cardiac pumpkul13.pptbr

7/30/2019 Cardiac PumpKul13.Pptbr

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Suyasning HI

Physiology/Biochemistry Department

School of Medicine

Warmadewa University


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The Cardiac Cycle

Work Output of the Heart

Preload, Afterload and Contractility

Regulation of Heart Function The FrankStarling Mechanism

Measurement of Cardiac Output


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Pulmonary circuit

blood to and from the lungs

Systemic circuit

blood to and from the rest of the body

Vessels carry the blood through the circuits

Arteries carry blood away from the heart

Veins carry blood to the heart

Capillaries permit exchange


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During systole, blood accumulates in the atria.

At end systole, the higher pressure forces openthe AV valves causing rapid ventricular filling.

This lasts about 1/3.

In the middle 1/3, there is minimal flow.

In the last 1/3, the atria contracts to deliver up

to 20% of the total ventricular volume.


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At the start of systole, the intraventricularpressure rises which closes the AV valves.

For approximately 0.02 to 0.03 seconds, the

pressure continues to rise but is less than thatrequired to open the semilunar valves.

This is called isovolumic contraction becausethe ventricular volume does not change.


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Once the semilunar valves open the ejectionphase begins.

About 70% of the total blood ejected occurs in

the first 1/3. This is called the rapid ejection period

The final 30% empties in the next 2/3 and is

called the slow ejection period.


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At end-systole, ventricular relaxation beginssuddenly and causes intraventricular pressureto fall rapidly.

The semilunar valves close once its pressure isgreater than intraventricular pressure.

For 0.03 0.06 seconds the muscle continues torelax, pressure continues to fall but no fillingoccurs because the AV valves are still closed.

This is the period of isovolumic relaxation.


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After the aortic valve opens, blood enters theaorta, stretching it and causes the pressure torise to 120 mmHg.

An incisura occurs just before the aortic valvecloses from a short backward flow of blood.

During diastole, the aortic pressure slowly fallsas blood flows out to the venous side.


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The stroke work output of the heart is theamount of energy converted to work per beat.

Two forms of work output:

Volume pressure (external) work: moving bloodfrom the low pressure veins to high pressurearteries.

Kinetic energy of blood flow: accelerate the blood to

its velocity of ejection. RV external work is 1/6 of the LV because of

the six fold difference in systolic pressure.


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Understand how thesystolic and diastolicpressure curves arederived.

By combining the enddiastolic and systoliccurves, the volume-pressure diagram can

be defined. The area inside the VP

diagram is the EW.


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Preload can be described as the stressexperienced at end-diastole

Preload=(EDP x EDR)/2w

Thus, preload represents all the factors thatcontribute to passive ventricular wall stress (ortension) at end diastole.

This means that EDP (P) or EDV (R) contributeto, be should not be equated to preload.


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Laplaces Law can be used to describe afterloadas ventricular stress during systolic ejection.

Therefore, stress=TP x R/2w

Afterload represents all the factors thatcontribute to total myocardial wall stress (ortension) during systolic ejection.

Arterial pressure and TPR contribute toafterload but should not be equated withafterload.


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Focusing on wall stress is important

Metabolic cost is related to the wall tension

The greater the tension, the greater the oxygen

demand. Physiological and therapeutic regimens reduce wall

stress and restore oxygen supply and demand.

The relationship among P, R and w provides a

clear physiological explanation for the differentpatterns of hypertrophy and remodelling.


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Gambaran tentang aktivitas

pompa jatung maupun keadaan

pembuluh darah itu sendiri. Macam denyut jantung

:Resting Heart Rate (RHR)

Maximal Heart Rate (MHR)

Heart Rate Reverse (HRR)

Training Heart Rate (THR)


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RESTING HEART RATE (RHR)

FREKWENSI DENYUT JANTUNG ISTIRAHAT= DENYUT JANTUNG SEBELUM LATIHAN

Angka normal pada manusia dewasa 60 -100 kali

permenit< 60 x per menit : Bradikardi

> 100 x per menit : Takikardi

Resting Heart Rate (RHR)

Resting Heart Rate (RHR)





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MAXIMAL HEART RATE (MHR)

ESTIMATED MHR /

FREKWENSI DENYUT JANTUNG

MAKSIMAL

MISAL USIA 20 Th MHR = 220 20

=200 KALI PERMENIT


MHR = 220 USIA

(RHR)

(MHR)

(HRR)

(THR)


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HEART RATE RESERVE (HRR)SELISIH ANTARA MHR DENGAN RHR

Contoh :

MHR usia 19 tahun = 220 - 19 = 221

x / MENIT

RHR wanita dewasa = 72 x / menit

maka HRR = 221 72

= 149 x / menit


(RHR)

(MHR)

(HRR)

(THR)

HRR = MHR RHR


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TRAINING HEART RATE (THR) /DENYUT JANTUNG LATIHAN / KERJA

= DENYUT JANTUNG YANG DIHARAPKAN

SELAMA BEKERJA / LATIHAN

RUMUS KARVONEN :


THR = ( % DOSIS LATIHANx HRR) + RHR


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Kontraksi maksimal jantung

Sistolik adalah tekanan dalam arteri yangterjadi saat dipompanya darah dari

jantung ke seluruh tubuh.

PENGERTIAN FASE DIASTOLIK

sisa tekanan dalam arteri yaitu saat jantung

beristirahat


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The amount of blood pumped by the heart isdetermined by the rate of blood flow from theveins (venous return).

The intrinsic ability of the heart to adapt toincreasing volumes of blood is the Frank-Starling mechanism.

With the extra delivery of blood, the cardiacmuscle contracts with greater force because ofimproved actin/myosin interaction.


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The ventricularfunction curve is away of expressing theFrank-Starling

mechanism. Increases in atrial

pressure causes anincrease volume and

strength of contractionwhich causes anincrease in cardiacoutput.


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Suppose blood flow is Q(ml/s) and q mg of dye isinjected.

If the concentration of dyeis continually measured

farther downstream, acurve of the dyeconcentration, c, isrecorded as a function oftime, t.

The amount of dye at pointB between the time t1 andt2 will be q = cQ(t2-t1).

Therefore, Q = q/(t2-t1)c


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The Cardiac Cycle

Work Output of the Heart

Preload and Afterload and Contractility

Regulation of Heart Function The FrankStarling Mechanism

Measurement of Cardiac Output


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Wall Stress An increase in wall stress achieved by either increasesd

LV size or intraventricular pressure will increasemyocardial oxygen uptake.

This is because a greater rate of ATP use is required as themyofibrils develop greater tension.

Wall Stress, Preload and Afterload Preload can now be defined as the wall stress at the end

of diastole and therefore at the resting maximal restinglength of the sarcomere.

Afterload, being the load on the contracting myocardium,is also the wall stress during LV ejection.


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Peak systolic wall stress reflects the three majorcomponents of the afterload-peripheral resistance, arterialcompliance, and peak intraventricular pressure.

Preload

The stretch of the individual sarcomere regulates theperformance of the heart.

Afterload This is the force against which muscle contracts.

Contractility This is the intrinsic ability of the heart muscle to generate

force and to shorten. It is manifest as the rate of pressuredevelopment and shortening from any preload.


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Ventricular Function Curve

The dependancy of stroke volume on preload wasdescribed more than 100 years ago by Otto Frankand E.H. Starling and since then has been called theFrank-Starling mechanism. Using this relationshipbetween preload and stroke volume or stroke work,a ventricular function curve can be consructed byplotting stroke work at various levels of preload.


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cardiac pumpkul13.pptbr

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