Circulation and the Heart

8/14/2019 Circulation and the Heart

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CIRCULATORYCIRCULATORY

SYSTEMSYSTEM

THE HEARTTHE HEART


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CIRCULATORY SYSTEMCIRCULATORY SYSTEM

BLOODBLOOD

BLOOD VESSELSBLOOD VESSELS

HEARTHEART


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BASIC HEART STRUCTUREBASIC HEART STRUCTURE

ANIMAL HEARTANIMAL HEART

ATRIUM/ATRIA (1 OR 2)ATRIUM/ATRIA (1 OR 2)

RECEIVE BLOOD RETURNING TO HEARTRECEIVE BLOOD RETURNING TO HEART MAMMALIAN HEART POSSESSES 2 ATRIAMAMMALIAN HEART POSSESSES 2 ATRIA

VENTRICLES (1 OR 2)VENTRICLES (1 OR 2)

PUMP BLOOD FROM THE HEARTPUMP BLOOD FROM THE HEART MAMMALIAN HEART POSSESSES 2MAMMALIAN HEART POSSESSES 2

VENTRICLESVENTRICLES


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BASIC HEART STRUCTUREBASIC HEART STRUCTURE

ANIMAL HEARTANIMAL HEART

ARTERIESARTERIES CARRY BLOOD FROM THE HEARTCARRY BLOOD FROM THE HEART

ARTERYARTERY ARTERIOLEARTERIOLE CAPILLARIESCAPILLARIES

CAPILLARIESCAPILLARIES SITE OF GAS AND NUTRIENT EXCHANGESITE OF GAS AND NUTRIENT EXCHANGE

VEINSVEINS RETURN BLOOD TO THE HEARTRETURN BLOOD TO THE HEART

CAPILLARIESCAPILLARIES VENULESVENULES VEINSVEINS


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FUNCTIONS OF THE HEARTFUNCTIONS OF THE HEART

TWO MAJOR DIVISIONSTWO MAJOR DIVISIONS PULMONARY CIRCUITPULMONARY CIRCUIT

CARRIES BLOOD TO LUNGS (GILLS)CARRIES BLOOD TO LUNGS (GILLS)

GAS EXCHANGE: LOSE COGAS EXCHANGE: LOSE CO22, GAIN O, GAIN O

22

RIGHT SIDE OF MAMMALIAN HEARTRIGHT SIDE OF MAMMALIAN HEART

SYSTEMIC CIRCUITSYSTEMIC CIRCUIT

CARRIES BLOOD TO BODY ORGANSCARRIES BLOOD TO BODY ORGANS GAS EXCHANGE: LOSE OGAS EXCHANGE: LOSE O

22, GAIN CO, GAIN CO

22

LEFT SIDE OF MAMMALIAN HEARTLEFT SIDE OF MAMMALIAN HEART


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HEART STRUCTUREHEART STRUCTURE

CHAMBERSCHAMBERS

ATRIAATRIA

RIGHT AND LEFTRIGHT AND LEFT SEPARATED BY INTERATRIAL SEPTUMSEPARATED BY INTERATRIAL SEPTUM

VENTRICLESVENTRICLES

RIGHT AND LEFTRIGHT AND LEFT SEPARATED BY INTERVENTRICULARSEPARATED BY INTERVENTRICULAR

SEPTUMSEPTUM


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BLOOD FLOW THROUGH THEBLOOD FLOW THROUGH THE

HEARTHEART RIGHT ATRIUMRIGHT ATRIUM

RECEIVES ORECEIVES O22-POOR BLOOD FROM BODY-POOR BLOOD FROM BODY

RIGHT VENTRICLERIGHT VENTRICLE

RECEIVES ORECEIVES O22-POOR BLOOD FROM RIGHT ATRIUM-POOR BLOOD FROM RIGHT ATRIUM PUMPS OPUMPS O22-POOR BLOOD TO LUNGS-POOR BLOOD TO LUNGS

