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BSI 2 > Lecture 14-15 > Flashcards

Lecture 14-15 Flashcards

1
Q

What is the mechanism by which valves open and close?

A

Valves open and close passively. Forward pressure gradient opens valves while backward pressure gradient closes valves.

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2
Q

Which valves have papillary muscle and chordae tendinae associated with them?

A

Atrioventricular valves (Tricuspid and Bicuspid valves)

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3
Q

What is the function of the chordae and tendinae?

A

Papillary muscle of AV valves prevent cusps from protruding into atria as ventricles contract

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4
Q

What are the 5 phases of the cardiac cycle?

A 
Atrial Contraction
Isovolumetric Contraction
Ventricular Ejection
Isovolumetric Relaxation
Ventricular filling
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5
Q

What happens to LEFT ventricular volume during each of the phases in the cardiac cycle?

A
  1. Atrial contraction - Volume is increased slightly due to atrial contraction.
  2. Period of isovolumetric contraction - Volume stays the same as the left ventricle contracts (~110ml)
  3. Period of ejection - volume is decreased as it ejects the blood out of the ventricle
  4. Period of isovolumetric relaxation - volume low (~40ml) but stays the same
  5. Ventricular filling - passive filling, volume steadily increases.
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6
Q

What happens to LEFT ventricular pressure during each of these phases?

A
  1. Atrial contraction - Pressure is slightly increased as atrial contraction forces blood in
  2. Period of isovolumetric contraction - pressure greatly increases
  3. Period of ejection - pressure continues to increase as it ejects the blood out of the ventricle and decreases halfway through ejection
  4. Period of isovolumetric relaxation - pressure continues to drop until it is below atrial pressure
  5. Ventricular filling - pressure is lower than atrial and steady
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7
Q

Describe when the mitral valve closes during the cardiac cycle. Specifically, what is causing the mitral valve to close?

A

Beginning of isovolumetric contraction is when it closes. Ventricle begins to contract- once pressure in ventricle exceed that of atrium, the AV valve will close.

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8
Q

Describe when the aortic valve opens during the cardiac cycle. Specifically, what is causing the aortic valve to open?

A

Period of ejection; The aortic valve opens when the pressure in the ventricle exceeds that of the aorta (arterial pressure) after Isovolumetric contraction.

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9
Q

Describe when the aortic valve closes during the cardiac cycle. Specifically, what is causing the aortic valve to close?

A

As pressure drops during period of ejection, ventricular pressure falls below arterial pressure which will cause the aortic valve will close.

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10
Q

Does atrial contraction force the AV valves to open?

A

No, during isovolumetric relaxation, the ventricle pressure will drop below that of the atrium and therefore the AV valve opens leading to the ventricular filling phase.

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11
Q

How does an increase in venous return affect preload of the left ventricle?

A

More volume entering will create more preload, which causes more stretching, which would create more contraction force.

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12
Q

How does aortic pressure affect afterload of the left ventricle?

A

The afterload has to be greater than that of the aortic pressure in order to eject blood from the ventricle.

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13
Q

If preload and contractility both affect the strength of contraction, what is the difference between them?

A

Preload is dependent on stretch and contractility is dependent on the strength of myocardial contraction, such as increase in Ca2+ concentration in cardio myocytes would increase their contractile force.

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14
Q

What is systole?

A

Contraction phase of cardiac cycle.

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15
Q

What is Systolic blood pressure (SBP)?

A

The pressure in the systemic arteries (aorta) while the left ventricle is contracting and ejecting blood (120 mmHg)

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16
Q

What is Diastole?

A

Relaxation phase of cardiac cycle

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17
Q

What is Diastolic blood pressure (DBP)?

A

The pressure in the systemic arteries (aorta) while the left ventricle is relaxing and not ejecting blood (80 mmHg)

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18
Q

What is End diastolic volume (EDV)?

A

The volume of blood in the ventricle at the end of diastole (110 ml), in other words, the amount of blood in the ventricle once it is filled just before it contracts.

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19
Q

What is Pulse pressure?

A

Pulse pressure is the difference between the systolic and diastolic pressures (SBP-DBP= pulse pressure)

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20
Q

_____ _____ is an important determinant of EDV.

A

Venous return

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21
Q

What is End systolic volume (ESV)?

A

The volume of blood in the ventricle at the end of systole (40 ml)

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22
Q

What is Stroke volume (SV)?

A

The volume of blood pumped out of the ventricle per contraction (70 ml)
Determined by preload, afterload, and contractility.
(SV = EDV-ESV)

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23
Q

What is Ejection fraction?

