Physiological Principles of the Cardiovascular System PDF

cardiac conductive system 1: - conductive system is important for synchronized contraction Poiseuille’s law: - pressure gradient is directly proportional with arterial blood flow Reflex mechanisms of the heart control: - the oculo-cardic reflex is mediated by trigeminal nerve bradycardio + cardiac c...

cardiac conductive system 1: - conductive system is important for synchronized contraction Poiseuille’s law: - pressure gradient is directly proportional with arterial blood flow Reflex mechanisms of the heart control: - the oculo-cardic reflex is mediated by trigeminal nerve bradycardio + cardiac conductive system 3: - the action potential In nodal cells depends on presence of leaking and voltage-gated channels cardiac conductive system 4: - conductive system is important for impulse formation cardiac cycle: - during isovolumetric relaxation all valves are closed cardiac electrophysiology and action potentials (AP) - phases of the AP are 0, 1, 2, 3, 4 cardiac electrophysiology and action potentials (AP) 2: - resting membrane potential is in myocardial working cells -85 to -90 mV cardiac volumes at rest (in healthy 70-kilogram man) - the systolic (stroke) volume is about 70mL mechanical manifestation of cardiac activity: - we can usually hear 2 cardiac sounds by auscultation myocardial contraction: - action potential causes calcium influx from extracellular fluid to sarcomeres phases of the action potential (AP) of the myocardial cells 2: - the phase 2 is important for duration of action potential phases of the action potential (AP) of the myocardial cells 4: - the slow diastolic depolarization can be present in the phase 4 phases of the action potential (AP) of the myocardial cells 5: - the fast K channel is active in the phase 3 phase of the action potential (AP) of the myocardial cells: - the phase 0 is a period of depolarization phase of the action potential of the myocardial cells 3: - the phase 3 is a repolarization Venous haemodynamics: - arterial pulsations increase the venous blood flow reflex mechanisms for maintaining normal blood pressure: - receptors in atrias and pulmonary arteries elicit reflexes parallel to the baroreceptor reflexes reflex mechanisms of the heart control: - receptors for Bainbridge reflex are stretch receptors in atrias the vasomotor center: - the sensory area neurons in the nucleus tractus solitarii receive signal mainly through the vagus and glossopharyngeal nerves the gradient of cardiac automaticity: - cardiac automaticity is the highest in the sinus (SA) node True statement: - norepinephrine binds to adrenergic receptors Autoregulation of blood flow: - rapid increase in arterial pressure causes immediate increase in blood flow and fast flow decrease to the normal level Acute control of local blood flow: - vasodilator substance from the tissue cells are released according to the less availability of oxygen Basic physiological properties of the myocardium are: - contraction of the cardiac muscle (contractility) = haemodynamic function Blood reservoirs: - Venous system serves as a blood reservoir for the circulation Blood pressure (BP) - normal blood pressure for healthy adults is 120/80 mm Hg (systolic/diastolic Capillaries: - structure of the capillary wall: layer of endothelial cells, thin basement membrane ECG evaluation 3: - normal cardiac electric axis is from -30 degree to +105 degree ECG evaluation 5: - the T wave is typically negative in lead aVR in healthy people Effect of oxygen lack on arterial pressure: - signals from carotid and aortic chemoreceptors excite the vasomotor center, and this elevates the arterial pressure back toward normal Effects of hormones and electrolytes on the heart: - high blood potassium levels decrease myocardial contractility Effects of hormones on the heart: - norepinephrine increases myocardial contractility Antidiuretic hormone: - Antidiuretic hormone ADH increases blood volume Mechanical manifestations of cardiac activity: - 1st cardiac sound is the result of atrioventricular valve closure myocardial contraction: - action potential causes calcium influx from sarcoplasmic reticulum to sarcomeres phases of the action potential (AP) of the myocardial cells 2: - the ap voltage during phase 2 is near zero value phases of the action potential (AP) of the myocardial cells 4: - The slow diastolic depolarization can be present in the pase 4 phases of the action potential (AP) of the myocardial cells 5: - The AP value in the phase 4 is changing in the nodal cells poiseuille’s law - increased blood viscosity decreases the arterial blood flow reflex mechanisms for maintaining normal blood pressure: - receptors in arteries and pulmonary arteries ellcit reflexes parallel to the baroreceptors reflexes haemodynamics in capillaries: - the blood flow in capillaries is slower than in arteries ECG evaluation 3: - normal cardiac electric axis is from -30 degrees to +105 degree ECG evaluation 5: - the t wave is typically negative in lead aVR in healthy people effect on oxygen lack on arterial pressure: - signals from carotid and aortic chemoreceptors excite the vasomotor center, and this elevates the arterial pressure back towards normal effects of hormones and electrolytes on the heart: - high blood potassium levels decrease myocardial contractility effects of hormones on the heart: - norepinephrine increases myocardial contractility extracardiac nervous mechanisms of the heart control: - stimulation of the carotid sinus baroreceptors (baroreflex) results in bradycardia and hypotension flow in blood vessels: - the flow may become turbulent when the rate of blood flow becomes too great foetal haemodynamics - pulmonary artery is connected with the aorta by ductus arteriosus haemodynamics in capillaries - plasma coloid osmotic pressure (oncotic pressure) prevents significant loss of fluid volume from the blood haemodynamics in capillaries - the blood flow in capillaries is slower than in arteries cardiac conductive system 1 - conductive system is important for synchronized contraction cardiac conductive system 3 - the slowest cardiac conduction is in the AV node cardiac conductive system 4 - gradient of automaticity decreases in the order SA node, AV node, purkinje cells ECG evaluation 1 - standard ecg recording consists of 12 leads ecg evaluation 3 - normal cardiac electric axis is from -30 to +105 ecg evaluation 5 - the t wave is typically negative in lead aVR in healthy people effect of oxygen lack on arterial pressure - signals from carotid and aortic chemoreceptors excite the vasomotor center, and this elevates the arterial pressure toward normal cardiac conductive system 4 - gradient of automaticity decreases in the order SA node, AV node, purkinje cells cardiac cycle: - during ejection phase, semilunar valves are open cardiac electrophysiology and action potentials (AP) - the amplitude of cardiac action potentials is approximately 100 mV cardiac electrophysiology and action potentials (AP) 2 - resting membrane potential is the result of the concentration and electrical gradient cardiac volumes at rest (in healthy 70-kilogram man) - the end diastolic volume is the largest cardiac volume extracardiac nervous mechanism of the heart control: - glossopharyngeal nerve carries impulses from carotid sinus baroreceptors Flow in blood vessels: - turbulent flow is blood flowing in all directions in the vessel foetal haemodynamics: - oxygenated blood to the