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Regulation in Cardiovascular System: Types and Mechanisms

Explore the types and mechanisms of regulation in the cardiovascular system, including autoregulation, hormonal regulation, and neural regulatory mechanisms. Learn about key substances, hormones, and control centers that maintain blood pressure and tissue perfusion. Discover the integration of regulatory processes in the heart and vasculature to ensure optimal function and homeostasis. Understand the classification of blood pressure values and variability of circulatory parameters.

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Regulation in Cardiovascular System: Types and Mechanisms

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  1. Regulation in cardiovascularsystem

  2. Typesofregulation- generalview 2 basic types: • Nervousregulation • Humoralregulation • Feedback control - negative • - positive autoregulation – localregulation – systemregulation

  3. REGULATION IN CARDIOVASCULAR SYSTEM Mainfunction: • keeprelativelyconstantaneousarterialbloodpressure • Keepperfusionoftissues

  4. Regulationofvessels tone • Tone ofthevessels = basic tensionofthesmoothmuscleinsideofthewall (vasoconstriction x vasodilatation) • Regulation - localautoregulation - systemregulation

  5. Autoregulation Autoregulation – thecapacityoftissues to regulatetheirownbloodflow Myogenictheory – Baylissphenomenon (as thepressurerises, thebloodvessels are distended and thevascularsmoothmusclefibresthatsurroundthevesselscontract; thewalltensionisproportional to thedistendingpressuretimestheradiusofthevessels – lawofLaplace)

  6. Autoregulation • Metabolictheory–vasodilatorsubstancestend to accumulate in activetissue, and these metabolitesalsocontribute to autoregulation • endingproductsofenergeticmetabolism – CO2, lactate acid, K+ • effectofhypoxia(circulation: vasodilatation x pulmonarycirculation: vasoconstriction) • Adenosin – coronarycirculation: vasodilatation

  7. Autoregulation • by substanceswhichreleasingfrom: • endothelium • tissues

  8. Substancessecreted by the ENDOTHELIUM Vasodilatation: Nitric oxide (NO) fromendothelialcells (originallycalled: EDRF) Prostacyclinisproduced by endothelialcells Thromboxane A2 promotesplateletaggregation (importantprostacyclin – thromboxan balance) Vazoconstriction: Endothelins (polypeptids – 21peptides) threeisopeptides: ET 1, ET 2 , ET 3

  9. Substancessecreted by thetissues: Histamine –primarilytissuehormones. General affect: vasodilatation - decreaseperiphery resistence, bloodpressure KININS: 2 relatedvasodilatedpeptides Bradykinin + lysylbradykinin (kallidin). Sweatglands, salivaryglands 10x strongersthan histamine Relaxationofsmoothmuscle, decreasebloodpressure

  10. Systemicregulation By hormones Catecholamines – epinephrine, norepinephrine - effect as activationofsympatheticsystem RAAS - stress situation ADH - generalvasoconstriction Natriuretichormones - vasodilatation

  11. Neuralregulatorymechanism Autonomicnervoussystem Sympathetic: vasoconstriction Allbloodvesselsexceptcapillaries and venulescontainsmoothmuscle and receive motor nerve fibersfromsympatheticdivisionof ANS (noradrenergicfibers) • Regulationoftissuebloodflow • Regulationofbloodpressure Parasympathetic part: vasodilatation Onlysacralparasympatheticcholinergicfibres (Ach) inervatedarteriolsfromexternal sex organs

  12. INTEGRATION ofregulationin cardiovascularsystem Theregulationoftheheart: • Rami cardiaci n. vagi Cardiacdecelerator center - medula oblongata (ncl.dorsalis, ncl. ambiguus) – parasympatheticfibresofnervus vagus : vagal tone (tonicvagaldischarge) Negative chronotropiceffect (on heartrate) Negative inotropiceffect (on contractility) Negative dromotropiceffect (on conductivetissue)

  13. INTEGRATION ofregulationin cardiovascularsystem Theregulationoftheheart: • nn. cardiaci Cardiacaccelerator center – spinalcord, sympathetic ganglia – sympathetic NS Positive chronotropiceffect (on heartrate) Positive inotropiceffect (on contractility) Positive dromotropiceffect (on conductivetissue)

  14. INTEGRATION ofregulationin cardiovascularsystem Vasomotor centre (regulationforfunctionofvessels) Medula oblongata • presoric area (rostral and lateral part –vasoconstriction – increasebloodpressure • depresoric area (medio-caudalis part – vasodilatation, decreaseofbloodpressure)

  15. INTEGRATION ofregulationin cardiovascularsystem • Influence by centralnervoussystem • cerebralcortex • limbiccortex • hypothalamus

  16. Regulationofbloodpressure • Short - term regulation • - baroreflex • Middle - term regulation • - humoralsregulation • sympathetic - catecholamines • RAAS • ADH • Long – term regulation • - kidneyregulation

  17. Classification BP values AccordingtheGuidelinesofEuropean Society ofCardiology 2013

  18. Variability ofcirculatoryparameters • Heartrate • Bloodpressures – systolic and diastolic • variability expresses itsfluctuation around the average value at certain time intervals (or in various conditions)

  19. HeartRate Variability (HRV) • Informsusabout the activity of the vagus nerve (tonicactivityofn.vagus = vagal tone) • Timeanalysis: • fromHolter monitoring ECG or 5 - 30min records ECG • It is basically a statistical evaluation +/-standard deviation • Disables intervals differing by more than 20% from the average, thus further processed only normal(NN)intervals and evaluated by the standard deviation of all NN sequence for 24h

  20. Spectralanalysis: • Carried out under standard conditions at various maneuvers (supine, standing); evaluated with 300 representative intervals RR / NN / • Another mathematical processing (Fourier transform) -length RR intervals are converted to cycles in Hz • The spectrum is divided into several components - low (LF: the sympathetic modulation) and high frequency (HF: vagal modulation) • People with reduced heart rate variability have a 5 times higher risk of death

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