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BP = CO x TPR

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  1. BP = CO x TPR (stroke volume x heart rate) BP = blood pressure CO = cardiac output TPR = Total peripheral resistance

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  3. Plateau Ascending limb 70 Normal, rest 5 10 15 ‘The energy of contraction - - - is proportional to the muscle fibre length at rest. Starling’s law of the heart (1914) (Arterial pressure held constant) Stroke volume (human) ml Central venous pressure (mmHg) Filling pressure The ’ventricular function curve’ or ‘Starling curve’

  4. How are RV and LV stroke volumes kept equal? 10

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  7. Laplace´s law states that, for a hollow sphere, the internal pressure (P) is proportional to the wall tension (T) and is inversely proportional to the internal radius (r): 2T P = r Tension is a force equal to wall stress (S) times Wall thickness (w): 2Sw P = r Increasing the radius reduces the curvature, and therefore the inward component of the wall stress, so pressure falls. 14

  8. The Laplace effect and the Frank-Starling mechanism clearly have opposite effects on ventricular performance: Distension of the ventricle raises its force of contraction – due to Starling´s law X Distension also reduces the pressure generated by a given contractile force – due to Lapace´s law. Fortunately, under physiological conditions (i.e. in a healthy heart) the gain in contractile energy resulting from Moderated distension (Starling´s law) greatly outweighs the fall in pressure-generating efficiency (Laplace´s law) In contrast, the failing heart is often grossly dilated, making the Laplace effect the dominant one. An increase in radius in an already swollen heart causes little to no increase in contractile force, because the ventricle is on the plateau of the Starling curve, but the increase in radius impairs the generation of systolic pressure and hence ejection (Laplace´s law). Reduction of cardiac distension is an important therapeutic goal in heart failure

  9. ∆P = CVP - RAP CVP= central venous pressure RAP = right atrial pressure ∆P = pressure difference (i.e. driving force) for the return of blood from the periphery to the right atrium. Thus, the cardiac output steadily rises as RAP falls.

  10. Change in the venomotor tone, by constriction or dilatation of only veins, is equivalent to change in the blood volume. Because most of the blood volume is in the veins, a pure increase in venomotor tone would be equivalent to a blood transfusion.

  11. Because arterioles contain only minor fraction of the blood volume, changes in the arteriolar tone have only little effect on MSFP and thus on the x-intercept. However, changes in the arteriolar tone can have a marked effect on the CVP

  12. Normal situation ∆P = CVP – RAP = 6 mmHg – 2 mmHg = 4 mmHg venous return 5 L/min (1.25 L/1 mmHg) Vasodilatation ∆P = CVP – RAP = 8 mmHg - 2 mmHg = 6 mmHg venous return 7.5 L/min (6 x 1.25)

  13. ∆P = CVP - RAP Cardiac output: • By sucking the right atrium dry, it will tend to lower RAP. • By pumping blood out of the heart towards the veins, it will increase CVP. Thus, the only way to produce a permanent change in cardiac output, venous return and RAP is to change at least one of the two function curve

  14. Akutní mechanizmy regulace krevního tlaku 1.Arteriální baroreflex 2. Arteriální chemoreceptory 3. Bainbridgeův reflex 4. Ischemické receptory CNS

  15. Normální Procenta výskytu Denervovaný 50 100 150 200 250 Střední arteriální tlak (mmHg)

  16. „Normální“  I „Znovu nastavený“ Počet impulzů (impulz/sek)  P 100 Arteriální tlak (mmHg)

  17. Akutní mechanizmy regulace krevního tlaku 1. Arteriální baroreflex 2. Arteriální chemoreceptory 3. Bainbridgeův reflex 4. Ischemické receptory CNS

  18. Akutní mechanizmy regulace krevního tlaku 1. Arteriální baroreflex 2. Arteriální chemoreceptory 3. Bainbridgeův reflex 4. Ischemické receptory CNS

  19. “The first slide of the lecturer, who was an intrepid young cardiovascular physiologist, was Figure 1 from Guyton and Coleman´s epic paper. It was clear that the audience was already becoming nervous. There was some whispering, shuffling, and a sense of unease. The lecturer´s second slide was met with a more definite response. There was derision, laughter, and spontaneous comments from the audience….. I witnessed, for the only time in my academic life, a lecturer being chased from the podium by the audience” Christopher S. Wilcox

  20. Vazodilatace Vazokonstrikce

  21. Filtration, Reabsorption and Excretion Rates of Different Substances by the Kidneys Amount Amount Amount % of Filtered Filtered Reabsorbed Excreted Load Reabsorbed Glucose 180 180 0 100 (g/day) Bicarbonate 4 320 4 318 2 99.9 (mmol/day) Sodium 25 560 25 410 150 99.4 (mmol/day) Chloride 19 440 19 260 180 99.1 (mmol/day) Potassium 756 664 92 87.8 (mmol/day) Creatinine 1.8 0 1.8 0 (g/day)

  22. Autoregulation of Glomerular Filtration Rate and Renal Blood Flow • Myogenic Mechanism • Tubuloglomerular Feedback

  23. Příjem nebo vylučování sodíku (x normálu) Equilibrium Renálně perfuzní tlak (mmHg)

  24. EquilibriumB Příjem nebo vylučování sodíku (x normálu) EquilibriumA Renálně perfuzní tlak (mmHg)

  25. A B Příjem nebo vylučování sodíku (x normálu) Equilibrium Renálně perfuzní tlak (mmHg)

  26. Příjem nebo vylučování sodíku (x normálu) EquilibriumA Equilibrium B Renálně perfuzní tlak (mmHg)