• •2 basic types: üNervous regulation üHumoral regulation üFeedback control - negative ü - positive ü • autoregulation – local regulation – system regulation •Main function: • • keep relatively constantaneous arterial blood pressure •Keep perfusion of tissues • •Tone of the vessels = basic tension of the smooth muscle inside of the wall • (vasoconstriction x vasodilatation) • •Regulation - local autoregulation • - system regulation •Autoregulation – the capacity of tissues to regulate their own blood flow •Myogenic theory – Bayliss phenomenon (as the pressure rises, the blood vessels are distended and the vascular smooth muscle fibres that surround the vessels contract; the wall tension is proportional to the distending pressure times the radius of the vessels – law of Laplace) • •Metabolic theory – vasodilator substances tend to accumulate in active tissue, and these metabolites also contribute to autoregulation –ending products of energetic metabolism – CO2, lactate acid, K+ –effect of hypoxia (circulation: vasodilatation x pulmonary circulation: vasoconstriction) –Adenosin – coronary circulation: vasodilatation • •by substances which releasing from: – endothelium – tissues • •Substances secreted by the ENDOTHELIUM •Vasodilatation: •Nitric oxide (NO) from endothelial cells •(originally called: EDRF) •Prostacyclin is produced by endothelial cells • •Thromboxane A2 promotes platelet aggregation •(important prostacyclin – thromboxan balance) •Vazoconstriction: • Endothelins (polypeptids – 21peptides) • three isopeptides: ET 1, ET 2 , ET 3 •Substances secreted by the tissues: •Histamine – primarily tissue hormones. •General affect: vasodilatation - decrease periphery resistence, blood pressure • •KININS: 2 related vasodilated peptides •Bradykinin + lysylbradykinin (kallidin). •Sweat glands, salivary glands •10x strongers than histamine •Relaxation of smooth muscle, decrease blood pressure • • •By hormones •Catecholamines – epinephrine, norepinephrine - effect as activation of sympathetic system •RAAS - stress situation •ADH - general vasoconstriction •Natriuretic hormones - vasodilatation •Autonomic nervous system •Sympathetic: vasoconstriction •All blood vessels except capillaries and venules contain smooth muscle and receive motor nerve fibers from sympathetic division of ANS (noradrenergic fibers) -Regulation of tissue blood flow -Regulation of blood pressure •Parasympathetic part: vasodilatation •Only sacral parasympathetic cholinergic fibres (Ach) inervated arteriols from external sex organs • •The regulation of the heart: –Rami cardiaci n. vagi •Cardiac decelerator center - medula oblongata (ncl.dorsalis, ncl. ambiguus) – parasympathetic fibres of nervus vagus • : vagal tone (tonic vagal discharge) • •Negative chronotropic effect (on heart rate) •Negative inotropic effect (on contractility) •Negative dromotropic effect (on conductive tissue) • •The regulation of the heart: – nn. cardiaci •Cardiac accelerator center – spinal cord, sympathetic ganglia – sympathetic NS • •Positive chronotropic effect (on heart rate) •Positive inotropic effect (on contractility) •Positive dromotropic effect (on conductive tissue) • • •Vasomotor centre (regulation for function of vessels) •Medula oblongata ü presoric area (rostral and lateral part –vasoconstriction – increase blood pressure ü üdepresoric area (medio-caudalis part – vasodilatation, decrease of blood pressure) • • • •Influence by central nervous system – cerebral cortex – limbic cortex – hypothalamus Regulation of blood pressure Short - term regulation - baroreflex Middle - term regulation - humorals regulation • sympathetic - catecholamines • RAAS • ADH Long – term regulation - kidney regulation Classification BP values category Systolic BP Diastolic BP (mmHg) (mmHg) optimal < 120 < 80 normal 120 – 129 80 – 84 high normal pressure 130 – 139 85 – 89 Hypertension - mild 140 – 159 90 – 99 Hypertension - moderate 160 – 179 100 – 109 Hypertension - severe ≥ 180 ≥ 110 Izolated systolic hypertension ≥ 140 < 90 According the Guidelines of European Society of Cardiology 2013 Variability of circulatory parameters •Heart rate •Blood pressures – systolic and diastolic • • •variability expresses its fluctuation around the average value at certain time intervals (or in various conditions) Heart Rate Variability (HRV) •Informs us about the activity of the vagus nerve (tonic activity of n.vagus = vagal tone) •Time analysis: •from Holter 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 •Spectral analysis: •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