Cardiac physiologyLearning objectives:Compare and contrast the left and right side of the circulationWhat factors determine how a fluid flows through a tube?Trace a drop of blood through the heart and list the structures, in order, that it flows byDescribe spread of electrical excitation over the heartBe able to label an entire normal ECG and explain the various wave forms representWhat kinds of heart pathologies can an ECG diagnose in general?Be able to answer objective questions number 13 and 14 at the end of the chapter based on the cardiac cycleBe able to explain the left ventricular volume curve and aortic pressure curve in the cardiac cycle. Include comments on heart sounds.Describe the extrinsic and intrinsic factors that control cardiac outputWhat is the sequence of events for atherosclerotic plaque formation and how can this lead to myocardial infarction?Introduction principlesComponents of the circulatory systemHeartDevelops pressure that imparts energy & momentum to the blood thereby pushing the blood through the resistance of blood vesselsAll fluids move in tubes require a pressure difference between the ends of the tubes. In the body, this pressure difference is due to the mechanical action of the heartBlood vesselsTube-like conduits that distribute blood to nearly every cell in the bodyARTERIES- AWAY FROM HEARTVEINS- TO THE HEARTComponents of the circulatory systemBloodThe fluid medium that transports blood cells, nutrients, ions, gases, metabolic waste products, hormones, toxins, bacteria, viruses, antibodies, heatAbove substances are either dissolved in blood (e.g. ions, gases) or are suspended in the blood (e.g. blood cells)The heart is a 4-chambered dual pumpThe right side of the heart pumps approximately 5 liters/min of blood to the pulmonary circulation, while, at the same time, the left side of the heart is pumping 5 liters/min of blood to the systemic circulationLEFT AND RIGHT CARDIAC OUTPUTS (5L/MIN) OF THE HEART ARE HOMEOSTATICALLY MAINTAINED TO BE EQUALArteries always convey blood away from the heartVeins always convey blood to the bloodpulmonary circulation- (RIGHT SIDE OF HEART)systemic circulation- (LEFT SIDE OF HEART)Basic physics of fluid flowing in tubesFluid pressure is directly proportional to the energy and momentum contained within the tube. The greater the energy and momentum, the greater the fluid pressure.Fluids move through tubes ONLY IF THERE IS A PRESSURE DIFFERENCE BETWEEN THE TWO ENDS OF THE TUBE and if flow resistance is not excessiveFluid moves from high to low pressureHeart Gross AnatomyTHICKINESS OF LEFT VENTRICULAR WALL IS GREATER BECAUSE OXYGENATED BLOOD MUST FLOW THROUGH THE AORTAchanges in pressure across the heart valve will open or close the valveSYSTOLE- CONTRACTION & EMPTYING PHASE OF ATRIA OR VENTRICLESDIASTOLE- RELAXATION & FILLING PHASE OF ATRIA OR VENTRICLESN.B.: typically when "systole" or "diastole" are stated without additional qualification, the person is referring to ventricular systole and ventricular diastole rather than events in the atriaNOTE: 120/80 IS NORMAL BLOOD PRESSUREHeart valve anatomyRight side of the heartRight atroventricular valve (a.k.a. tricuspid)Pulmonary semilunar valveLeft Side of the HeartLeft atrioventricular valve (aka bicuspid, mitral)Aortic semilular valveVENTRICULAR DIASTOLEATROVENTRICULAR VALVES ARE OPENVENTRICULAR SYSTOLEPULMONARY SEMILUNAR VALVE AND AORTIC VALVE ARE OPENStart of New material for Exam 3Heart wall has 3 layersEpicardiumA thin outer layer of epithelial cellsNot involved in contractionSecreting fluid that goes into pericardium sackMyocardiumThick middle layer of striated cardiac muscle cells, coronary blood vessels, and autonomic nerve fibersEndocardium (remember: endocardium-endothelium)A thin inner layer (a little thicker than epicardium) of endothelial cellsDirectly contacts blood in heart chamberContinues as endothelium of blood vesselsHeart muscle is arranged in a spiral fashion that results in a "wringing out" motion during ventricular systoleCardiac muscle fibers have special cell-cell junctions called intercalated disksDesmosomes“spot weld” of adjacent plasma membrane that provides mechanical couplinggap junctionsallows ions to cross quickly from one cell to it neighbor thus transmitting changes in trans-membrane potentialas a consequence of this mechanical and electrical coupling of adjacent cardiac cells, the entire heart acts as a functional syncytiumi.e., when one cell changes its transmembrane potential, the rest of the cells quickly follow suitthis provides a basis for a coordinated, synchronous contraction of the heart as required to efficiently pump bloodinfer heart valve action, but you are not listening to the heart valves themselvesAuscultation- accomplished by placing the stethoscope superficial to the chamber or vessel into which the blood has passed and basically in line with the axis of the valve orificeStethoscopes are used to auscultate heart sounds, lung air flow, and bowel sounds.A stethoscope amplifies mechanical vibrations resonating in the chest cavity due to blood being suddenly stopped when valves close.A stethoscope does not technically "hear" the actual valve cusps touch... just the effect of the valve closurepulmonary valveaortic valvemitral valvetricuspid valve (on right side of the heart)ALL PHYSIANS TAKE MONEYHeart electrophysiologyMyocardiumThick layer- middle layerComposed of two cell typesCardiac muscle fibersDo not initiate their own action potentialsInnervated by sympathetic nervous system onlyAdrenergic receptors (norepinephrine BINDS)Autonomic ganglia- acetylcholine (nicotinic receptors)Comprise 99% of myocardiumDo the MECHANICAL WORK of generating blood pressureAutorythmic (pacemaker) cellsComprise remaining 1% of myocardiumExhibit an intrinsic pacemaker activity- spontaneously generate action potentials without enquiring any neural or hormonal inputsDetermine heart rateInnervated by BOTH sympathetic and parasympathetic nervous systemare highly modified cardiac muscle fibers that lost their contractile machinery so do not appear striated under a microscopethus do not contribute to developing blood pressuremake up nodes and fiber bundles of the Cardiac Conduction SystemMyosin filamentsCalcium-trigger-calciumAutorythmic cells- keeps beat of the heartNo resting membrane potential. Constantly depolarizing.slow depolarization phase (pacemaker potential)Na+ comes into the cellRapid depolarization (Rapid upstroke) Phaseonce