LEFT ATRIUMLEFT ATRIUM RECEIVES ORECEIVES O22-RICH BLOOD FROM LUNGS-RICH BLOOD FROM LUNGS

LEFT VENTRICLELEFT VENTRICLE RECEIVES ORECEIVES O22-RICH BLOOD FROM LEFT ATRIUM-RICH BLOOD FROM LEFT ATRIUM

PUMPS OPUMPS O22-RICH BLOOD TO BODY ORGANS-RICH BLOOD TO BODY ORGANS


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HEART VALVESHEART VALVES

CONSIST OF FIBEROUS FLAPSCONSIST OF FIBEROUS FLAPS

ENSURE UNIDIRECTIONAL FLOWENSURE UNIDIRECTIONAL FLOW

OPEN AND CLOSE IN RESPONSE TOOPEN AND CLOSE IN RESPONSE TOPRESSURE DIFFERENCES BETWEENPRESSURE DIFFERENCES BETWEEN

SIDESSIDES

ATRIOVENTRICULAR (AV) VALVESATRIOVENTRICULAR (AV) VALVES SEMILUNAR VALVESSEMILUNAR VALVES


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ATRIOVENTRICULAR (AV) VALVESATRIOVENTRICULAR (AV) VALVES

RIGHT AV VALVERIGHT AV VALVE

A.K.A. TRICUSPID VALVEA.K.A. TRICUSPID VALVE LEFT AV VALVELEFT AV VALVE

A.K.A. BICUSPID VALVEA.K.A. BICUSPID VALVE

A.K.A. MITRAL VALVEA.K.A. MITRAL VALVE


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ATRIUMATRIUM VENTRICLEVENTRICLE VENTRICLE RELAXEDVENTRICLE RELAXED

VALVE OPENVALVE OPEN ATRIUMATRIUM VENTRICLE BLOOD FLOWVENTRICLE BLOOD FLOW

VENTRICLE CONTRACTSVENTRICLE CONTRACTS VENTRICLE PRESSURE INCREASESVENTRICLE PRESSURE INCREASES VALVE CLOSESVALVE CLOSES

PREVENTS BACK FLOWPREVENTS BACK FLOW


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PAPILLARY MUSCLESPAPILLARY MUSCLES CONTRACT WITH REST OF VENTRICLECONTRACT WITH REST OF VENTRICLE

PULL ON CHORDAE TENDINEAEPULL ON CHORDAE TENDINEAE

CHORDAE TENDINEAECHORDAE TENDINEAE CONNECT AV VALVE CUSPS TOCONNECT AV VALVE CUSPS TO

PAPILLARY MUSCLES OFPAPILLARY MUSCLES OF REINFORCE AV VALVESREINFORCE AV VALVES

PREVENT PROLAPSEPREVENT PROLAPSE


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SEMILUNAR VALVESSEMILUNAR VALVES

VENTRICLEVENTRICLE ARTERYARTERY VENTRICLE RELAXEDVENTRICLE RELAXED

PRESSURE HIGHER IN ARTERIESPRESSURE HIGHER IN ARTERIES VALVE CLOSEDVALVE CLOSED

VENTRICLE CONTRACTSVENTRICLE CONTRACTS PRESSURE HIGHER IN VENTRICLEPRESSURE HIGHER IN VENTRICLE VALVES FORCED OPENVALVES FORCED OPEN

BLOOD FLOWS FROM HEARTBLOOD FLOWS FROM HEART


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PERICARDIUMPERICARDIUM

DOUBLE-WALLED SACDOUBLE-WALLED SAC

ENCLOSES HEARTENCLOSES HEART CONTAINS PERICARDIAL FLUIDCONTAINS PERICARDIAL FLUID (5-30 ML)(5-30 ML)

