Download Regulation of systemic circulation

Regulation of systemic
circulation
Influences of metabolic products on
the diameter of vessels
Increase of Н+ ions,
pyroveniger and lactic acids,
decrease of pO2 and increase
of pCO2 in tissues
Decrease of tone of precapillary
sphincters
Dilatation of arterioles
Increase of blood flow in organs
Basal tone of vessels
• Smooth muscles of vessels wall don’t relax whole. It all time has
some tension – muscular tone. Tonic condition is connect with
changes of electrical characteristic and some contraction of muscles.
Tone of smooth muscles support by two mechanisms: myogenic and
neuro-humoral. Miogenic regulation play the main role in the
support of vessel tone. When
absent all nervous and humoral
influences, present vessel tone or basal tone.
• In the base of basal tone is possibility of some smooth cells to the
spontaneously activity and spread of excitation from cell to cell; it
provide rhythmical changing of tone. It present in arterioles,
precapillares sphincters. Influences, which decrease level of
membrane potential, increase frequency of spontaneously impulses
and amplitude of contraction of smooth muscles. Hyper polarization
of membrane leads to disappeared of spontaneously excitability and
muscles contraction.
Role of mechano- and chemoreceptor in
regulation of the vessels tone
•From mechanoreceptors of
aorta arc sensory
information transmit by left
depressor (aortic) nerve,
brunch of n.vagus to the
medulla oblongata.
•Excitation from
mechanoreceptors of carotid
sinus zone lead by Sino
carotid nerve (brunch of
glossopharingeal nerve) to
the medulla oblongata.
Characteristic of afferent link
Sensory innervations of heart and vessels is present by nerve ending.
Receptors divided by it function on mechanoreceptors, which are reacted
on the changing of arterial pressure and chemo receptors, which are
reacted on the changing of chemical composition of blood. Irritation for
mechanoreceptors is the speed and level of tissues stretching by increase
or pulse wave of blood pressure.
Angioreceptors are present at all vessel system and have the whole
receptor field, it maximal presents at the main reflector zones: aortic,
sino-carotid, in the vessels of pulmonary cycle of the blood circulation. At
the answer on the each systolic increase of arterial pressure,
mechanoreceptors of that zones generate impulses, which disappeared in
the diastolic decrease of pressure. Minimal threshold of excitation of
mechanoreceptors is 40 mm Hg, maximal is 200 mm Hg. Increase of
pressure higher than that level don’t lead to addition increase of
impulsation.
Central part in regulation of vascular tone
Central mechanisms, which regulate
connection between level of cardiac output and
tone of vessels, working by help of complex of
nervous structures, which named vasomotor
center. Structures of vasomotor center are
present in spinal cord, medulla oblongata,
hypothalamus, cortex of big hemisperes.
Spinal level of regulation is in the lateral
root of thoracic and lumbar segments and
consist of nervous cells, axons of which
produce the vasculoconstrictors fibers. That
neurons support their level of excitation by
help of impulses from higher structures of
nervous system.
Vasomotor center of medulla oblongata is the main center of
regulation of blood flow. It located on the bottom of 4 ventricle, in it
upper part. Vasomotor center divided on pressor and depressor
zones.
Pressor zone support increase of arterial pressure. It connect with
the increase of tone of resistive vessels. Also increase frequency and
strength of heart contraction and as result minute volume of blood
flow.
Regulatory influences of neurons of pressor zone act by help of
increase of tone of sympathetic nervous system on heart and vessels.
Depressor zone support decrease of arterial pressure, heart work.
It is the place of changes the impulses, which are coming from
mechanoreceptors of reflector zones and cause central inhibition of
tonic impulses of vasoconstrictors. Parallel the information from that
zone by help of parasympathetic nerves go to heart. As result,
decrease work and stroke volume of blood.
Also, depressor zone act reflector inhibition of pressor zone.
Role of brain cortex and hypothalamus
in regulation of blood flow
Centers of hypothalamus give the descendent influences on the
vasomotor center of medulla oblongata. In hypothalamus present
depressor and pressor zones. That is why hypothalamic level give the
same double reaction as bulbar center. Posterolateral part of
hypothalamus cause excitation of vasomotor center. Anterior part of
hypothalamus can cause mild inhibition of one.
Some zones of cortex also give the descendent influences on the
