Physiology of heart. Physiological bases of hemo dynamic.

1. Physiology of heart. Physiological bases of hemo dynamic.

4. Automatism

5. Active potentialof contractiveheart cells

6. Phases of active potential • 0 – depolarization • 1 – beginning rapid repolarization • 2 – slowly repolarization or plateau • 3 – ending rapid repolarization • 4 – rest period.

7. Active potential, contraction, excitability of heart cells 4 – absolute refractivity; 5 – relative refractivity; 6 – period of increase excatability; 7 - exaltation

8. Conductive system of heart 2 – SA node; 3 – Bachman tract; 4 – tracts of Bachman, Venkebach, Torel 6 – AV node 7 – Hiss bungle 8 – right leg of Hiss bungle 9 – anterior brunch of left leg of Hiss bungle 10 – posterior brunch of left leg of Hiss bungle 11 - Kent bungle 12 – Jams bungle 13 - Meacham bungle

10. Cardiac cycle Systole • 1. period of tension • asynchrony contraction • isometric contraction • (all valves are closed) • 2. period of ejection • protosphigmic interval (opening of semilunear valves) • fast ejection • slow ejection

11. Cardiac cycle Diastole • 1. Period of relaxation • protodiastolic interval (closing of semilunear valves) • phase of isometric relaxation (opening of AV-valves is end of this phase) • 2. Period of filling • phase of rapid filling • phase of slow filling • phase of filling by help of atrium systole

12. Heart sounds. Components • I tone.1. Valve component (AV valves). • 2. Muscle component. • 3. Vessels component (opening of semilunear valves) • 4. Atrium component. • II tone. 1. Valve component (closing of semilunear valves) • 2. Vessels component.

14. Echocardiography • 1. M-measure • 2. D-measure • 3. Doppler • 4. Contrasting

23. Effects of thyroid hormones • Thyroid hormones increase transmission process in ribosome and nucleus of cells. Intracellular enzymes are stimulated due to increasing protein synthesis. Also increases glucose absorption and uptake of glucose by cells, increases glycolisis and gluconeogenesis. In blood plasma increases contents of free fatty acids. • All these effects of thyroid hormones lead to increase activity of mitochondria in heart cells and ATP formation in it. So, both activity of heart muscle and conduction of impulses are stimulated.

24. Effects of adrenocortical hormones • Aldosterone causes increasing Na+ and Cl- in blood and decreases K+. This is actually for producing action potential in the heart. Cortisol stimulates gluconeogenesis and increase blood glucose level. • Amino acids blood level and free fatty acids concentration in blood increases also. Utilization of free fatty acids for energy increases. These mechanisms actual in stress reaction. So heart activity is stimulated.

25. Hormones of Langerhans’ islets effects • Insulin promotes facilitated diffusion of glucose into cells by activation glucokinase that phosphorilates glucose and traps it in the cell, promotes glucose utilization, causes active transport of amino acids into cells, promote translation of mRNA in ribosome to form new proteins. Also insulin promotes glucose utilization in cardiac muscle, because of utilization fatty acids for energy. • Clucagone stimulate gluconeogenesis, mobilizes fatty acids from adipose tissue, promotes utilization free fatty acids foe energy and promotes gluconeogenesis from glycerol. So both hormones can increase strength of heartbeat.

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

27. Effects of nn. vagi • Effects of nn. vagus on the heart activity. Parasympathetic stimulation causes decrease in heart rate and contractility, causing blood flow to decrease. • It is known as negative inotropic, dromotropic, bathmotropic and chronotropic effect.

28. Effects of acetylcholine • Effects of acetylcholin leads to increase of K+ permeability through cell membrane in conductive system, which leads to hyper-polarisation and cause such effects to the heart activity: • - Negative inotropic effect - decreasing strength of heart contractions; • - Negative chrono-tropic effect - decreasing heartbeat rate; • -Negative dromo-tropic effect - decreasing heart conductibility; • - Negative bathmo-tropic effect - decreasing excitability of heart muscle.

30. Location of receptors in the heart • Heart muscle contains, both chemical and stretch receptors in coronary vessels, all heart cameras and pericardium. Stretch receptors are irritated by changing blood pressure in heart cameras and vessels. • Chemo sensitive cells, which are stimulated by decrease O2, increase of CO2, H+ and biological active substances also, are called as chemoreceptors.

33. Cardiovascular Adjustments to Exercise

34. Influencesof metabolic products on the diameter of vessels Increase of Н+ ions, pyroveniger and lactic acids, decrease of pO2 and increase ofpCO2in tissues Decrease of tone of precapillary sphincters Dilatation of arterioles Increaseof blood flowin organs

35. 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.