GREATLY REDUCES FRICTIONGREATLY REDUCES FRICTION


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HEART WALLHEART WALL

EPICARDIUM (OUTER)EPICARDIUM (OUTER) A.K.A. VISCERAL PERICARDIUMA.K.A. VISCERAL PERICARDIUM

MYOCARDIUMMYOCARDIUM THICKEST LAYERTHICKEST LAYER

CARDIAC MUSCLECARDIAC MUSCLE

ENDOCARDIUMENDOCARDIUM SMOOTH INNER LININGSMOOTH INNER LINING

CONTINUOUS WITH BLOOD VESSELSCONTINUOUS WITH BLOOD VESSELS


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MYOCARDIUMMYOCARDIUM

THICKEST; CARDIAC MUSCLETHICKEST; CARDIAC MUSCLE MUSCLE FIBERS CONNECTED BYMUSCLE FIBERS CONNECTED BY

FIBROUS (PROTEIN) SKELETONFIBROUS (PROTEIN) SKELETON STRUCTURAL SUPPORTSTRUCTURAL SUPPORT

SOMETHING TO PULL AGAINSTSOMETHING TO PULL AGAINST

ELECTRICAL NONCONDUCTORELECTRICAL NONCONDUCTOR ALLOWS ATRIA AND VENTRICLES TOALLOWS ATRIA AND VENTRICLES TO

CONTRACT SEPARATELYCONTRACT SEPARATELY


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CARDIAC MUSCLE STRUCTURECARDIAC MUSCLE STRUCTURE

CARDIAC MUSCLE CELLSCARDIAC MUSCLE CELLS

MYOCYTES / CARDIOCYTESMYOCYTES / CARDIOCYTES STRIATEDSTRIATED

SHORT, THICK (50 100SHORT, THICK (50 100 M x 10 - 20M x 10 - 20 M)M)

BRANCHEDBRANCHED

SINGLE NUCLEUSSINGLE NUCLEUS

LESS DEVELOPED SR (SER)LESS DEVELOPED SR (SER) LARGER T-TUBULES (ADMIT CaLARGER T-TUBULES (ADMIT Ca++++))

JOINED VIA INTERCALATED DISKSJOINED VIA INTERCALATED DISKS


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CARDIAC MUSCLE STRUCTURECARDIAC MUSCLE STRUCTURE

INTERCALATED DISK FEATURESINTERCALATED DISK FEATURES

INTERDIGITATING FOLDSINTERDIGITATING FOLDS INCREASED SURFACE AREA CONTACTINCREASED SURFACE AREA CONTACT

MECHANICAL JUNCTIONSMECHANICAL JUNCTIONS FASCIA ADHERENS (ACTIN)FASCIA ADHERENS (ACTIN)

DESMOSOMESDESMOSOMES

ELECTRICAL JUNCTIONSELECTRICAL JUNCTIONS GAP JUNCTIONSGAP JUNCTIONS

ELECTRICALLY STIMULATE NEIGHBORSELECTRICALLY STIMULATE NEIGHBORS


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CARDIAC METABOLISMCARDIAC METABOLISM

EXCLUSIVELY AEROBICEXCLUSIVELY AEROBIC

MYOGLOBIN-RICH (STORED OMYOGLOBIN-RICH (STORED O22))

GLYCOGEN-RICH (STORED SUGAR)GLYCOGEN-RICH (STORED SUGAR)

LARGE MITOCHONDRIA (25% VS 2%)LARGE MITOCHONDRIA (25% VS 2%) MULTIPLE FUELS USABLEMULTIPLE FUELS USABLE

VULNERABLE TO OVULNERABLE TO O

22

DEFICIENCYDEFICIENCY

NOT PRONE TO FATIGUENOT PRONE TO FATIGUE (AEROBIC, NO O(AEROBIC, NO O

22DEBT, NO FATIGUE)DEBT, NO FATIGUE)


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CARDIAC RHYTHMCARDIAC RHYTHM

HEARTBEATHEARTBEAT

INVERTEBRATESINVERTEBRATES TRIGGERED BY NERVOUS SYTEMTRIGGERED BY NERVOUS SYTEM

VERTEBRATESVERTEBRATES TRIGGERED BY HEART ITSELFTRIGGERED BY HEART ITSELF


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CARDIAC RHYTHMCARDIAC RHYTHM

CARDIAC MYOCYTESCARDIAC MYOCYTES AUTORHYTHMICAUTORHYTHMIC

SPONTANEOUS DEPOLARIZATION ATSPONTANEOUS DEPOLARIZATION AT

REGULAR INTERVALSREGULAR INTERVALS SOME SPECIALIZED TO GENERATESOME SPECIALIZED TO GENERATE

ACTION POTENTIALSACTION POTENTIALS

CARDIAC CONDUCTION SYSTEMCARDIAC CONDUCTION SYSTEM SINOATRIAL (SA) NODESINOATRIAL (SA) NODE ATRIOVENTRICULAR (AV) NODEATRIOVENTRICULAR (AV) NODE


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CARDIAC RHYTHYMCARDIAC RHYTHYM