vasomotor center of medulla oblongata. Motor cortex excites
vasomotor center. Anterior temporal lobe, orbital areas of frontal
cortex, cingulated gyrus, amygdale, septum and hippocampus can also
control vasomotor center.
That influences form as a result of compare the information, which
enter in higher part of nervous system from different receptor zones. It
support realization of cardio-vascular component of emotions, reaction
of behavior.
Nervous efferent link of
regulation of vascular tone
Neural mechanism of efferent regulation of blood flow act by
- Preganglionic sympathetic neurons, body of which present in
the anterior root of thoracic and lumbar part of spinal cord and
postganglionic neurons, which are present in para- and prevertebral
sympathetic ganglion.
- Preganglionic parasympathetic neurons of nucleus of n. vagus,
nucleus of pelvic nerve, which present in sacral part of spinal cord,
and their postganglionic neurons.
- For hole visceral organs is efferent neurons of metasympathetic
nervous system, which are present in the intamural ganglion of
their wall.
All neurons is the end way from efferent and central influences,
which throught the adrenergic, cholinergic and other mechanism of
regulation act on heart and vessels.
Peculiarities of influences of catecholamine on the
diameter of vessels
Adrenal gland medulla
Epinephrine
Action with
β-adrenoreceptors of
vessel wall
Dilation of
vessels
Norepinephrine
Action with αadrenoreceptors of
vessel wall
Dilation of
vessels of
muscles,
brain, heart
Action with αadrenoreceptors of vessel
wall
Spasm of vessels
of skeen,
digestive organs,
kidney and lungs
Influences of chatecholamines and
vasopressin on the vessel tone
• Influences of chatecholamines from adrenal glands determined by
presents of different kinds of adrenoreceptors – α and β. Connection of
hormones with α–adrenoreceptors act constriction of vessel wall, with
β–adrenoreceptor - relaxation.
Adrenalin connect with α– and β–adrenoreceptor, nor epinephrine
with α–adrenoreceptor. Adrenalin has strong action on vessels. On
artery and arterioles of skin, digestive organs, kidneys and lungs it has
constrictive influences; on the vessels of skeletal muscles, brain and
heart - dilatatory. On the physical load, emotional load it increase blood
flow through skeletal muscles, brain and heart.
Vasopressin (antidiuretic hormone) cause spasm of artery and
arterioles of organs of abdominal cavity and lungs. But vessels of brain
and heart reacted on that hormone by dilatation, which help increase
the nutrition of brain and heart.
Rennin–angiotensinaldosteron system
Cells of liver
Uxta glomerular
cell of kidney
Angiotensinogen
Rennin
Angiotensin І
Angiotensin converting enzyme
Angiotensin ІІ
Vascular spasm
Angiotensin ІІІ
Increase of arterial pressure
Adrenal glands
Aldosteron
Reabsorbtion
of water in
kidneys
Increase of water
in body
Role of rennin–angiotensin-aldosteron
system in regulation of vessel tone
Uxta glomerular cells of kidney produce enzyme rennin as the answer of
decrease of kidneys perfusion or increase of influences of sympathetic nervous
system. It convert angiotensinogen, which produced in liver, in Angiotensin І.
Angiotensin І, by the influences of angiotensin converting enzyme in the vessel
of lung, converted in angiotensin II. Angiotensin ІІ has strong
vasculoconstrictor influences. It can explain of presents of sensory to
angiotensin II receptors in precapillary arterioles. Very big dose of angiotensin
II can cause the spasm of vessels of heart and brain. Increase of rennin and
angiotensin in blood increase the thirst (need to drink water). Also angiotensin
II or angiotensin III, stimulate the production of aldosteron. Aldosteron, which
produce in the cortex of adrenal glands, increase reabsorbtion of sodium in
kidneys, salivary glands, digestive system, and change the sensation of vessel
walls to the influences of epinephrine and norepinephrine. This is the rennin–
angiotensin-aldosteron system .
Changes of blood flow in the clinostatic pose
Change the body pose from vertical to horizontal
Increase of blood flow to heart
Increase the stroke volume
Increase of impulsation from mechanoreceptors of aortic arc
Activation of depressor part of vasomotor center
Inhibition of pressor part of vasomotor center
Decrease of frequency and force of heart beat, dilation of vessels
Changes of blood flow in the orthostatic pose
Change the body pose from horizontal to vertical
Depo of blood in the vein of down part ofbody
Decrease of blood flow to heart
Decrease of stroke volume
Decrease of impulsation from mechanoreceptors of aortic arc
Activation of pressor part of vasomotor center
Increase of frequency and force of heart beat, vascular spasm