foetus comes from the placenta for increase of arterial blood pressure is important: - an increase of total peripheral resistance by contraction of arterioles haemodynamics in capillaries: - blood flow in capillaries is slower than in arteries the gradient of cardiac automaticity - cardiac automaticity is the highest in the sinus (SA) node True statement: - Norepinephrine binds to adrenergic receptors autoregulation of blood flow - rapid increase in arterial pressure causes immediate increase in blood flow and fast flow decreases to the normal level acute control of local blood flow - vasodilator substances from the tissue cells are released according to the less availability of oxygen basic physiological properties of the myocardium are: - contraction of the cardiac muscle (contractility)= haemodynamic function blood reservoir - venous system serves as a blood reservoir for the circulation bloodpressure (BP) - normal blood pressure for healthy adult is 120/80 mm Hg (systolic/diastolic) capillaries: - structure of the capillary wall: layer of endothelial cells, thin basement membrane Reflex mechanisms for maintaining normal blood pressure: receptors in atrias and pulmonary arteries elicit reflexes parallel to the baroreceptor reflexes reflex mechanisms of the heart control: - receptors for bainbridge reflex are the stretch receptors in atrias reflexes acting on the heart - the oculo-cardiac reflex is mediated by trigeminal nerve the vasomotor center - the sensory area neurons in the nucleus tractus solitarii receive signal mainly through the vagus and glossopharyngeal nerves The gradient of cardiac automaticity - cardiac automaticity is the highest in the sinus (SA) node true statement: - norepinephrine binds to adrenergic receptors autoregulation of blood flow: - rapid increase in arterial pressure causes immediate increase in blood flow and fast flow decrease to the normal level acute control of local blood flow - vasodilator substances from the tissue cells are released according to the less availability of oxygen mechanical manifestations of cardiac activity - we can usually hear 2 cardiac sounds by auscultation myocardial contraction: - action potential causes calcium influx from extracellular fluid to sarcomeres phases of the action potential (AP) of the myocardial cells 2 - The phase 2 is important for duration of action potential Phases of the action potential (AP) of the myocardial cells 4: - the slow diastolic depolarization can be present in the phase 4 phases of the action potential (AP) of the myocardial cells 5: - the fast k channel is active in the phase 3 phases of the action potential (AP) of the myocardial cells: - the phase 0 is a period of depolarization phases of the action potential of the myocardial cells 3 - the phase 3 is a repolarization control of blood volume - antidiuretic hormone major function is to increase greatly water reabsorption ECG evaluation 1 - Normal duration of the QRS complex is under 0.11 s ECG evaluation 3 - normal heart rate is 60-100/min ECG evaluation 5 - The t wave is typically negative in lead aVR in healthy people effect of oxygen lack on arterial pressure - signals from carotid and aortic chemoreceptors excite the vasomotor center, and this elevated the arterial pressure back towards normal effects of hormones and electrolytes on the heart - high blood potassium levels decreases myocardial contractility effects of hormones of the heart: - epinephrine increases heart rate? extracardiac nervous mechanism of the heart control - inspirium increases the sympathetic activity on the heart poiseuille’s law - increased blood viscosity decreases the arterial blood flow reflex mechanism for maintaining normal blood pressure: - receptors in atrias and pulmonary arteries elicit reflexes parallel to the baroreceptor reflexes reflex mechanism of the heart control: - bainbridge reflex helps to prevent damming of blood in the veins, atria and pulmonary circulation reflexes acting on the heart 2: - peripheral chemoreceptors are situated in the carotic body the vasomotor center: - a vasoconstrictor area is located bilaterally in the upper medulla the gradient of cardiac automaticity: - the leading pacemaker is the structure with the highest automaticity true statement - norepinephrine binds to adrenergic receptors control of blood volume: - antidiuretic hormone major function is to increase greatly water reabsorption electrical manifestations of cardiac activity (ECG) - electrocardiodiagram is recorded in 12 leads normally electrocardiography (ECG) - PQ interval represents the time the impulse takes to reach the ventricles from the sinus node excitability of the heart 1: - during relative refractory period a very strong stimulus can initiate action potential extracardial hormonal mechanism - thyreoid hormones produce tachycardia extracardiac mechanism of the heart control - acetylcholine has a negative chronotropic effect extracardiac nervous mechanism of the heart control 1: - extracardiac nerves are important for the heart control extracardiac nervous mechanism of the heart control: - inspirium increases the sympathetic activity on the heart Foetal haemodynamics: - pulmonary artery is connected with the aorta by ductus arteriosus humoral control of the circulation - bradykinin causes arteriolar dilation and increased capillary permeability long term control of circulation: - angiotensin 2 causes the increase of secretion of aldosteron from adrenal glands extracardiac humoral mechanism of the heart control: - thyreoid hormones act similarly to epinephrine - thyreoid hormones produce tachycardia extracardiac mechanism of the heart control: - acetylcholine has a negative chronotropic effect extracardiac nervous mechanism of the heart control 1: - the cardioinhibitory center produces bradycardia extracardiac nervous mechanism of the heart control - inspirium increases the sympathetic activity on the heart cardiac conductive system 4 - gradient of automaticity decreases in the order sa node, av node, purkinje cells extracardiac nervous mechanisms of the heart control: - stimulation of the carotid sinus baroreceptors (baroreflex) results in bradycardia and hypertension flow in blood vessels: - the flow may become turbulent when the rate of blood flow becomes to great humoral control of the circulatation: - bradykinin causes arteriolar dilation and increased capillary permeability long term control of the circulation: - angiotensin 2 causes the increase of secretion of aldosteron from adrenal glands electrocardiography (ECG) - the leads aVR, aVL, aVF are unipolar excitability of the heart 1 - During relative refractory period a very strong stimulus can initiate action potential phases of the action potential (AP) of the myocardial cells: - the AP in the phase 0 is negative and also positive Phases of action potential of the myocardial cells 3: - the phase 3 is influenced by activity of outward K channel basic physiological properties of the myocardium are: - conduction of stimuli through myocardium (conductivity) blood reservoirs: - venous system serves as a blood reservoir for the circulation Bloodpressure: - BP is usually measured with sphygmomanometer Capillaries: - lipid soluble substances can be diffuse directly through the cell membranes Acute control of local blood: - vasodilator substances from the tissue cells are released according to an increase of the rate of the metabolism Autoregulation of blood flow: - rapid increase in