SINOATRIAL (SA) NODESINOATRIAL (SA) NODE

MYOCYTES IN RIGHT ATRIUMMYOCYTES IN RIGHT ATRIUM

PACEMAKERPACEMAKER INITIATES HEARTBEATINITIATES HEARTBEAT

DETERMINES HEART RATEDETERMINES HEART RATE

FIRING RATE REDUCED BY NERVESFIRING RATE REDUCED BY NERVES 70 80 BEATS PER MINUTE (BPM)70 80 BEATS PER MINUTE (BPM)


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SINOATRIAL (SA) NODESINOATRIAL (SA) NODE CELLS LACK STABLE RESTINGCELLS LACK STABLE RESTING

MEMBRANE POTENTIALMEMBRANE POTENTIAL

SPONTANEOUSLY DEPOLARIZE ANDSPONTANEOUSLY DEPOLARIZE ANDREPOLARIZE AT REGULAR INTERVALSREPOLARIZE AT REGULAR INTERVALS(~0.8 SEC)(~0.8 SEC)

EACH DEPOLARIZATION INITIATESEACH DEPOLARIZATION INITIATESONE HEARTBEATONE HEARTBEAT

GENERATE ACTION POTENTIALGENERATE ACTION POTENTIAL


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SA ACTION POTENTIALSA ACTION POTENTIAL

SPREADS THROUGHOUT ATRIALSPREADS THROUGHOUT ATRIAL

MYOCARDIUMMYOCARDIUM

ATRIA CONTRACT ~SIMULTANEOUSLYATRIA CONTRACT ~SIMULTANEOUSLY

SIGNAL REACHES AV NODE (50MSEC)SIGNAL REACHES AV NODE (50MSEC)

DELAYED AT AV NODE (100 MSEC)DELAYED AT AV NODE (100 MSEC) VENTRICLES FILL DURING DELAYVENTRICLES FILL DURING DELAY


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ATRIOVENTRICULAR (AV) NODEATRIOVENTRICULAR (AV) NODE

NEAR RIGHT AV VALVENEAR RIGHT AV VALVE

ELECTRICAL GATEWAY TOELECTRICAL GATEWAY TOVENTRICLESVENTRICLES

DISTRIBUTES SIGNAL TODISTRIBUTES SIGNAL TO

VENTRICULAR MYOCARDIUMVENTRICULAR MYOCARDIUM AV BUNDLEAV BUNDLE

PURKINJE FIBERSPURKINJE FIBERS


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SIGNAL TRAVELS FROM AV THROUGHSIGNAL TRAVELS FROM AV THROUGH

VENTRICULAR MYOCARDIUMVENTRICULAR MYOCARDIUM

VENTRICULES CONTRACTVENTRICULES CONTRACT

~SIMULTANEOUSLY~SIMULTANEOUSLY

(PAPILLARY MUSCLES CONTRACT(PAPILLARY MUSCLES CONTRACT

FIRST)FIRST)


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CARDIAC ACTION POTENTIALSCARDIAC ACTION POTENTIALS

PROLONGED DEPOLARIZATIONPROLONGED DEPOLARIZATION 200 - 250 MSEC VS. 2 MSEC200 - 250 MSEC VS. 2 MSEC

RESULT OF SLOW Ca++ CHANNELSRESULT OF SLOW Ca++ CHANNELS

SUSTAINED CONTRACTIONSUSTAINED CONTRACTION

LONGER REFRACTORY PERIODLONGER REFRACTORY PERIOD 200 MSEC VS. 1 2 MSEC200 MSEC VS. 1 2 MSEC

PREVENTS WAVE SUMMATION, TETANUSPREVENTS WAVE SUMMATION, TETANUS


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SYSTOLE / DIASTOLESYSTOLE / DIASTOLE

SYSTOLESYSTOLE CONTRACTION OF A HEART CHAMBERCONTRACTION OF A HEART CHAMBER

REFERS TO VENTRICLE UNLESSREFERS TO VENTRICLE UNLESS

OTHERWISE NOTEDOTHERWISE NOTED

DIASTOLEDIASTOLE PERIOD DURING WHICH A HEARTPERIOD DURING WHICH A HEART

CHAMBER RELAXES AND FILLS WITHCHAMBER RELAXES AND FILLS WITHBLOODBLOOD


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ELECTROCARDIOGRAMELECTROCARDIOGRAM

