umich.edu/education/about/terms-of-use.Any medical information in this material is intended to inform and educate and is not a tool for self-diagnosis or areplacement for medical evaluation, advice, diagnosis or treatment by a healthcare professional. Please speak to yourphysician if you have questions about your medical condition.Viewer discretion is advised: Some medical content is graphic and may not be suitable for all viewers.
  • 2. Citation Key for more information see: http://open.umich.edu/wiki/CitationPolicyUse + Share + Adapt { Content the copyright holder, author, or law permits you to use, share and adapt. } Public Domain – Government: Works that are produced by the U.S. Government. (USC 17 § 105) Public Domain – Expired: Works that are no longer protected due to an expired copyright term. Public Domain – Self Dedicated: Works that a copyright holder has dedicated to the public domain. Creative Commons – Zero Waiver Creative Commons – Attribution License Creative Commons – Attribution Share Alike License Creative Commons – Attribution Noncommercial License Creative Commons – Attribution Noncommercial Share Alike License GNU – Free Documentation LicenseMake Your Own Assessment { Content Open.Michigan believes can be used, shared, and adapted because it is ineligible for copyright. } Public Domain – Ineligible: Works that are ineligible for copyright protection in the U.S. (USC 17 § 102(b)) *laws in your jurisdiction may differ { Content Open.Michigan has used under a Fair Use determination. } Fair Use: Use of works that is determined to be Fair consistent with the U.S. Copyright Act. (USC 17 § 107) *laws in your jurisdiction may differ Our determination DOES NOT mean that all uses of this 3rd-party content are Fair Uses and we DO NOT guarantee that your use of the content is Fair. To use this content you should do your own independent analysis to determine whether or not your use will be Fair.
  • 3. Other Reflexes and Reflex Actions M1 – Cardiovascular/Respiratory Sequence Louis D’Alecy, Ph.D.Fall 2008 3
  • 4. Wednesday 11/05/08, 10:00 Other Reflexes & Reflex Actions 22 slides, 50 minutes1. Valsalva maneuver2. Idiopathic Orthostatic Hypotension • (autonomic nervous system defect)3. Baroreceptor reset in hypertension4. Gravity (standing)5. Low pressure -volume (Bainbridge Reflex)6. Cardioinhibitory (Bezold-Jarisch Reflex)7. Cerebral ischemic (Cushing Reflex) 4
  • 5. Valsalva Maneuver: forced expiration against a closed glottisIntrathorasic Pressure or 2 4 1 3 Source Undetermined 5
  • 6. Valsalva Maneuver:1 Increased MAP due to increased intrathorasic pressure(ITP)2 MAP & PP decrease due to decreased VR3 Baro-R increase in HR & VC (little effect) STOP FORCED EXPIRATION4 Decrease ITP, Increase VR &PP, Baro-R, decrease HR 6
  • 7. Image of arterial baroreceptor removed Please see: http://mor.phe.us/jtw/ Gateway/Projects/Vertebrates/ images/EvolutionOfTheHeart/ ArterialBaroreceptors.gifMcGraw-Hill 7
  • 8. Hypertension resets baroreceptors toRegulate pressure at a higher set point.Frequency ofActionPotentials Source Undetermined 8
  • 9. No Baro-Reflex Source UndeterminedIdiopathic Orthostatic Hypotension (autonomic defect) Deep anesthesia and over inflation of lungs Restricts VR and decreases preload. 9
  • 10. M&H Fig. 10.2Pattern of pressures in recumbent individual 90 mmHg Mohrman and Heller. Cardiovascular Physiology. McGraw-Hill, 2006. 6th ed. 10