arterial pressure causes immediate increase in blood flow and fast flow decrease to the normal level Sound of a cuspid valve closing: - Lubb Sound of a semilunar valve closing: - Dubb Sound of aortic semilunar valve are heard: - 2nd intercostal space at right sternal margin Sound of pulmonary semilunar valve are heard in: - 2nd intercostal space at left sternal margin Sound of mitral valve are heard: - over apex - In 5th intercostal space - in line with middle of clavicle Sound of tricuspid valve are heard: - In right sternal margin of 5th intercostal space - variations: Over sternum or over left sternal margin in 5th intercostal space Preload factors: (end diastolic volume) - Venous return - fluid volume - atrial contraction Preload happens during: (end diastolic volume) - Diastole Preload is: - Volume entering the ventricles Afterload happens during: - systole Afterload is: - Resistance ventricles must overcome to circulate blood Factors increasing afterload: - atherosclerosis - vasoconstriction Contractility is: - How hard the myocardium contracts for a given preload Influence contractility: - iontropic factors Positive iontropes: - Increase contractility - Sympathetic stimulation - noradrenaline Negative iontropes: - Decrease contractility - parasympatetic - acetylcholine - beta blockers The absolute refractory phase is measured: Method of extra stimulation Means of 2 impulses (S1+S2) Means of increasing frequency of impulses The vulnerable period has: The inner (earliest) limit The outer (latest) limit The absolute refractory phase is measured: Method of extra stimulation Means of 2 impulses (S1+S2) Means of increasing frequency of impulses The vulnerable period has: The inner (earliest) limit The outer (latest) limit The vulnerable period of the heart correlates with: Absolute refractory period Supranormal period/phase The oxygen consumption in the heart: Is larger than in other cells The oxygen consumption is increased during: Pressure work Tachycardia Decreased blood pressure Which reflex is acting on the vascular tone: Sinocarotid Gauer-Herny During supranormal phase the excitability threshold is: Decreased The slow diastolic depolarization correlates with: Phase 4 of action potential The site of transmission of excitation between two cardiac cells is: The conduction system Bundle of His Purkinje cells (non credo) The vectorcardiographic horizontal plane is formed from: Leads X and Z The vectorcardiographic frontal plane is formed from: Leads X and Y The vectorcardiographic sagital plane is formed from: Leads Z and Y The relative refractory period correlates with: Phase 3 of action potential Abundance of Ca2+ions: Calcium rigor All cardiac valves are close during: Strain isovolumic phase (isometric ventricular contraction) Isovolumic relaxation (isometric relaxation) Phases 0,1,2,3,4 of the cardiac action potential are present in: Working myocardium Purkinje cells Peculiarities of venous hemodynamics: Large distensibility of vessels Presence of venous valves in legs Influence of breathing Influence of muscle activity Peculiariteis of the lung hemodynamics: Small pressure gradient Stop of the flow in diastole Pulsative blood flow in capillaries Oxygen debt occurs in: Skeletal muscle’ Only slow Na-Ca inward channels are presented in: The sinus node AV node Pacemaker’s cells Tachycardia is produced by: Orthostatic rest Action of hormones and electrolytes on the heart: -abundance of calcium produces cardiac rigor -abundance of acetylcholine produces bradycardia Basic Physiological properties of the myocardium are: -rhythmic formation of impulses (rhythmicity) 60-80 per minute -conduction of stimuli through the myocardium (conductivity) - automatic formation of impulse (automaticity) with some heart rate -contraction of the cardiac muscle (contractility)-hemodynamic function -Sodium and potassium channels Blood pressure (BP) values: -the upper limit of normal BP values is 145/85 mmHg (19.3/11.3kPa) -mean BP is the diastolic value plus 1/3 of pressure amplitude -normal BP for young adults is 90-120/60-80 mmHg Cardiac activity (ECG) -for evaluation of wave amplitude we the need the paper speed Cardiac conductive system 1: -the sinoatrial node is the normal pacemaker -is morphologically and functionally heterogenous -Purkinje cells have the fastest conduction impulse -transient cells are very sensitive to some changes -​conductive system is important for synchronized contraction -the action potential in nodal cells depends on presence of leaking and voltage – gated channels Cardiac conductive system 2: -the action potential in nodal cells is produces by slow channels -the amplitude of action potentials in nodal cells is very steep -the speed of conductivity in whole conductive system is very high -the slowest cardiac conduction is in the SA node -Purkinje cells are the largest cardiac cells -conductive system is important for synchronized contraction Cardiac conductive system 3 -gradient of automaticity increase in the order SA node, AV node, Purkinje cells -conductive system is important for connection of the atria to the ventricles -conductive system is important for impulse formation -cardiac automaticity is demonstrated by Stannius liguature Cardiac electrophysiology and action potentials (AP): -the amplitude of cardiac action potentials is approximately 100mV -phases of the AP are 0,1,2,3,4 -rapid depolarization is produced by opening the sodium channels -the phase plateau produces prolongetion of the AP compared to the nervous cells -During depolarization the sodium channels are opened Cardiac nervous mechanisms of the heart 2: -the vagus nerve has a negative chronotropic effect -the sympathetic nerves have a positive bathmotropic effect -the sympathetic nerves have a positive dromotropic effect -the sympathetic nerves have a positive chronotropic effect -the sympathetic nerves have a positive inotropic effect Cardiac work: -the heart works without oxygen debt -oxygen consumption is increased by tachycardia -oxygen consumption is measured indirectly -oxygen consumption is increased in pressure work Normal cardiac output in rest (healthy 70kg man) is 4.0 – 6.0 L / minute Cerebral hemodynamics: -Cushing reflex is produced by ischemia in the brain -brain autoregulation is constant blood pressure during changed flow -Monroe-Kellie doctrine is valid for the brain hemodynamics -brain autoregulation is constant blood flow during gravitation Contractility and cardiac cycle: -in the strain phase all valves are closed -the filling phase consists of fast and slow filling -in the isovolumic relaxation the ventricular blood pressure is 0mmHg/125mmHg ??? Control of cardiac activity 1: -Starling`s law of the heart is dependence of power on ventricularfibre length -Woodworst steps are decreased in the contraction force by bradycardia/tachycardia (?) -the Anrep mechanism is dependent on the aortic blood pressure -Bowditch steps are increased in the contraction force by tachycardia Coronary hemodynamics​: -capillaries are very numerous, all capillaries open at rest -most of blood flow is in diastole -tachycardia decreases coronary blood flow -stop the flow in systole -For evaluation of wave amplitude we need the paper speed Electrical manifestation of cardiac activity 2: -vectorcardiogram is a record of cardiac electric field -precordial mapping is record of depolarization and repolarization potentials -magnetocardiography is recording the cardiac magnetic field -vectorcardiogram