ELECTRICAL CURRENTS GENERATEDELECTRICAL CURRENTS GENERATED

IN THE HEART TRAVEL WEAKLYIN THE HEART TRAVEL WEAKLY

THROUGH ALL BODY TISSUESTHROUGH ALL BODY TISSUES

THESE CURRENTS CAN BE MEASUREDTHESE CURRENTS CAN BE MEASURED

USING ELECTRODES APPLIED TO THEUSING ELECTRODES APPLIED TO THE

SKINSKIN


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P WAVEP WAVE

SIGNAL FROM SA NODE DEPOLARIZES ATRIASIGNAL FROM SA NODE DEPOLARIZES ATRIA

ATRIAL SYSTOLE ~100 MSEC AFTER P WAVEATRIAL SYSTOLE ~100 MSEC AFTER P WAVEBEGINSBEGINS


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QRS COMPLEXQRS COMPLEX

FIRING OF THE AV NODEFIRING OF THE AV NODE

ONSET OF VENTRICULAR DEPOLARIZATIONONSET OF VENTRICULAR DEPOLARIZATION ATRIAL REPOLARIZATION / DIASTOLE OBSCUREDATRIAL REPOLARIZATION / DIASTOLE OBSCURED

VENTRICULAR SYSTOLE IMMEDIATELY AFTERVENTRICULAR SYSTOLE IMMEDIATELY AFTER


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S T SEGMENTS T SEGMENT

MYOCARDIAL ACTION POTENTIAL PLATEAUMYOCARDIAL ACTION POTENTIAL PLATEAU VENTRICLES ARE CONTRACTINGVENTRICLES ARE CONTRACTING

BLOOD EJECTED FROM VENTRICLESBLOOD EJECTED FROM VENTRICLES


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HEART SOUNDSHEART SOUNDS

FIRST AND SECOND HEART SOUNDSFIRST AND SECOND HEART SOUNDS S1 AND S2S1 AND S2 LUBB-DUPPLUBB-DUPP

OCCUR IN CONJUNCTION WITH HEARTOCCUR IN CONJUNCTION WITH HEARTVALVES CLOSINGVALVES CLOSING

BLOODSTREAM TURBULENCEBLOODSTREAM TURBULENCE

THIRD HEART SOUND (S3)THIRD HEART SOUND (S3) SOMETIMES HEARD IN CHILDREN ANDSOMETIMES HEARD IN CHILDREN ANDADOLESCENTSADOLESCENTS


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CARDIAC CYCLECARDIAC CYCLE

ATRIAL SYSTOLEATRIAL SYSTOLE

ATRIAL DYASTOLEATRIAL DYASTOLE

VENTRICULAR SYSTOLEVENTRICULAR SYSTOLE VENTRICULAR DIASTOLEVENTRICULAR DIASTOLE

QUIESCENT PERIODQUIESCENT PERIOD


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QUIESCENT PERIODQUIESCENT PERIOD

NO CONTRACTION OF ANY HEARTNO CONTRACTION OF ANY HEART

CHAMBERSCHAMBERS

ATRIA ARE FILLINGATRIA ARE FILLING


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ATRIAL SYSTOLEATRIAL SYSTOLE

SA NODE FIRESSA NODE FIRES ATRIA DEPOLARIZEATRIA DEPOLARIZE P WAVE OF ECG PRODUCEDP WAVE OF ECG PRODUCED ATRIA CONTRACTATRIA CONTRACT BLOOD PRESSURE IN ATRIABLOOD PRESSURE IN ATRIA

INCREASESINCREASES BLOOD FORCED INTO VENTRICLESBLOOD FORCED INTO VENTRICLES


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ISOVOLUMETRIC CONTRACTIONISOVOLUMETRIC CONTRACTION

ATRIA REPOLARIZE, RELAXATRIA REPOLARIZE, RELAX ATRIA IN DIASTOLE FOR REMAINDERATRIA IN DIASTOLE FOR REMAINDER VENTRICLES DEPOLARIZE, CONTRACTVENTRICLES DEPOLARIZE, CONTRACT VENTRICULAR PRESSURE INCREASESVENTRICULAR PRESSURE INCREASES AV VALVES CLOSEAV VALVES CLOSE

