18 Cardiac Pump Flashcards by Jake Evans

What is the pressure and volume comparison between the right heart and the left heart?

Pressure is lower in right. Volume is the same.

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What is phase 1 of the cardiac cycle?

inflow–stratified as early (MV opens inflow) and late (flow slows tremendously and atrium contract

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What is it called when the mitral valve is open, but there is little flow into the ventricle?

Diastasis

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What are the three components of phase 1 of the cardiac cycle?

ventricular filling, diastasis and atrial contraction

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What is phase 2 of the cardiac cycle?

isovolumetric contraction— beginning of systole, follows start of QRS, mitral valve closes, and aortic valve is still closed.

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What is phase 3 of the cardiac cycle?

Outflow phase–LV pressure exceeds aortic pressure and AV opens

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What are the two ejection phases of the outflow phase?

rapid and decreased

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What is phase 4 of the cardiac cycle?

isovolumetric relaxation– AV closes, begin diastole, MV stays closed

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What is the initiating event of excitation contraction coupling in cardiomyocytes?

AP propagating from adjacent cardiomyocyte rather than neuromuscular junction

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Are t-tubules more or less developed in cardiac muscle than in skeletal muscle?

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What regulates contraction and relaxation in cardiac muscle cells?

calcium

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What are the three stages of cardiomyocyte relaxation involving Ca 2+?

dissociation from troponin c
Extrusion of Ca 2+ out of Myocyte (Na CA exchanger and Ca Pump)
re-uptake into SR (SERCA)

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is the non-contractile elastic components of cardiac muscle more or less distensible than skeletal muscle?

much less

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what is the major elastic component protein responsible for the distensibility property of muscle cells?

titin

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What two factors determine active length tension in cardiac muscle

degree of actin myosin overlap and

2. capacity of Ca2+ to bind to contractile proteins at varying sarcomere lengths.

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Is cardiac muscle activated in a more narrow or more broad sacomere length than skeletal muscle?

much narrower sarcomere length.

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cardiac output is equal to?

HR x stroke volume

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Cardiac function is dependent on what 3 variables?

preload, after load, and intrinsic contractility

What is the initial sarcomere length measured as end diastolic volume?

pre-load

What is the force that the contracting myocardium must overcome or arterial pressure in beating heart?

afterload

A decrease in afterload causes what shift in the cardiac function curve?

up and to the left

An increase in afterload causes what shift in the cardiac function curve?

down and to the right.

An increase in intrinsic contractility causes what shift in the cardiac function curve?

up and to the left

A decrease in the intrinsic contractility causes what shift in the cardiac function curve?

down and to the right

which ventricle contracts like bellows with the free wall moving toward septum and base and apex are moving closer together?

Right ventricle

which ventricle has circular oriented fibers that constrict and and longitudinal fibers to shorten the chamber?

left ventricle-- twisting movement during contraction due to spiral orientation of fibers

What is the percent of blood pumped out of the ventricle during systole called?

ejection fraction

The PV loop is confined to what region on the passive and active length-tension curves graph?

between the active and passive length tension curves?

What does segment A-C stand for in the pressure volume loop?

ventricular filling

What does segment D-F stand for in the pressure volume loop?

ventricular ejection

What does segment C-D stand for in the pressure volume loop?

isovolumetric contraction

What does segment F-A stand more in the pressure volume loop?

isovolumetric relaxation

Is intrinsic contractilit dependent or independent of loading conditions?

Independent

What does increased contractility do to the PV loop?

Increases slope of ESPVR line and the heart ejects to lower volume (increasing stroke volume)

Does Increasing end-diastolic volume (AC segment is larger) increase or decrease stroke volume?

increases stroke volume (increases volume change during ejection)

What can increase the isovolumetric segment (segment CD gets larger, LV pressure is increased)?

Increase in aortic pressure

What does and increase in aortic pressure do to the stroke volume?

It decreases it (ventricle must increase tension before being able to eject)

What does the area within the PV loop represent?

WORK necessary to pump blood in one cardiac cycle

What is the total energy equation for one heart beat?

E=PV+1/2mv^2+kTt

What is the energy required to generate tension during isovolumetric contraction called?

TENSION HEAT (k x T(wall tension) x delta t(length of time in isovolumetric contraction))

What component is the major determinant of the total energy requirement of the heart?

TENSION HEAT (resting=97%, exercise=90%)

What is the majority of the work the heart spends trying to do?

generate enough pressure to open aortic valve

what is a good estimation (equation) for cardiac workload?

HR x mean blood pressure

What is phospholambin?

sarcoplasmic reticulum membrane protein that regulate Ca uptake through SERCA. Phosphorylation releases the inhibition