Physiology of heart. Physiology of heart. Physiological bases of Physiological bases of

hemo dynamic.hemo dynamic.

AutomatismAutomatism

Active potentialActive potential of contractiveof contractive heart cellsheart cells

Phases of active potentialPhases of active potential

0 – 0 – depolarizationdepolarization 1 – 1 – beginning rapid beginning rapid

repolarizationrepolarization 2 – 2 – slowly repolarization or slowly repolarization or

plateauplateau 3 – 3 – ending rapid ending rapid

repolarizationrepolarization 4 – 4 – rest periodrest period..

4 – 4 – absolute absolute refractivityrefractivity; ;

5 – 5 – relative relative refractivityrefractivity; ;

6 – 6 – period of period of increase increase excatabilityexcatability;;

7 - 7 - exaltationexaltation

Active potential, contraction, excitability of Active potential, contraction, excitability of heart cells heart cells

2 – 2 – SA nodeSA node; ;

3 – 3 – Bachman tractBachman tract; ;

4 – 4 – tracts of tracts of BachmanBachman, , VenkebachVenkebach,,

TorelTorel

6 –6 – AV node AV node

7 – 7 – Hiss bungleHiss bungle

8 – 8 – right leg of Hiss bungleright leg of Hiss bungle

9 – 9 – anterior brunch of left leg of anterior brunch of left leg of Hiss bungleHiss bungle

10 – 10 – posterior brunch of left leg of posterior brunch of left leg of Hiss bungleHiss bungle

11 - Kent bungle11 - Kent bungle

12 – 12 – Jams bungleJams bungle

13 - 13 - Meacham bungleMeacham bungle

Conductive system of heartConductive system of heart

Cardiac cycleCardiac cycle Systole Systole

1. period of tension1. period of tension asynchrony contractionasynchrony contraction isometric contractionisometric contraction (all valves are closed) (all valves are closed) 2. period of ejection2. period of ejection protosphigmic interval protosphigmic interval

(opening of semilunear valves)(opening of semilunear valves) fast ejectionfast ejection slow ejectionslow ejection

Cardiac cycle Cardiac cycle DiastoleDiastole

1. Period of relaxation1. Period of relaxation protodiastolic interval (closing of protodiastolic interval (closing of

semilunear valves)semilunear valves) phase of isometric relaxation phase of isometric relaxation

(opening of AV-valves is end of this phase)(opening of AV-valves is end of this phase) 2. Period of filling2. Period of filling phase of rapid fillingphase of rapid filling phase of slow fillingphase of slow filling phase of filling by help of atrium phase of filling by help of atrium

systole systole

Heart sounds. ComponentsHeart sounds. Components I tone.I tone. 1. 1. Valve component (AV Valve component (AV

valves)valves). . 2. 2. Muscle componentMuscle component.. 3. 3. Vessels componentVessels component

(opening of semilunear valves)(opening of semilunear valves) 4. Atrium component4. Atrium component.. II tone. 1. II tone. 1. Valve componentValve component

(closing of semilunear valves)(closing of semilunear valves) 2. 2. Vessels componentVessels component..

EchocardiographyEchocardiography

1. M-measure1. M-measure 2. D-measure2. D-measure 3. Doppler3. Doppler 4. Contrasting4. Contrasting

Effects of thyroid hormonesEffects of thyroid hormones

Thyroid hormones increase transmission Thyroid hormones increase transmission process in ribosome and nucleus of cells. process in ribosome and nucleus of cells. Intracellular enzymes are stimulated due Intracellular enzymes are stimulated due to increasing protein synthesis. Also to increasing protein synthesis. Also increases glucose absorption and uptake increases glucose absorption and uptake of glucose by cells, increases glycolisis and of glucose by cells, increases glycolisis and gluconeogenesis. In blood plasma gluconeogenesis. In blood plasma increases contents of free fatty acids. increases contents of free fatty acids.

All these effects of thyroid hormones lead All these effects of thyroid hormones lead to increase activity of mitochondria in to increase activity of mitochondria in heart cells and ATP formation in it. So, heart cells and ATP formation in it. So, both activity of heart muscle and both activity of heart muscle and conduction of impulses are stimulated.conduction of impulses are stimulated.

Effects of adrenocortical Effects of adrenocortical hormoneshormones

Aldosterone causes increasing Na+ and Cl- Aldosterone causes increasing Na+ and Cl- in blood and decreases K+. This is actually in blood and decreases K+. This is actually for producing action potential in the heart. for producing action potential in the heart. Cortisol stimulates gluconeogenesis and Cortisol stimulates gluconeogenesis and increase blood glucose level. increase blood glucose level.