HEART SOUND S1HEART SOUND S1 NO BLOOD EJECTED YETNO BLOOD EJECTED YET


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VENTRICULAR EJECTIONVENTRICULAR EJECTION

VENTRICULAR PRESSURE EXCEEDSVENTRICULAR PRESSURE EXCEEDSARTERIAL PRESSUREARTERIAL PRESSURE

SEMILUNAR VALVES OPENSEMILUNAR VALVES OPEN BLOOD EJECTED INTO ARTERIESBLOOD EJECTED INTO ARTERIES NOT ALL BLOOD EXPELLEDNOT ALL BLOOD EXPELLED

AMOUNT EJECTED = STROKE VOLUMEAMOUNT EJECTED = STROKE VOLUME % = EJECTION FRACTION% = EJECTION FRACTION


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ISOVOLUMETRIC RELAXATIONISOVOLUMETRIC RELAXATION

EARLY IN VENTRICULAR DIASTOLEEARLY IN VENTRICULAR DIASTOLE

BLOOD BRIEFLY FLOWS BACKWARDSBLOOD BRIEFLY FLOWS BACKWARDS SEMILUNAR VALVES CLOSESEMILUNAR VALVES CLOSE

HEART SOUND S2HEART SOUND S2

AV VALVES NOT YET OPENAV VALVES NOT YET OPEN NO BLOOD TAKEN IN YETNO BLOOD TAKEN IN YET


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VENTRICULAR FILLINGVENTRICULAR FILLING

VENTRICULAR PRESSURE DROPSVENTRICULAR PRESSURE DROPS AV VALVES OPENAV VALVES OPEN VENTRICLES BEGIN TO FILLVENTRICLES BEGIN TO FILL HEART SOUND S3HEART SOUND S3 (COMPLETELY FILLED BY ATRIAL(COMPLETELY FILLED BY ATRIAL

SYSTOLE)SYSTOLE) P WAVE PRODUCEDP WAVE PRODUCED


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CARDIAC OUTPUTCARDIAC OUTPUT

HEART RATE (HR) (BEATS/MIN)HEART RATE (HR) (BEATS/MIN) ~75 BPM AT REST~75 BPM AT REST

STROKE VOLUME (SV)STROKE VOLUME (SV) ~70 ML/BEAT AT REST~70 ML/BEAT AT REST

CARDIAC OUTPUT (CO)CARDIAC OUTPUT (CO) CO = HR * SVCO = HR * SV

75 * 70 = 5,000 ML/MIN AT REST75 * 70 = 5,000 ML/MIN AT REST

CARDIAC OUTPUT IS NOT CONSTANTCARDIAC OUTPUT IS NOT CONSTANT


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CARDIAC OUTPUT IS NOT CONSTANTCARDIAC OUTPUT IS NOT CONSTANT

RESTINGRESTING ~5 LITERS/MIN RESTING (TOTAL VOLUME)~5 LITERS/MIN RESTING (TOTAL VOLUME)

VIGOROUS EXERCISEVIGOROUS EXERCISE ~21 LITERS/MIN IN GOOD CONDITION~21 LITERS/MIN IN GOOD CONDITION

~35 LITERS/MIN OLYMPIC ATHLETE~35 LITERS/MIN OLYMPIC ATHLETE

CO = HR * SV,CO = HR * SV, CO INCREASED BY HR OR SV INCREASECO INCREASED BY HR OR SV INCREASE


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HEART RATEHEART RATE

EASILY MEASURED (PULSE)EASILY MEASURED (PULSE)

