•
•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
•
•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

msoFBDEA



Regulation of blood pressure
Short - term regulation
   -  baroreflex
Middle - term regulation
  -  humorals regulation
• sympathetic - catecholamines
• RAAS
• ADH
Long – term regulation
  -  kidney regulation

Short term regulation
 BAROREFLEX


original record of waves in circulatory parameters
(photoplethysmography by Peňáz)
obr11
Respiration
Blood flow
Blood pressure
Heart rate




SD
SD





840
828
760
756
808
856
768
780
808
756
708
728
756
732
708

x
y
x
y
x
y
x
y
x
y

•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

čas (s)
frekvence (Hz)
T=50 s
T=50 s
T=3 s
a=0.5
a=0.3
a=0.2
perioda  T
amplituda  a
frekvence  f = 1/T
f = 1/3 = 0.33 Hz
f = 1/10 = 0.1 Hz
f = 1/50 = 0.02 Hz
0.5
0.2
0.3
+
+
=
+
+
=
0.5
0.2
0.3
0.33
0.02
0.1
f = 0,02 Hz
f = 0,1 Hz
f = 0,33 Hz

High frequency rhythms (HF)
- respiration
Middle frequency rhythms (MF) - baroreflex
Very low frequency rhythms (VLF)
– e.g. Renin - angiotenzin -aldosteron system