is recorded as loops in 3 planes -heart rate variability is measurement of PQ intervals -magnetocardiography is recording by magnets Evaluation of ECG: -normal QRS complex duration is < 110 ms Excitability of the heart: -the excitability threshold is proportional to excitability -during relative refractory period the excitability is decrease -during absolutely reflectory period the excitability is very decreased -the excitability freshold is in the opposite relation to excitability -During absolute refractory period the cells are not excitable Excitation-contraction coupling in the myocardium: -actin and myosin are contractile proteins - troponine and tropomyosin are contractile proteins Extracardiac humoral mechanisms of the heart control: -adenosine produces bradycardia -thyroid hormones produce tachycardia Extracardiac nervous mechanisms of the heart control 1: -the parasympathetic nerves are prevailing at rest -the parasympathetic postganglionic neurotransmitter is acetylcholine Extracardiac nervous mechanisms of the heart control 3: -the cardiomotor center produces tachycardia/ bradycardia -cardiac activity is influenced by cerebellum, labyrinth and limbic system -extracardiac nerves are most important for the heart control -the respiratory center produces tachycardia and bradycardia -the sympathetic nerves activate alpha- and beta-receptors -the sympathetic nerves activate input of Na+ and Ca 2+ ions into cardiomyocytes Extracardiac nervous mechanisms of the heart control 4: -the parasympathetic nerves activate M- and N-cholinoreceptors -the parasympathetic nerves activate input of K+ ions into cardiomyocytes -the parasympathetic nerves stimulate hyperpolarization in cardiomyocytes -the parasympathetic nerves stimulate negative chrono-, dromo-, ino-, bathmotropic effects Extracardiac nervous mechanisms of the heart control 6: -the hypothalamus produces coordination od autonomic reactions with cardiac activity -the brain cortex realizes psychic influences in cardiac activity -the hypothalamus produces tachycardia during autonomic reactions -the limbic system produces bradycardia during autonomic reactions -the brain cortex produces tachycardia -the brain cortex produce bradycardia Extracardiac nervous mechanisms of the heart control 7: -baroreceptors in the carotic sinus have sensitive innervation by the glossophyryngeal nerve -stimulation of the carotic sinus baroreceptors (baroreflex) produces bradycardia and hypotension -stimulation of the oculo-cardiac reflex produces bradycardia -stimulation of the naso-cardiac reflex produces bradycardia -baroreceptors of the aortic arch have sensitive innervation by the depressor nerve -stimulation of the carotic sinus baroreceptors (baroreflex) produces bradycardia and hypotension Extracardiac nervous mechanisms of the heart control 8: -reflex of Bainbridge is eliceted by increased venous return -reflex of bainbridge produces tachycardia -reflex of Gauer-Henry is elicited by decrease in atrial blood volume -reflex of Gauer-Henry produces decrease in hypothalamic ADH secretion Extracardiac nervous mechanisms of the heart control 9: -peripheral arterial chemoreceptors are situated in the carotic sinus -peripheral arterial chemoreceptors are situated in the aortic arch -the Bezold-Jarisch-Hirt reflex produces bradycardia, hypotension and apnoe -stimulation of peripheral arterial chemoreceptors produces the Bezold-Jarisch-Hirt reflex Fetal hemodynamics 1: -is formed by one umbilical vein and two arteries -the most oxygenated blood comes to the brain of fetus -oxygenated blood comes from placenta -oxygenated blood to the fetus comes via 2 umbilical arteries ? -oxygenated and deoxygenated blood is mixed in the fetus ? -the most oxygenated blood is in the umbilical vein -the highest blood pressure is in the umbilical artery -the blood pressure in the umbilical artery is higher than in the umbilical vein Pulmonary artery is connected with the aorta by ductus arteriosus Fetal hemodynamics 2: -the least oxygenated blood remains in fetus -the arterial duct is closed after birth -the venous duct is closed after birth -the venous and arterial ducts are shunts -pulmonary artery blood pressure is higher than aortic one Hemodynamics in arteries 1: -increased length of the artery decreases the arterial blood flow -increased blood viscosity decreases the arterial blood flow -law of Poiseuille-Hagen deals with the arterial blood flow and pressure -increased pressure gradient increases the arterial blood flow Hemodynamics in capillaries: -deformability of erythrocytes is present in narrow capillaries -the blood flow is very slow there -blood flow in capillaries is slower than in arteries/veins -oncotic pressure is important for water reabsorption -distensibility and low blood pressure are typical for capillaries Hemodynamics in the skin: -main regulator are neurohumoral influences Hemodynamics in the skeletal muscles: -intermittent blood flow is present between contracts only -a few capillaries are open at rest -its metabolism during exercise is anaerobic -skeletal muscles produce hand-grip test Mechanical manifestations of cardiac activity: -apexcardiogram is a part of cardiac polygraphy -sphygmogram is a part of cardiac polygraphy -we can usually hear 2 cardiac sounds by auscultation -2​nd​ cardiac sound is the result of semilunar valves closure (Pulmonary and aortic are semilunar valves) Pulmonary hemodynamics: -pressure gradient is very low there -stop of blood flow in diastole -not important for nutrition -numerous ateriolo-venular shunts present Reflexes acting on the heart 1: -activation of baroreceptors produces bradycardia -hand-grip test produces tachycardia -adrenergic alpha-receptors increase the contraction force -the oculo-cardiac reflex produce bradycardia -the oculo-cardiac reflex is mediated by trigeminal nerve -the naso-cardiac reflex produce bradycardia Reflexes acting on the heart 2: -crease ADH (hormone) secretion in hypothalamus -central chemoreceptors are situated in medulla oblongata -signals transmitted from the chemoreceptors excite the vasomotor center -reflex of Bainbridge produces normally tachycardia -peripheral chemoreceptors are situated in the carotid body -central chemoreceptors are situated in the heart -the gauter-henry reflex D Reflexes acting on the heart 3: -cardiac chemoreceptors are situated in both ventricles -the carotic sinus reflex is stimulated by decrease in blood pressure Splanchnic hemodynamics: -autoregulation means increased flow after meal -the hepatic sinusoids are low permeable -the hepatic sinusoids are high permeable for proteins Venous hemodynamics: -negative intrathoracic pressure supports it -arterial pulsations increase the venous blood flow -veins are very distensible -lower extremity movements increase blood return to the heart -veins are more distensibile than arteries Vasodilation is produced by: EDRF 2. Nitrogen oxide (NO) General vasodilation is produced by: Parasympathetic nerves always Decrease in sympathetic tone Negative deflection in ECG arises: When the impulse go from the electrode away in unipolar leads Intracardiac control mechanisms are: Heterometric (Frank-Starling) Homeometric (Anrep) Decrease of the blood pressure is realized by stimulating: Carotid body Carotid sinus Aortic arch Nervous vasomotor mechanisms: Generalised vasoconstriction is produced via sympathethic adrenergic Active vasodilation is produced via parasympathethic cholinergic fibres Passive