70 80 AVERAGE RESTING RATE70 80 AVERAGE RESTING RATE TACHYCARDIA: RESTING >100 BPMTACHYCARDIA: RESTING >100 BPM

BRACHYCARDIA: RESTING


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REGULATED BY CARDIAC CENTER OFREGULATED BY CARDIAC CENTER OF

MEDULLA OBLONGATAMEDULLA OBLONGATA CARDIOACCELATORY CENTERCARDIOACCELATORY CENTER

CARDIOINHIBITORY CENTERCARDIOINHIBITORY CENTER


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CARDIOACCELATORY CENTERCARDIOACCELATORY CENTER

THORACIC SPINAL CORDTHORACIC SPINAL CORD CARDIAC ACCELERATOR NERVESCARDIAC ACCELERATOR NERVES

SECRETE NOREPINEPHRINESECRETE NOREPINEPHRINE

BINDS TO RECEPTORS IN HEARTBINDS TO RECEPTORS IN HEART INCREASES HEART RATEINCREASES HEART RATE


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CARDIOINHIBITORY CENTERCARDIOINHIBITORY CENTER

VAGUS NERVESVAGUS NERVES SECRETE ACETYLCHOLINESECRETE ACETYLCHOLINE

SEND SIGNALS TO AV AND SA NODESSEND SIGNALS TO AV AND SA NODES

FIRE LESS FREQUENTLYFIRE LESS FREQUENTLY INTRINSIC HEART RATE IS 100 BPMINTRINSIC HEART RATE IS 100 BPM


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CARDIAC CENTER RECEIVES INPUTCARDIAC CENTER RECEIVES INPUT

FROM MULTIPLE SOURCESFROM MULTIPLE SOURCES PROPRIORECEPTORSPROPRIORECEPTORS

PHYSICAL ACTIVITYPHYSICAL ACTIVITY

BARORECEPTORSBARORECEPTORS

BLOOD PRESSUREBLOOD PRESSURE CHEMORECEPTORSCHEMORECEPTORS

pH, [OpH, [O22], [CO], [CO22]]


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STROKE VOLUMESTROKE VOLUME

GOVERNED BY THREE FACTORSGOVERNED BY THREE FACTORS PRELOADPRELOAD

CONTRACTILITYCONTRACTILITY

AFTERLOADAFTERLOAD


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PRELOADPRELOAD

VENTRICULAR MYOCARDIUM TENSIONVENTRICULAR MYOCARDIUM TENSION

PRIOR TO CONTRACTIONPRIOR TO CONTRACTION SKELETAL MUSCLES MASSAGE VEINS ANDSKELETAL MUSCLES MASSAGE VEINS AND

INCREASE VENOUS RETURNINCREASE VENOUS RETURN MORE TENSION WHEN MYOCARDIUMMORE TENSION WHEN MYOCARDIUM

CONTRACTSCONTRACTS MORE FORCEFUL CONTRACTIONMORE FORCEFUL CONTRACTION MORE BLOOD EXPELLEDMORE BLOOD EXPELLED


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CONTRACTION FORCE FOR A GIVENCONTRACTION FORCE FOR A GIVEN

PRELOADPRELOAD

MYOCYTES MORE RESPONSIVE TOMYOCYTES MORE RESPONSIVE TO

STIMULATIONSTIMULATION

AFFECT CaAFFECT Ca++++ CONCENTRATIONSCONCENTRATIONS

(Ca(Ca++++ REQUIRED FOR MUSCLEREQUIRED FOR MUSCLE

EXCITATION / CONTRACTION)EXCITATION / CONTRACTION)


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CaCa++++ CONCENTRATIONS INCREASED BYCONCENTRATIONS INCREASED BY EPINEPHRINE, NOREPINEPHRINEEPINEPHRINE, NOREPINEPHRINE

GLUCAGON, cAMPGLUCAGON, cAMP

DIGITALISDIGITALIS


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AFTERLOADAFTERLOAD

BLOOD PRESSURE IN ARTERIES JUSTBLOOD PRESSURE IN ARTERIES JUST

OUTSIDE OF SEMILUNAR VALVESOUTSIDE OF SEMILUNAR VALVES

INCREASED AFTERLOAD REDUCESINCREASED AFTERLOAD REDUCES


CAUSED BY ANYTHING IMPEDINGCAUSED BY ANYTHING IMPEDING

ARTERIAL CIRCULATIONARTERIAL CIRCULATION


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EFFECTS OF EXERCISEEFFECTS OF EXERCISE

INCREASED CARDIAC OUTPUTINCREASED CARDIAC OUTPUT

VENTRICULAR HYPERTROPHYVENTRICULAR HYPERTROPHY INCREASED STROKE VOLUMEINCREASED STROKE VOLUME

PROPRIORECEPTORSPROPRIORECEPTORS

SIGNALS FROM MUSCLES/JOINTSSIGNALS FROM MUSCLES/JOINTS

INCREASED VENOUS RETURNINCREASED VENOUS RETURN INCREASED PRELOADINCREASED PRELOAD

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Circulation and the Heart