Regulation of
blood flow in
physical
exercises

In physical exercises impulses
from pyramidal neurons of
motor zone in cerebral cortex
passes both to skeletal muscles
and vasomotor center. Than
through sympathetic influences
heart activity and
vasoconstriction are promoted.
Adrenal glands also produce
adrenalin and release it to the
blood flow.
Proprioreceptor activation
spread impulses through
interneurons to sympathetic
nerve centers. So, contraction of
skeletal muscle during exercise
compress blood vessels,
translocate blood from
peripheral vessels into heart,
increase cardiac output and
increase arterial pressure.
Renew of blood flow in the case of bleeding
Bleeding
Decrease of impulsation from mechanoreceptors
and increase from chemo receptors of aorta arc
and carotid sinus
Increase of influences
of sympathetic
nervous on heart
Activation of pressor
part of vascularmotor centre
Decrease of filtration in
kidneys glomerulus's
Activation of rennin-
angiotensin-aldosteron
system
Increase of Na+
Increase of heart
Spasm of vessels and
and water
beat and the strength decrease of capacity
Angiotensin ІІ reabsorbtion
of heart contraction
of circulatory bed
Increase of Volume of Blood
Circulation
Normotonic type of cardio-vascular
reaction on the physical load
%
90
80
70
60
50
40
30
20
10
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Interpretation

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

% of increase heart beat - % of increase pulse pressure (increase
systolic AP and decrease of diastolic AP)
This is rational reaction, because in the case of
heart beat increase also increase pulse pressure
and stroke volume of blood.
Increase of systolic pressure is the
increase of systole of left ventricle
Decrease of diastolic pressure is decrease
of arteriole tonus, that help of better
supply of the blood on periphery
Hypotonic type of cardio-vascular
reaction on the physical load
%
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100
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
Functional
insufficiency of
heart
Hypertonic type of cardio-vascular
reaction on the physical load
140
%
120
100
80
60
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Functional
insufficiency of
heart and blood
vessels. Predictor of
arterial
hypertension.
Distonic type of cardio-vascular
reaction on the physical load
160
%
140
120
100
80
60
40
20
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-20ВС
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-60
-80
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-100
-120
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Functional
insufficiency of
blood vessels.
Predictor of
autonomic distony.
Step type of cardio-vascular
reaction on the physical load
100
%
80
60
40
20
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Functional
insufficiency of
regulatory
apparatuses of
blood flow.
Cardiovascular Adjustments
to Exercise


Fetal Circulation
No circulation to lungs


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Foramen ovale
Ductus arteriosum
Circulation must go to
placenta

Umbilical aa., vv.
Adult remnants of fetal circulation
Adult
Fetus
Fossa ovale
Foramen ovale
Ligamentum arteriosum
Ductus arteriosus
Medial umbilical ligaments
Umbilical aa.(within fetus)
Round ligament
Umbilical v.(within fetus)
(ligamentum teres) of liver
Ligamentum venosum
Ductus venosus
Medial umbilical ligament
Umbilical cord (leaving fetus)
Hepatic Portal System
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