vasodilation is produced by the decrease sympathethic activity Generalised vasodilation is produced via the parasympathethic nerves Blood volume control is realized by: Atrial natriuretic peptide (ANP) Gauer-Herny diuretic reflex Osmoreceptors in hypothalamus Juxtaglomerular apparatus in kidneys Bradycardia and vasodilation are produced by: Sinocarotid reflex Bezold-Jarisch reflex Stimulation of aortic baroreceptors Bradycardia is produced by: Sinocarotid reflex Gold reflex Nervous control of the blood pressure (BP): -the Bezold-Jarish-Hirt reflex produces bradycardia, hypotension & hypopnea -baroreflexes produce vasoconstriction and tachycardia -stimulated vasopressoric part of the vasomotor center increases BP -stimulated vasodepressoric part of the vasomotor center decreases BP -a basal vasoconstrictor tone is present at rest (?) -reticular formation of the midbrain produces vasoconstriction (se non trovo niente, vasodilation) -the vestibular nuclei activate the sympathetic effects on the BP (blood pressure) (se non trovo niente, vagal effects) -the hypothalamus cortex activates vasomotor reactions during autonomic activity -the cerebral cortex activates vasomotor reactions during movements The vasomotor center: Vasoconstrictor area is located bilaterally in the upper medulla The sensory area neurons in the nucleus tractus solitarii receive signal mainly through the vagus nerve and glossopharyngeal True statements: Epinephrine binds to specific adrenergic receptors Norepinephrine binds to adrenergic receptors The gradient of cardiac automaticity: The leading pacemaker is the structure with highest automaticity Cardiac automaticity is the highest in the sinus (SA) node Cardiac automaticity increase from Purkinje fibers to SA node Flow of blood vessels: Turbulent flow is blood flowing in all directions in the vessels Long term control of circulation: Increased extracellular fluid volume trough increased cardiac output increases arterial pressure Excess salt in extracellular fluid increases the osmolality of the fluid, what inhibits the thirst center Angiotensin II causes the increase of secretion of aldosteron from adrenal glands Humoral control of the circulation: Bradyknin causes arterioles dilatation and increased capillary permeability An increase of calcium ions concentration causes vasodilation Vasopressin increase the total peripheral resistance Norepinephrine, angiotensin II and vasopressin are powerfull vasoconstrictor The major function of angiotensin II is increase water reabsorption Reflex mechanisms for maintaining normal blood pressure: Receptors in atrias and pulmonary arteries elicit reflexs parallel to the baroreceptors reflexes Signals from the “aortic baroreceptors” are transmitted through the herings nerve to the glossophyringeal nerves Bainbridge reflex is reflex increase of heart rate and strenght contraction Receptors in atrias and pulmonary arteries elicit reflexes parallel to the baroreceptors reflexes Stretch of the atria causes reflex dilatation of the afferent arterioles in the kidneys Reflex mechanisms of heart control: Bainbridge reflex helps to prevent damming in the veins, atria and pulmonary circulation Receptors for Bainbridge reflex are the stretch receptors in atrias Bainbridge reflex causes heart rate increase Control of blood volume: Antidiuretic hormone major function is to increase greatly H20 .. Autoregulation of blood flow: Rapid increase in arterial pressure causes immediate increase in blood flow and fast flow decrease to normal level Metabolic theory and myogenic theory have been proposed to explain acute autoregulation mechanism Acute blood flow control in specific tissues: Level of excitability of the brain is not dependent on control of concentration of carbon dioxide and hydrogen ions Acute control of local blood flow Vasodilator substances from the tissue cells are released according to the less the availability of oxygen Vasodilator substances from the tissue cells are released according to an increase of the rate of the metabolism Vasodilator substances are adenosine, carbon dioxide, histamine, postassium ions and hydrogens ions Basic physiological properties of myocardium are Acceptation of stimulti and reaction to them (excitability) Conduction of stimuli through myocardium (conductivity) Rhythmic formation of impulses (rhythmicity) 70-80 per minute Blood reservoirs 60 % of all the blood in the circulatory system is in the veins Venous system serves as a blood reservoirs for the circulation Specific blood reservoirs are spleen, skin, abdominal veins Blood pressure (BP): Mean arterial pressure is determined by about 60% of the diastolic pressure and about 40% of the systolic pressure Normal blood pressure for healty adult is 120/80mmHg (systolic/diastolic) Capillaries: Structure of the capillary wall layer of endothelial cells, thin basement membrane The capillary pressure tends to force fluid outward through capillary membrane Cardiac conductive system The sinoatrial node is the normal pacemaker Cardiac conductive system 3: The slowest cardiac conduction is in AV node Amplitude of action potential in nodal cells is very steep Cardiac conductive system 4 Conductive system is important for connection the atria to the ventricles Conductive system is important for synchronized contraction Conductive system is important for impulse formation Gradient of automaticity decrease in the order SA node, AV node, Purkinje cells Cardiac cycle During ejection phase semilunar valves are open During isovolumetric relaxation all valves are closed Ejection consist of fast and slow ejection Cardiac electrophysiology and action potentials (AP) During depolarization the sodium (Na) channels are opened During depolarization the potassium (K) channels are closed Phases of AP are 0,1,2,3,4 Cardiac electrophysiology and action potentials (AP) 2 Resting membrane potential is in myocardial working cells -85 to -90mV The phase Plateau produces prolongation of the AP compared to the nervous cells Resting membrane potential is a result of the concentration and electrical gradient Cardiac volumes at rest (in healthy 70-kilogram man) The ejection fraction is normally 60% The systolic (stroke) volume is about 70ml -the end diastolic volume is the largest cardiac volume -the end systolic volume is the smallest cardiac volume -the cardiac index is cardiac output per 1m2 of the body surface -the end diastolic volume is the largest cardiac volume Cardiac work Normal cardiac output in rest (healthy 70kg man) is 4.0 – 6.0 L / minute The source of energy for the heart are especially fatty acids Source of energy from glucose and glycerol ECG evaluation 1 Normal duration of the QRS complex is under 0.11 seconds Standard ECG recording consists of 12 leads Normal duration of the PQ interval is under 0.2 ECG evaluation 3 Normal heart rate is 60 – 100 / minute Normal cardiac electric axis is from -30 to +105 Normal cardiac electric axis is orientated to the right downward, forward ECG evaluation 5 The T wave is typically negative in lead aVR in healthy people The QRS complex is typically negative in lead aVR in healty people Position of the transition zone is most frequent situated between leads V3 and V4 The effect of oxygen lack on arterial pressure Carotid and aortic chemoreceptors become stimulated when the arterial pressure is slightly changed Signals from carotid and aortic chemoreceptors excite the vasomotor center and this elevates the arterial