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Cardio Quiz Bowl > Cardiac Contraction And Relaxation > Flashcards

Cardiac Contraction And Relaxation Flashcards

1
Q

Cardiomyocytes constitute how much of the total ventricular volume?

A

75%

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2
Q

Major component of extracellular matrix?

A

Myofiber

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3
Q

Also known as the calcium release channels

A

Ryanodine receptors

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4
Q

Site of calcium binding in the myocytes that initiate contraction?

A

Troponin C

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5
Q

The interaction of the myosin heads with the actin filaments that is switched on when calcium binds is known as?

A

Cross-bridge cycling

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6
Q

Contraction strength is independent of sarcomere length (eg. Increased itnracellular calcium)

A

Positive inotoropic state

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7
Q

Central regulator of cardiac contraction and relaxation

A

Calcium

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8
Q

Calcium channel where dihydropyridines act on?

A

L - type calcium channels

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9
Q

Shape of ventricular myocytes

Atrial myocyte

Purkinjie cells

A

VM - long and narrow

AM - eliptical

PC - long and broad

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10
Q

This cell organelle is involved in the Interaction of thick and thin filaments during contraction cycle

A

Myofibril

Approx 50-60% of cell volume

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11
Q

This cell organelle is involved in the transmission of electrical signal from sarcolema to cell interior

A

T-system

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12
Q

This cell organelle takes up and releases calcium during contraction cycle

A

Sarcoplasmic reticulum

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13
Q

Organelle involved in the calcium storage and release?

A

SR terminal cisternae

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14
Q

Orgagnelle involved in control of ionic gradients, channels for ions (action potential), maintenance of cell integrity, receptor for drugs and hormones

A

Sarcolemma

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15
Q

Organelle where cytosolic volume within which calcium rises and falls

A

Sarcoplasm

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16
Q

Troponin that stabilises troponin T and tropomyosin to block cross-bridge binding?

A

Troponin I

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17
Q

A large elastic protein that connects the myosin and the M-line to the Z-line

A

Titin

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18
Q

This phase of the cardiac action potential corresponds to plateau phase

A

Phase 3

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19
Q

This phase of cardiac action potential corresponds to resting state

A

Phase 4

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20
Q

Phase of cardiac action potential where calcium channels open to balance the potassium rectifiers

A

Phase 3

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21
Q

Resting membrane potential is how many mV?

A

-90

22
Q

Threshold for cardiac muscle action potential?

A

-70 mV

23
Q

This effect occurs when there is increased uptake of calcium by the sarcoplasmic reticulum leading to enhance relaxation of the cardiac myocytes?

A

Lusitropic effect

24
Q

Type of calcium channel that has a more negative voltage, short bursts of opening and do not interact with calcium antagonist drugs.

A

T-type (tamad)

25
Q

Type of calcium channel concentrated in the T tubules and jSR. Inihbitted by CCB drugs.

A

L type calcium channels

26
Q

This refer to increase or decrease in coduction of action potential

A

Dromotropy

27
Q

Phase of cardiac cycle after mitral closure and before aortic valve opening where the volume remains fixed is known as?

A

Isovolumic contraction

28
Q

Normally LV pressure is between how many mmHG?

A

8-15 mmHG

29
Q

This aortic recoil maintains blood flow from the left ventricle to the aorta despite rapid decline

A

Windkessel effect

30
Q

Phase where the aortic valve and the mitral valve are closed but no change in the LV volume occurs after systole

A

Isovolumic relaxation

31
Q

Lasts from the start of isovolumic contraction to the peak of the ejection phase

A

Physiologic systole

32
Q

The interval between the first heart sound (M1) to the closure of the aortic valve (A2)

A

Cardiologic systole

33
Q

This heart sound corresponds to rapid filling of the ventricle or increased LV diastolic pressure, wall stiffness, or rate of filling

A

Protodiastole or S3

34
Q

Describes the degree of myocardial stretch or distention before contraction has started and best presented by LVEDV

A

Preload

35
Q

Refers to forces opposing LV ejection. More accurately described as aortic impedance or elastance

A

Afterload

36
Q

Used to measure venous filling pressure or stroke volume indirectly

A

Swan-ganz catheter

37
Q

Refers to the true distending pressure that determines LV preload volume calculated by EDP - external pericardial pressure

A

Left ventricular transmural pressure

Estimated by difference between EDP and right atrial pressure

38
Q

A slow inotropic adaptation where the inotropic state of the heart increases such as when aortic pressure is elevated abruptly

A

Anrep effect

39
Q

Wall stress = (pressure x radius)/ (2 x wall thickness)

A

Laplace’s law

Mnemonic

S= PxR/ 2xWT

SPRWT “SPRoWT”

40
Q

This is the wall stretch at the end of diastole where the resting length of the sarcomere is maximal

A

Preload

41
Q

This reflects the 3 major components of afterload (PVR, Arterial compliance, peak intraventricular pressure)

A

Peak systolic wall stress

42
Q

This measure of the LV afterload is independent of the heart size or wall thickness

A

Aortic impedance or elastance

43
Q

Estimated by the relationship between end-systolic LV pressure and SV

A

Arterial elastance

44
Q

An increase in heart rate progressively enhances the force of ventricular muscle contraction. This effect is known as?

A

Bowditch staircase phenomenon

Alternative name is treppe

45
Q

3 determinants of myocardial o2 demand

A

Preload
Afterload
Heart rate

46
Q

SBPxSVxHR = ?

A

Minute work

47
Q

External cardiac work can account for how many percent of myocardial o2 demand?

A

40%

48
Q

In patients with HFrEF what is the picture of the pressure-volume curve?

A

Shifted to the far right

ESVPR (end diastolic vol pres relationship) very shallow

49
Q

Occurs mid diastole when LA and LV pressure is almost equal. Contributes less than 5% of LV filling

A

Diastasis

50
Q

Atrial systole constitutes how many percent of LV diastolic filling?

A

15-25%

51
Q

Reflex that causes Increase in heart rate secondary to increase in CVP or return of blood to the atrium?

A

Bainbridge reflex

Cardio Quiz Bowl (6 decks)

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