Regulation of Regulation of blood flowblood flow

Decrease of tone of precapillary sphincters

Decrease of tone of precapillary sphincters

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

Dilatation of arteriolesDilatation of arterioles

Increase of blood flow in organsIncrease 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 linkCharacteristic 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 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.

Central part in regulation of vascular tone

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 cortexRole of brain cortex and hypothalamus and hypothalamus in regulation of blood flowin 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.

NorepinephrineEpinephrineEpinephrine

Action with β-adrenoreceptors of

vessel wall

Action with β-adrenoreceptors of

vessel wall

Dilation of vessels

Dilation of vessels

Spasm of vessels of skeen,

digestive organs, kidney and lungs

Spasm of vessels of skeen,

digestive organs, kidney and lungs

Peculiarities of influences of catecholamine on the diameter of vessels

Adrenal gland medulla

Action with α-adrenoreceptors of vessel wall

Action with α-adrenoreceptors of vessel wall

Dilation of vessels of muscles,

brain, heart

Dilation of vessels of muscles,

brain, heart

Action with α-adrenoreceptors of vessel wall

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.

RenninRennin––aangiotensin--aaldosteron system

Angiotensinogen

Cells of liverUxta glomerular

cell of kidney

Rennin

Angiotensin І

Angiotensin ІІ

Angiotensin converting enzyme

Angiotensin ІІІ

Adrenal glands

AldosteronReabsorbtion

of water in kidneys

Increase of water in body

Vascular spasm

Increase of arterial pressure

Role of renninennin––aangiotensin--aaldosteron 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 renninrennin––angiotensinangiotensin--aldosteron systemaldosteron system ..

Change the body pose from vertical to horizontalChange the body pose from vertical to horizontal

Increase of blood flow to heartIncrease of blood flow to heart

Increase the stroke volumeIncrease the stroke volume

Increase of impulsation from mechanoreceptors of aortic arcIncrease of impulsation from mechanoreceptors of aortic arc

Activation of depressor part of vasomotor centerActivation of depressor part of vasomotor center

Inhibition of pressor part of vasomotor centerInhibition of pressor part of vasomotor center

Decrease of frequency and force of heart beat, dilation of vessels Decrease of frequency and force of heart beat, dilation of vessels

ChangesChanges of blood flowof blood flow in the clinostatic posein the clinostatic pose

Change the body pose from horizontal to verticalChange the body pose from horizontal to vertical

Depo of blood in the vein of down part ofbodyDepo of blood in the vein of down part ofbody

Decrease of blood flow to heartDecrease of blood flow to heart

Decrease of stroke volume Decrease of stroke volume

Decrease of impulsation from mechanoreceptors of aortic arc Decrease of impulsation from mechanoreceptors of aortic arc

Activation of pressor part of vasomotor centerActivation of pressor part of vasomotor center

Increase of frequency and force of heart beat, vascular spasm Increase of frequency and force of heart beat, vascular spasm

ChangesChanges of blood flowof blood flow in the orthostatic posein the orthostatic pose

Regulation of blood flow in physical

exercises

In physical exercises In physical exercises impulses from pyramidal impulses from pyramidal neurons of motor zone in neurons of motor zone in cerebral cortex passes both cerebral cortex passes both to skeletal muscles and to skeletal muscles and vasomotor center. Than vasomotor center. Than through sympathetic through sympathetic influences heart activity and influences heart activity and vasoconstriction are vasoconstriction are promoted. Adrenal glands promoted. Adrenal glands also produce adrenalin and also produce adrenalin and release it to the blood flow. release it to the blood flow.

Proprioreceptor activation Proprioreceptor activation spread impulses through spread impulses through interneurons to sympathetic interneurons to sympathetic nerve centers. So, nerve centers. So, contraction of skeletal contraction of skeletal muscle during exercise muscle during exercise compress blood vessels, compress blood vessels, translocate blood from translocate blood from peripheral vessels into heart, peripheral vessels into heart, increase cardiac output and increase cardiac output and increase arterial pressure.increase arterial pressure.