pressure (?) Effects of hormones and electrolytes on the heart High blood potassium (K) levels decrease myocardial contractility Lower blood calcium (Ca) levels decrease myocardial contractility Effects of hormones on the heart Norepinephrine increases myocardial contractility Epinephrine increase heart rate Thyroxine increase heart rate Epinephrine increase myocardial contractility Electrical manifestation of cardiac activity (ECG) For evaluation of wave amplitude we need the paper speed (sì ma..?) Electrocardiogram is recorded in 12 leads normally (for sure comparema) Electric axis of the heart is evaluated by Eindoven’s triangle Electrocardiography (ECG) QT interval duration is dependent on the heart rate PQ interval represent the time the impulse takes to .. the ventricles from sinus node The leads I, II, III are bipolar -ECG is recorded in standard 12 leads -the chest leads V1-V6 are unipolar -ECG is a summary body surface potential with amplitude of 1 Mv -the atrial myocytes are in phase 2 of action potential (or Plateau) during ST segment Excitability of the heart 1 During absolute refractory period the cells are not excitable During relative refractory period a very strong stimulus can initiate action potential Extracardiac humoral mechanisms of the heart control Thyroid hormones produce tachycardia Acetylcholine has a negative chronotropic effect Thyroid hormones acts similary to epinephrine Norepinephrine produces increase in the contraction force Cardioacceleratory center produces tachycardia Extracardiac mechanism of the heart control Norepinephrine has a positive chronotropic effect Norepinephrine has a positive ionotropic effect Extracardiac nervous mechanisms of the heart control 1 Cardiac activity is influenced by hypothalamus Cardioinhibitory center produces bradycardia Extra cardiac nerves are important for the heart control Glossopharyngeal nerve carries impulses from carotid sinus baroreceptors Sympathetic nerves activate input of Na+ and Ca2+ ions from cardiomyocytes Sympathetic nerves stimulate depolarization in cardiomyocytes Extracardiac nervous mechanisms of the heart control 2 Inspirium increases the sympathetic activity on the heart Inspirium procudes tachycardia The respiratory center influences the cardiac activity Extracardiac nervous mechanisms of the heart control 3 Parasympathetic nerves inhibit hyperpolarization in cardiomyocytes Extracardiac nervous mechanisms of the heart control Acetylcholine has a negative chronotropic effect Sympatethic nerves have a positive chronotropic effect Sympathetic nerves have a positive inotropic effect Vagus nerve carries impulses from aortic arch baroreceptors Flow in blood vessels Laminar flow means flow in streamlines and velocity of flow in the center of the vessel is far greater Turbulent flow is blood flowing in all directions in the vessel Flow may become turbulent when the rate of blood flow becomes too great Fetal hemodynamics Oxygenated blood to the fetus comes from the placenta Pulmonary artery is connected with aorta by ductus arteriosus After birth the ductus arteriosus becomes occluded For increase of arterial blood pressure is important An increase of total peripheral resistance by contraction of arterioles Hemodynamics in capillaries Deformability of erythrocytes is present in the narrow capillaries Plasma colloid osmotic pressure (oncotic pressure) prevents signification loss of fluid volume Blood flow in capillaries is slower than in arteries After birth the arotic pressure arises Myocardial contraction Troponin binds calcium ions AP causes potassium influx from sarcoplasmic reticulum to sarcomeres Phases of the action potential (AP) of the myocardial cells 2: The AP voltage during phase 2 is near zero value Phases of the action potential of the myocardial cells 4: The slow diastolic depolarization can be present in the phase 4 The AP value in the phase 4 is not chaning substantially in the working myocardium Phases of the action potential (AP) of the myocardial cells 5: The action potential value in phase 4 is changing in the nodal cells The AP within the phase 1 is positive Phases of the action potential (AP) of the myocardial cells The phase 0 is a period depolarization The phase 2 is important for duration of action potential The phase 3 is a period of repolarization The phase 1 is not present in all cardiac cell Phases of the action potential of the myocardial cells 3: The phase 3 is influenced by activity of outward Na channel Phases of the action potential (AP) of the myocardial cells: The phase 1 is repolarization The phase 4 is a period of diastole The fast Na channel is active in phase 0 The fast Na-Ca channel is active in phase 2 The fast K channel is active in the phase 3 The AP value in the phase 4 is chainging in the nodal cells FAST NA 3 – FAST NA 2 – FAST K 0 NO 100%! Poiseuille’s law Increased blood viscosity, decrease the arterial blood flow (+blood viscosity-arterial flow) Pressure gradient is directly proportional with the arterial flow (+pressure gradient+arterial flow) The factors promoting venous return: Work of the muscle pump Physiological value of ST segment on ECG is: +- 1mm at calibration 1mv=1mm Pulsative blood flow is typical for the: Lungs Veins Pulsative blood flow in capillaries is typical for the: Lungs Veins Arrhythmia on the ECG is always: An irregular rhytm Produced by respiration or by vagal tone Physiological – respiratory or sinus one Peculiarities of cardiac muscle: Cellular structure Long refractory period Different energy sources Nontitanic contraction Peculiarities of hemodynamics in the skin: Influence of temperature on blood flow Participation of Ay (av) shunts in hemodynamics Influence of axon reflexes Peculiarities of cerebral hemoydnamics: Monroe-Kelly principle Important nervous control Peculiarities of pulmonary hemodynamics: Low intravascular pressure Pulsation of capillaries Peculiarities of splanchnic hemodynamics: Two capillary networks are present High protein permeability in the liver Peculiarities of fetal hemodynamics: Opened ductus Botalli (ductus arteriosus) Mix of oxygenated and deoxygenated blood Relatively high content of oxygen in umbilical vein Mean effective filling pressure of the heart ventricle is substantially affected by: -Ventricular contractility and heart rate -Blood volume -Intrathoracic pressure during inspirium In the condition of constant flow in the system of tubes: -The lateral inside pressure decreases in the diameter of the tube is reduced The major part of the blood volume is usually in: -Large veins The important property of the Purkinje fibres is: Fast conductance of impulses Mean rate of blood flow in the aorta is: -Inversely related to the diameter of aorta Peripheral vascular resistance is: -Resistance to blood flow in the systemic vasculature Decrease of the transmural pressure in the carotic sinus results in: -Increase of peripheral vascular resistance According to "myogenic mechanism" of the blood flow autoregulation the increase of the blood pressure in arterioles results in: -Increase of the peripheral vascular resistance Adrenergic stimulation of the heart results in: -Increase of the coronary blood flow The heart work almost equals: -Area of pressure / volume relationship of the ventricle The main cardiac and vasomotoric center is located in: -Pons and medulla oblongata In normal conditions is in capillaries: The small volume of blood (approx. 