Amino acids blood level and free fatty acids Amino acids blood level and free fatty acids concentration in blood increases also. concentration in blood increases also. Utilization of free fatty acids for energy Utilization of free fatty acids for energy increases. These mechanisms actual in increases. These mechanisms actual in stress reaction. So heart activity is stress reaction. So heart activity is stimulated.stimulated.

Hormones of Langerhans’ Hormones of Langerhans’ islets effectsislets effects

Insulin promotes facilitated diffusion of glucose into Insulin promotes facilitated diffusion of glucose into cells by activation glucokinase that phosphorilates cells by activation glucokinase that phosphorilates glucose and traps it in the cell, promotes glucose glucose and traps it in the cell, promotes glucose utilization, causes active transport of amino acids utilization, causes active transport of amino acids into cells, promote translation of mRNA in ribosome into cells, promote translation of mRNA in ribosome to form new proteins. Also insulin promotes glucose to form new proteins. Also insulin promotes glucose utilization in cardiac muscle, because of utilization utilization in cardiac muscle, because of utilization fatty acids for energy. fatty acids for energy.

Clucagone stimulate gluconeogenesis, mobilizes Clucagone stimulate gluconeogenesis, mobilizes fatty acids from adipose tissue, promotes utilization fatty acids from adipose tissue, promotes utilization free fatty acids foe energy and promotes free fatty acids foe energy and promotes gluconeogenesis from glycerol. So both hormones gluconeogenesis from glycerol. So both hormones can increase strength of heartbeat.can increase strength of heartbeat.

Endocrine function of heartEndocrine function of heart

Myocardium, especially in heart Myocardium, especially in heart auricles capable to secretion of auricles capable to secretion of regulatory substances as atria Na-regulatory substances as atria Na-ureic peptide, which increases loss of ureic peptide, which increases loss of Na+ in increase of systemic Na+ in increase of systemic pressure, or digitalis-like substances, pressure, or digitalis-like substances, which can stimulate heart activity.which can stimulate heart activity.

Effects of nn. vagiEffects of nn. vagi

Effects of nn. vagus on the Effects of nn. vagus on the heart activity. heart activity. Parasympathetic stimulation Parasympathetic stimulation causes decrease in heart causes decrease in heart rate and contractility, rate and contractility, causing blood flow to causing blood flow to decrease. decrease.

It is known as negative It is known as negative inotropic, dromotropic, inotropic, dromotropic, bathmotropic and bathmotropic and chronotropic effect. chronotropic effect.

Effects of acetylcholineEffects of acetylcholine Effects of acetylcholin leads to increase of K+ Effects of acetylcholin leads to increase of K+

permeability through cell membrane in permeability through cell membrane in conductive system, which leads to hyper-conductive system, which leads to hyper-polarisation and cause such effects to the heart polarisation and cause such effects to the heart activity:activity:

- Negative inotropic effect - decreasing strength - Negative inotropic effect - decreasing strength of heart contractions;of heart contractions;

- Negative chrono-tropic effect - decreasing - Negative chrono-tropic effect - decreasing heartbeat rate;heartbeat rate;

-Negative dromo-tropic effect - decreasing heart -Negative dromo-tropic effect - decreasing heart conductibility;conductibility;

- Negative bathmo-tropic effect - decreasing - Negative bathmo-tropic effect - decreasing excitability of heart muscle.excitability of heart muscle.

Location of receptors in the Location of receptors in the heartheart

Heart muscle contains, both Heart muscle contains, both chemical and stretch receptors chemical and stretch receptors in coronary vessels, all heart in coronary vessels, all heart cameras and pericardium. cameras and pericardium. Stretch receptors are irritated by Stretch receptors are irritated by changing blood pressure in heart changing blood pressure in heart cameras and vessels. cameras and vessels.

Chemo sensitive cells, which are Chemo sensitive cells, which are stimulated by decrease O2, stimulated by decrease O2, increase of CO2, H+ and increase of CO2, H+ and biological active substances biological active substances also, are called as also, are called as chemoreceptors. chemoreceptors.

Cardiovascular Adjustments Cardiovascular Adjustments to Exerciseto Exercise

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 Characteristic of afferent linklink

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 and hypothalamus in regulation of hypothalamus in regulation of

blood flowblood flowCenters 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

toneNeural 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 liver Uxta 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 Regulation of blood flow in blood flow in

physical physical exercisesexercises

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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