Bleeding

Decrease of filtration in kidneys glomerulus's

Decrease of impulsation from mechanoreceptors and increase from chemo receptors of aorta arc

and carotid sinus

Decrease of impulsation from mechanoreceptors and increase from chemo receptors of aorta arc

and carotid sinus

Activation of rennin-angiotensin-aldosteron

system

Activation of pressor part of vascular-

motor centre

Activation of pressor part of vascular-

motor centre

Increase of influences of sympathetic

nervous on heart

Increase of influences of sympathetic

nervous on heart

Increase of heart beat and the strength of heart contraction

Increase of heart beat and the strength of heart contraction

Spasm of vessels and decrease of capacity of circulatory bed

Spasm of vessels and decrease of capacity of circulatory bed Angiotensin ІІ

Increase of Na+ and water

reabsorbtion

Increase of Volume of Blood Circulation

Renew of blood flow in the case of bleedingRenew of blood flow in the case of bleeding

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Normotonic type of cardio-vascular reaction on the physical load

This type of set ifwhen the rise in heart rate is in  60-80%, and increasesystolic blood pressure  does not exceed 30% at lowdiastolic blood pressureto 20% of the original condition. at  The percentage increase in pulse-On pressure must meet the percentagement increase in heart rate. Duration of-restorative period shall not exceed-schuvaty 3 min. Let us consider for-arbitrary normotonichnoyu reaction  when the rate of change of blood pressure and heart rate re-exceeds normative values , butrecovery period ends to 3 minutes.

Interpretation

% 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

HypotonicHypotonic typetype of cardio-vascular of cardio-vascular reaction on the physical loadreaction on the physical load (Functional

insufficiency of heart)

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For hypotonic reaction is characterized by a significant increase in heart rate (by 120-150%) with a moderate increase in SBP and unchanged or slight increase in DBP relative to the initial state, which leads to little marked increase in pulse pressure (by 12-15%).

The percentage increase in PA does not match the percentage increase in heart rate. The duration of the recovery period for this type of reaction than 3 minutes.

Hypertonic type of cardio-vascular reaction

on the physical load ((Functional insufficiency of heart Functional insufficiency of heart

and blood vessels. Predictor of arterial hypertensionand blood vessels. Predictor of arterial hypertension))

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This reaction is characterized by a significant increase in heart rate (< 120% ) relative to the initial state . Systolic blood pressure increased to 180-190 mmHg. century. (50% ).

Diastolic pressure is increased and maintained higher than the initial state for all time the recovery period . Return parameters to their original values takes more than 3 minutes. Let us consider the reaction of hypertension in the case when the growth SAP is within 30-40%, with an increase in DAP of 10-15% relative to the initial state .

Restoration of blood pressure and heart rate also lasts for more than 3 minutes. HR SAP DAP

DistonicDistonic typetype of cardio-vascular of cardio-vascular reaction on the physical loadreaction on the physical load ((Functional Functional

insufficiency of blood vessels. Predictor of autonomic distony)insufficiency of blood vessels. Predictor of autonomic distony)

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This reaction set in when the heart rate increases to 100% of the initial state with a sharp fall DBP, until the emergence of the phenomenon of no-taper t .

Pulse pressure as a result of growing adequately percentage increase in heart rate. Systolic blood pressure increased moderately (up to 40-60% of the original state).

Recovery targets for this type of reaction lasts more than 3 minutes.

HR SAP DAP

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StepStep typetype of cardio-vascular reaction on the of cardio-vascular reaction on the

physical loadphysical load ( (Functional insufficiency of regulatory apparatuses of blood flow)

The response of a stepped increase SAT characterized in that the 2nd and 3rd minute recovery period SBP rises above what it was at 1 minute.

Duration restore all parameters than 3 minutes. It is believed that this type points to a functional deficiency of regulatory mechanisms of the cardiovascular system.

HR SAP DAP

Cardiovascular Adjustments to Exercise

Fetal Circulation

No circulation to lungs Foramen ovale Ductus arteriosum

Circulation must go to placenta Umbilical aa., vv.

Adult remnants of fetal circulationAdult remnants of fetal circulation

Adult Fetus

Fossa ovale Foramen ovale

Ligamentum arteriosum Ductus arteriosus

Medial umbilical ligaments Umbilical aa.(within fetus)

Round ligament (ligamentum teres) of liver

Umbilical v.(within fetus)

Ligamentum venosum Ductus venosus

Medial umbilical ligament Umbilical cord (leaving fetus)

Hepatic Portal System

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