5%) only The first heart sound is: -Isovolumic contraction -1​st​ cardiac sound is the result of atrioventricular valve closure (mitral and tricuspid are atrioventricular valves) P wave in ECG is: -​At the beginning of atrial contraction Vasoconstriction activity of sympathetic is decreased after stimulation of: -Carotic sinus Cardiac output in resting person is approximately: -5.25 l/min Normal man has in 100 ml of blood approximately: -15 g of Hb The regional blood flow is regulated mainly by the local Metabolic activity in: -Muscle Cardiac index is the relation of: -Cardiac output and body surface area -The increase of pressure in carotid sinus results in: -Reflex bradycardia The common features of cardiac and skeletal muscles are: -​Both are striated -Both contain actin and myosin -Strength of contractin is related to the muscle length Renal hemodynamics: -it contains two capillary networks -the glomerular blood pressure is similar to arteriolar one The blood pressure is measured by method: -Of Korotkow sounds What is the colour designation of the standard Limb unipolar: Left hand – Yellow Right hand – Red Left foot – Green The third heart sound is heard: Physiologically in children and young people The threshold level of the cardiac membrane potential is: Minus 65mv The electrical axis of the heart is usually: Shifted to the left Shifted to the right Horizontal to vertical The critical level of the cardiac membrane potential is: Minus 35mv The action of the vagus nerve on the heart is: Negatively chronotropic Negatively inotropic Negatively dromotropic Negatively bathmotropic The action of the sympathetic nerves on the heart is: Positively dromotropic Positively bathmotropic Vasodilation can be generally: Active Passive Sympathetic cholinergic Parasympathethic cholinergic The normal systolic and diastolic pressure in men at rest is: 12-16/8-10.6 kPa 90-120/60-80 mmHg The most important control mechanisms in the heart is: Frank-Starling mechanisms The slowest impulse conduction is in: AV node The most convenient point of examination of arterial pulse: On the anterior surface of the wrist where the radial artery crosses the radius Carotid artery Percussion can be: Direct Indirect Comparative Topographic Peculiarities of renal hemoydnamics: Two capillary networks Skimming effect Skimming effect is most expressive in: Kidneys Humoral vasoconstriction is realized by: Thromboxan Vasopressin (ADH) Norepinephrine (also called noradrenaine or noradrealin) Angiotensin II The fastest impulse conduction is in: His bundle and Purkinje cells Humoral vasodilation is realized by: Atrial natriuretic peptide (ANP) Most of prostaglandins (PG12, PGE1) Milk acid EDRF, EDHF, Carbon dioxide Histamine Adenosine (during hypoxia) Physiological rhytm of the heart is: Sinus one (rhytm) is regular or irregular Stop of the blood flow in the coronary arteries is: Only during systole Only in the left coronary artery Lasting (duration) of PQ interval of ECG must be shorter than: 0.2 s QRS complex of ECG demonstrates: Depolarization of ventricles Where is the first heart sound situated in regard to the ECG: Immediately behind the complex QRS The Q wave of QRS complex of ECG is: Negative always Situated before R wave always The R wave of QRS complex of ECG is: Positive always Always after the Q wave The S wave of QRS complex of ECG is: Negative always Sometimes not present The S wave of the QRS complex is normally the highest in the leads: V1-V3 The negative P wave on the ECG: Is the typical finding in III, aVR, V1 and V2 Is always the pathological finding (?) The QRS complex on ECG is: Independent on the heart rate Not equally long in all leads The QT interval on ECG is: Equally long in all leads Very much dependent on the heart rate The PQ interval on ECG is: Equally long in all heart cycles The transition zone on ECG is evaluated in the leads: V1-V6 chest Which receptors are stimulated by adrenalin: More beta than alpha Which receptors are stimulated by noradreanlin (norepinephrine): More alpha than beta The absolute refractory period consists of the following parts of action potential: Phase 0,1,2 Phase 1,2,3 (?) The absolute refractory period is: Longer than the relative refractory period Shorter than the action potential Carotid output/l m2 of the body surface means: Cardiac index Depolarization is the following part of the action potential: Phase 0 Law of Laplace and Bernoulli principle are typical for the hemodynamics in: Capillaries Arteries The blood pressure is dependent on: Cardiac output Peripheral resistance Blood viscosity Quality of the vascular wall Typical patterns of action potentials in cardiac pacemaker is: Slow inward channels only Lack of phase 1 of action potential Local humoral control of the blood pressure (BP): Carbon dioxide produces vasodilation Prostaglandins produce mostly vasodilation Humoral control of the blood pressure (BP): The atrial natriuretic peptide ANP produces vasodilation Angiotensin II produces vasoconstriction and increase BP Catecholamines produce vasodilation via beta-receptors Catecholamines produce vasoconstriction via alpha-receptors Humoral control of the blood pressure (BP) – endothelial factors: The endothelium derived constricting factor EDCF produces vasoconstriction The endothelium derived relaxing factor EDRF produces vasodilation The endothelium derived hyperpolarizing produces vasodilation Endothelium derived hyperpolarizing factor (EDHF) produces: Vasodilation Peripheral nervous control of the blood pressure (BP): Peripheral nervous control is secured by the axon reflex The ganglion reflexes function in the region of the celiac ganglion only (?) Peripheral nervous control is sometimes independent of the central control (?) Hand-wrist maneuver Hand-grip test ​-activation of the sympathetic influences on the heart and slight tachycardia (10 beats/min more than at rest) Veins as blood reservoir Veins are blood volume reservoir influence blood pressure. - 60% Effect of blood viscosity on blood flow Higher blood viscosity leads to lower blood flow and vice versa. S​T interval if its isometric ST interval is isometric Diastolic volume is the largest volume of blood Normal ​End-diastolic Volume (EDV) ​in rest (healthy 70-kilogram man) = 110-120 mL Normal ​End-systolic Volume (ESV) ​in rest (healthy 70-kilogram man) = 40-50 mL Normal ​Stroke Volume (SV) ​in rest (healthy 70-kilogram man) = 70 mL Normal ​Ejection Fraction​ = ​SV/EDV ​= ​60% Maximum value of QRS complex​ - ​0.11 When systole which valves are close Atrioventricular valves (mitral &tricuspid) Vagus nerve - if it produces acetylcholine Vagus nerve releases acetylcholine Stimulating the vagus nerve sends acetylcholine throughout the body. Automacity hierachy- eg which most automatic e.g. SA node SA node is the most automatic Epinephrine/norepinephrine- effect on BP - Vasoconstriction – Epinephrine and norepinephrine from the adrenal medulla Occurs in response to increased physical activity, emotional excitement, stress •increases heart rate Epi, NE, and Thyroxine all have positive ionotropic effects and thus contractility Epinephrine and norepinephrine from the adrenal medulla ● Occurs in response to increased physical activity, emotional excitement, stress ● increase heart rate Epinephrine​ - released from adrenal gland - increases heart rate and contractility Effect of sympathetic (i.e. norepinephrine; but also epinephrine) − higher membrane permeability for Na+ and Ca2+ Epinephrine & Norepinephrine vasoconstriction Ca comes