36. Role of mechano- and chemoreceptorin 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 mechanoreceptorsof carotid sinus zone lead by Sino carotid nerve(brunchof glossopharingeal nerve) to the medulla oblongata.

37. 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 ofchemical 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, maximalis 200 mm Hg. Increase of pressure higher than that level don’t lead to addition increase of impulsation.

38. 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.

39. Vasomotor center of medulla oblongatais 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 contractionand as result minute volume of blood flow. Regulatory influences of neurons of pressor zoneact by help ofincrease 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.

40. Role of brain cortexand 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 hypothalamiclevelgive 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 cortexalso give the descendent influenceson 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 influencesformas a resultof comparethe information, whichenter in higherpartof nervous systemfromdifferentreceptor zones. It supportrealizationof cardio-vascular component of emotions, reaction of behavior.

42. Nervousefferentlink of regulation of vascular tone Neural mechanism of efferent regulation of blood flowact by - Preganglionic sympathetic neurons, body of which present in the anterior root of thoracic and lumbar part of spinal cord andpostganglionic neurons, which are present in para-and prevertebral sympathetic ganglion. - Preganglionicparasympathetic neuronsof 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, cholinergicand other mechanism of regulation act on heart and vessels.

44. Peculiaritiesof influencesof catecholamineon the diameter of vessels Adrenal gland medulla Epinephrine Norepinephrine Action withα-adrenoreceptors of vessel wall Action withα-adrenoreceptors of vessel wall Action with β-adrenoreceptors of vessel wall Spasm of vessels of skeen, digestive organs, kidney and lungs Dilation of vessels Dilation of vessels of muscles, brain, heart

45. Influences of chatecholamines and vasopressin on the vessel tone • Influences of chatecholamines from adrenal glandsdetermined by presents of different kinds of adrenoreceptors– α and β. Connection of hormones withα–adrenoreceptorsactconstriction of vessel wall, with β–adrenoreceptor - relaxation. • Adrenalinconnect with α– and β–adrenoreceptor, nor epinephrinewith α–adrenoreceptor. Adrenalin hasstrong action on vessels. On artery and arterioles of skin, digestive organs, kidneys and lungsit has constrictive influences; on the vessels of skeletal muscles, brain and heart - dilatatory. On the physical load, emotional loadit increase blood flowthrough skeletal muscles, brain and heart. • Vasopressin (antidiuretichormone) causespasm of artery and arterioles of organs of abdominal cavity and lungs. But vessels of brain and heartreacted on that hormoneby dilatation, which help increase the nutrition of brain and heart.

46. Rennin–angiotensin-aldosteron system Cells of liver Uxta glomerular cell of kidney Angiotensinogen Rennin Angiotensin І Angiotensin converting enzyme Angiotensin ІІ Vascular spasm Angiotensin ІІІ Increase of arterialpressure Adrenal glands Reabsorbtion of water in kidneys Aldosteron Increaseof water in body

47. Roleof rennin–angiotensin-aldosteron systemin regulationof vessel tone Uxta glomerular cells of kidney produce enzyme rennin as the answer of decrease of kidneysperfusion or increase of influences of sympathetic nervous system. It convertangiotensinogen, which produced in liver, inAngiotensin І. AngiotensinІ, by the influences of angiotensin converting enzyme inthe vessel of lung, convertedinangiotensin II. AngiotensinІІhasstrongvasculoconstrictor influences. It can explain of presents of sensoryto angiotensinII receptorsinprecapillaryarterioles. Very big dose of angiotensinII can causethe spasmof vessels of heart and brain. Increase ofrenninand angiotensinin blood increase the thirst (need to drink water). AlsoangiotensinII orangiotensinIII, stimulate the production ofaldosteron. Aldosteron,which producein 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 therennin–angiotensin-aldosteron system.

48. Changesof blood flowin the clinostatic pose Change the body pose from vertical to horizontal Increase of blood flow to heart Increase the stroke volume Increaseof impulsation from mechanoreceptors of aortic arc Activation of depressor partof vasomotor center Inhibition of pressor partof vasomotor center Decreaseoffrequency and force of heart beat, dilation of vessels

49. Changesof blood flowin the orthostatic pose Change the body pose from horizontal to vertical Depo of blood in the vein of down part ofbody Decreaseof blood flow to heart Decrease of stroke volume Decreaseof impulsation from mechanoreceptors of aortic arc Activation of pressor partof vasomotor center Increaseoffrequency and force of heart beat, vascular spasm

50. 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.