  • 11. Pattern of pressures upon standing No Baro-R Hydrostatic YET ! column Pooling 5 + 90= 95 In veins 95 + 90=185 Mohrman and Heller. Cardiovascular Physiology. McGraw- Hill, 2006. 6th ed. 11
  • 12. VC VC Mohrman and Heller. Cardiovascular Physiology. McGraw-Hill, 2006. 6th ed.VC = vasoconstriction or venoconstriction 12
  • 13. One-way valves Mohrman and Heller. Cardiovascular Physiology. McGraw-Hill, 2006. 6th ed. 13
  • 14. Contraction of skeletal leg muscles breaks the Hydrostatic ColumnLeg muscles relaxed: Image of man’s Leg musclesPressure due to body with leg contracted: Pressure musclesgravity=80 mmHg contracted due to gravity=14 removed mmHg 14
  • 15. M&H 10.2 Mohrman and Heller. Cardiovascular Physiology. McGraw-Hill, 2006. 6th ed. 15
  • 16. Bainbridge Reflex: Increase stretch of low pressure receptorscauses a reflex increase in heart rate and cardiac output. Source UndeterminedIn a normally hydratedindividual the “excess”volume is sensed byvenous side low pressurereceptors and reflexlyincreases HRand CO (Bainbridge reflex)favoring removal of excessfluid on the arterial side byrenal mechanisms. 16
  • 17. Arterial baroreceptor reflex: A increase stretch (pressure) causesa reflex decrease in heart rate (negative chronotropic effect) . Source UndeterminedIn a dehydrated (patient)individual the volumereplacement increasesCO and producesincreasedMAP and a reflexbradycardia.Used as test of “Howdry?” 17
  • 18. Volume status determines the heart rate response to “volume expansion”. “NORMAL”“NORMAL” Source Undetermined 18
  • 19. Other Cardiovascular Reflexes (Resetting of Set Point ? Pathophysiology ? )Bezold-Jarisch Reflex -respond to chemostimulation in myocardium by veratrum alkaloids -may be “pharmacological curiosity” BUT -***bradycardia with hypotension*** -over rides arterial baroreceptor reflex !! -vagal afferents -atropine blockable -may have role in posterior-inferior infarctsAnesthesiology 2003; 98:1250-1260 19
  • 20. Other Cardiovascular Reflexes (Resetting of Set Point ? )Cushing (Cerebral Ischemic Reflex) -response to compressive ischemia in CNS -marked increase in arterial blood pressure -over rides arterial baroreceptor reflex !! -may involve central chemoreceptors -presumed to be “protective” of ischemic CNS 20
  • 21. When intracranial pressure approaches arterial pressure the Cushing reflex produces a sustained Increase in arterial blood pressure. Cerebral Ischemic ReflexNormal CSF Pressure Source Undetermined 21
  • 22. If time permits And not to be testedCardiovascular Response to Exercise 22
  • 23. McGraw-Hill 23
  • 24. Strenuous Exercise Skeletal MuscleMohrman and Heller. Cardiovascular Physiology. McGraw-Hill, 2006. 6th ed. M&H 10.4 24
  • 25. 25McGraw-Hill
  • 26. Additional Source Information for more information see: http://open.umich.edu/wiki/CitationPolicySlide 5: Source UndeterminedSlide 7: McGraw-HillSlide 8: Source UndeterminedSlide 9: Source UndeterminedSlide 10: Mohrman and Heller. Cardiovascular Physiology. McGraw-Hill, 2006. 6th ed.Slide 11: Mohrman and Heller. Cardiovascular Physiology. McGraw-Hill, 2006. 6th ed.Slide 12: Mohrman and Heller. Cardiovascular Physiology. McGraw-Hill, 2006. 6th ed.Slide 13: Mohrman and Heller. Cardiovascular Physiology. McGraw-Hill, 2006. 6th ed.Slide 15: Mohrman and Heller. Cardiovascular Physiology. McGraw-Hill, 2006. 6th ed.Slide 16: Source UndeterminedSlide 17: Source UndeterminedSlide 18: Source UndeterminedSlide 21: Source UndeterminedSlide 23: McGraw-HillSlide 24: Mohrman and Heller. Cardiovascular Physiology. McGraw-Hill, 2006. 6th ed.Slide 25: McGraw-Hill