from sarcoplasm of cardiac cell Arterial impulses if they affect the venous flow • Poiseuille’s Law • Resistance - series - Parallel - Increase blood viscosity, decrease the arterial blood flow Capillary what is made of Capillary is made of basement membrane and endothelium. ECG range -30 to 105 T wave shows negative in which lead The T wave is typically negative in lead V6 in healthy people If phase 1 is always positive - yes and exact questions and answers: Phase 1 – temporary/brief repolarization. Open K+ channels allow some K+ to leave the cell Automaticity(Chronotropic effect) –Can produce electrical activity without outside nerve stimulation Conductivity(Dromotropic effect) –Ability to transmit an electrical stimulus from cell to cell throughout myocardium Excitability(Batmotropic effect) –Ability to respond to an electrical stimulus Contractility(Inotropic effect) –Ability of myocardial cells to contract when Stimulated by an electrical impulse Rhyrhmicity -Ability to beat, or the state of beating, rhythmically without external stimuli -Condition of being rhythmic Cardiac conductive system: conductive system is important for synchronized contraction Angiotensin renin system - which enzyme converts angiotensin I in angio II Angiotensin-activating enzyme (ACE) ADH - what does it do - Its two primary functions are to retain water in the body and to constrict blood vessels - Long term blood pressure regulation Anti-diuretic hormone = ADH ​- Promote ​water reabsorption​ by the kidney tubules. Many q which number is which phase, if it is depolarisation what ions come in and out, which one is plateau Phases 0 – depolarization - Due to gap junctions or conduction fiber action - Voltage gated Na​+​ channels open… close at 20mV 1 – temporary repolarization - Open K​+​ channels allow some K​+​ to leave the cell 2 – plateau phase - Voltage gated Ca​2+​ channels are fully open (started during initial depolarization) 3 – repolarization 4 – resting membrane potential -90mV - Ca2+ channels close and K+ permeability increases as slower activated K+ channels open, causing a quick repolarization - Plateau phase prevents summation due to the elongated refractory period High levels of Ca2+ cause: - ​higher contractility - finally, cardiac arrest in systole Lower levels of Ca2+ cause: - lower contractility High levels of K+ cause: - lower heart rate - lower contractility - ventricular arrhythmias - finally, cardiac arrest in diastole Lower levels of K+ cause (not needed): - longer QT interval - lower T wave − extra-systoles Acetylcholine effect Effect of parasympathetic (i.e. acetylcholine) higher membrane permeability for K+ (hyperpolarisation) decreases pacemaker rate by increasing potassium and decreasing calcium and sodium movement, as the pacemaker slows, so does your heart rate Decreases Blood pressure Chemoreceptors, baroreceptors, which nerves they are connected, what they measure, the effect Baroreceptors - located in the carotid sinus and in aortic arch Their function is to sense pressure changes by responding to change in the tension of the arterial wall. The baroreflex mechanism is a fast response to changes in blood pressure. Peripheral Chemoreceptors -carotid body -aortic body Peripheral chemoreceptors ​(or carotid and aortic bodies) are so named because they are sensory extensions of the ​peripheral ​nervous system into blood vessels where they detect changes in chemical concentrations. Peripheral ​chemoreceptors ​(carotid and aortic bodies) and ​central chemoreceptors ​(medullary neurons) primarily function to regulate respiratory activity. Brainbridge reflex - Volumoreceptors (type B in RA): ​volume loading ​conditions ​1. ​– ​Bainbridge response ​prevails (only ​HR ​is affected) The Bainbridge reflex, also called the atrial reflex, is an increase in heart rate due to an increase in central venous pressure. Increased blood volume is detected by stretch receptors (Cardiac Receptors) located in both atria at the venoatrial junctions. Depolarization Occurs when positively charged ions move inside cells causing interior to become positively charged – Change in electrical Charge over time Referred to as cell’s Action potential Repolarization Follows depolarization and occurs when: – Potassium leaves cell Causing positive charge to lower – Sodium and calcium are removed by special transport systems QRS complex The QRS complex reflects the rapid depolarization of the right and left ventricles. They have a large muscle mass compared to the atria and so the QRS complex usually has a much larger amplitude than the P-wave. ​80 to 120ms PR interval The PR interval is measured from the beginning of the P wave to the beginning of the QRS complex. The PR interval reflects the time the electrical impulse takes to travel from the sinus node through the AV node and entering the ventricles. The PR interval is therefore a good estimate of AV node function. ​120 to 200ms Normal cardiac axis (value ) -30- +90 What happens during inspiration Inspirium increases the sympathetic activity on the heart Ejection fraction Normal ​Ejection Fraction​ = ​SV/EDV ​= ​60% An ​ejection fraction (EF) ​is the fraction of blood ejected from a ventricle of the heart with each heartbeat. It is calculated by dividing the stroke volume by the end-diastolic volume. Level of Ca2+ and K+ (what happen if decrease and increase) Chemoreceptors, baroreceptors Rate of SA node, AV node (relationship) Question about function of angiotensin: Angiotensin promotes ​vasoconstriction Anti-diuretic hormone = ADH Promote water reabsorption by the kidney tubules. Aldosterone: Reabsorption in both sodium (NA+), water and salt Vasopressin: Vasoconstriction Thyroxin: -released from thyroid gland - increases heart rat (moderate increase also stimulates heart contractility, however, higher levels inhibit it NOTES: Non-nodal ​(Purkinje, atrial/ventricular myocytes, myocardium) Nodal ​(SA node, AV node) NODAL: Phase 0: ​Depolarization (increased Ca++ and decreased K+ conductances) (-40mV and -30mV) Phase 3: ​Repolarization (increased K+ and decreased Ca++ conductances) (completely repolarized about -60mV) Phase 4: ​Spontanous depolarization (increased Ca++ and decreased K+ conductances) (slow Na+ channels) NON-NODAL: Phase 0: ​Rapid depolarization (increased Na+ and decreased K+ conductances) (caused by a transient increase in fast Na+ channels though fast Na channels) (-70mV) Phase 1: ​Initial repolarization (decrease Na+ and increased K+ conductances) (it’s produced by an outward movement of K+ through special K channels) Phase 2: ​Plateau (increased Ca++ conductance)(Ca movement through Ca channels that open up when the membrane potential depolarized to about -40mV) Phase 3: ​Repolarization (increased K+ and decreased Ca++ conductances) (it occurs when K+ increased along with the inactivation of Ca++ channels) Phase 4: ​Resting potential (increased K+ , decreased Na+ and decreased Ca++ conducances) (very negative, -90mV because K channels are open) 1st sound ​= 25/45Hz, atrioventricular valves (tricuspid,mitral) closing during ventricular systole, PR interval 2nd sound ​= 50Hz, semilunar valves (aortic,pulmonary) closing,T wave end 3th sound ​= ventricular sound, 200ms after the second sound, from ventricular filling, slow diastole 4th sound ​= atrial sound, 100ms after the first sound, from atrial systole or pre-systole Autoregulation of blood flow: Rapid increase in arterial pressure causes immediate increase in blood fl