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Control of Circulation and Arterial Pressure

Control of Circulation and Arterial Pressure. Chapter 6. Marijn Rolf. Introduction. Outline. Heart Autoregulation (Frank-Starling principle) Central Nerve System Organs Autoregulation Central Nerve System Complete Model Description. Heart – Autoregulation. Frank-Starling in short:

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Control of Circulation and Arterial Pressure

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  1. Control of Circulationand Arterial Pressure Chapter 6 Marijn Rolf

  2. Introduction

  3. Outline • Heart • Autoregulation (Frank-Starling principle) • Central Nerve System • Organs • Autoregulation • Central Nerve System • Complete Model Description

  4. Heart – Autoregulation Frank-Starling in short: ↑ venous return  cardiac output ↑

  5. Heart – Autoregulation Frank-Starling principle 1: With constant afterload the RV end-systolic volume is independent of the end-diastolic volume. ↑ venous return  RV output ↑

  6. Heart – Autoregulation Frank-Starling principle 2: The afterload of the RV is independent of the LA preload. The lungs compensate by using more capillaries. So: ↑ RV output  LV filling ↑

  7. Heart – Autoregulation Side effect of Frank-Starling: A higher pressure in the RA influences the depolarisation rate of the SA-node, resulting in an increased heartrate. So: ↑ venous pressure  heart rate ↑

  8. Heart – Central Nerve System Sympathetic nervesventriclesincreases heart rate and muscle contractility Parasympathic nerves (vagi)SA- and AV-node, atriadecreases heart rate

  9. Heart – Central Nerve System Control loop is closed by baroreceptors on large arteries.Rising arterial pressure excites the baroreceptors, followed by a decrease in sympathetic activity.

  10. Heart Model description: CO = HR * SV = HR * Kc * Pv

  11. Organs - Autoregulation Depends on the organs’ metabolic needs. Arteriolar vasodilation is caused by: • Decreased O2 concentration • Increased CO2 • Adenosine release (waste product of ATP)

  12. Organs – Central Nerve System Sympathetic activity (except in the brain)causes arteriolar vasoconstriction regulating mean arterial blood pressure

  13. Organs

  14. Organs Model

  15. Organs Model description CO = (Pa-Pv)/Rper ΔPv = -Ca/Cv* ΔPa ↓ ΔPa = Cv/(Cv +Ca)*Rper*ΔCO ΔPv = Ca/(Cv +Ca)*Rper*ΔCO

  16. Heart: Organs: CO = HR * SV = HR * Kc * Pv ΔPv = Ca/(Cv +Ca)*Rper*ΔCO Pv = Pm + Δ Pv Complete Model CO = Pm*HR*Kc 1+HR*Kc*Rper*Ca/(Ca+Cv)

  17. Reference Cardiovascular Physiology Concepts Richard E. Klabunde, Ph.D. http://www.cvphysiology.com

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