A

The fraction of EDV that was pumped out of the left ventricle per contraction (60%)
(SV/EDV x 100= EF)

24
Q

What is Cardiac output (CO, Q)?

A

The amount of blood pumped out of the left ventricle per minute.
(Cardiac output = heart rate x stroke volume (5000 ml))

25
Q

What is Venous return?

A

The amount of blood returned to the heart.

26
Q

What is Preload?

A
  1. The pressure stretching the chamber of the heart before it contracts
  2. As the muscle stretches, the stretching induces length-dependent activation of the contractile apparatus leading to greater strength of contraction
  3. In other words, preload is the stretched state of the ventricle before it contracts; the greater the stretch, the greater the preload… so when it contracts it will contract with greater force.
27
Q

Preload is determined primarily by _____.

A

EDV

28
Q

What is afterload?

A

The pressure that the chamber of the heart has to overcome in order to eject blood.

29
Q

________ pressure is an important determinant of the afterload of the left ventricle.

A

Aortic

30
Q

_________ pressure is an important determinant of the afterload of the right ventricle.

A

Pulmonary

31
Q

As aortic pressure (arterial pressure) increases, the _______ of the left ventricle increases.

A

afterload

32
Q

What is Contractility (Inotropy)?

A

The intrinsic ability of cardiac muscle to produce tension, independent of fiber (sarcomere) length. A change in the force of contraction at a constant end-diastolic fiber length reflects a change in contractility (anything that affects excitation-contraction, other than sarcomere/fiber length, affects contractility)

33
Q

________ _________ concentration is an important determinant of contractility.

A

Intracellular Ca2+; Under normal physiological conditions, it is primarily the changing intracellular Ca2+ that will alter contractility throughout the day.

34
Q

Anything that stimulates an increase in intracellular Ca2+ concentration in ______, such as, norepinephrine (SNS) will increase contractility.

A

cardiomyocytes

35
Q

___________ is dependent on stretch and ______ is not dependent on stretch.

A

Preload ; contractility

36
Q

Chronotropic effect affects the _________.

A

heartrate

37
Q

Inotropic effect affects _______.

A

contractility

38
Q

What is cardiac reserve?

A

The work that the heart is able to perform beyond that required of it under basal/resting conditions (300-400%)

39
Q

What is Pressure-Rate Product or Double Product?

A

An indirect index of myocardial O2 consumption (how hard the ventricle is working). (HR x SBP (or MAP))

40
Q

T or F? The heart can function without atrial contraction.

A

True. The atria functions to enhance the amount of blood in ventricles, which enhances ventricular pumping.

41
Q

T or F? The ventricles pump blood through pulmonary circulation (left) and systemic circulation (right).

A

False, pulmonary circulation (RIGHT) and systemic circulation (LEFT)

42
Q

Which phase of the CC is described? “AV valve is open; atrium pumps blood into ventricle”

A

Atrial contraction

43
Q

Which phase of the CC is described? “Ventricle begins to contract- once pressure in ventricle exceed that of atrium, the AV valve will close.”

A

Isovolumetric Contraction

44
Q

Which phase of the CC is described? “Ventricular pressure rises above arterial pressure, semilunar valve opens”

A

Period of Ejection

45
Q

Which phase of the CC is described? “Ventricle begin to relax; pressure begins to drop within ventricle, as pressure drops below arterial pressure, semilunar valve closes”

A

Isovolumetric relaxation

46
Q

Which phase of the CC is described? “Passive filling of ventricle”

A

Ventricular filling

47
Q

Active ventricular filling occurs in which phase of the cardiac cycle?

A

Atrial contraction. (Passive filling is the ventricular filling phase)

48
Q

Closing of the AV valves can be heard in which heart sound classification?

A

S1

49
Q

Closing of the semilunar valves can be heard in which heart sound classification?

A

S2

50
Q

What is the “lub dub” sound of the heart?

A

S1 (closing of AV valves) and S2 (closing of SV valves)

51
Q

T or F? Presence of S3 and/or S4 may be indicative of an abnormality.

A

True

52
Q

____ is thought to be caused by the oscillation of blood back and forth between the walls of the ventricles initiated by inrushing blood from the atria (increased volume of blood within the ventricle; may be associated with ventricular dilation)

A

S3 (heart sound)

53
Q

____ may be heard during atrial contraction; may be heard when atrial pressure is high or ventricle is stiff.

A

S4 (heart sound). (example: S4 may be heard if there is ventricular hypertrophy; hypertrophy causes stiffening of the ventricle)

54
Q

What is the C-wave on the left atrial pressure graph?

A

It is the pressure in the atrium caused by the shared wall when the ventricle contracts.

55
Q

What is the dicrotic wave?

A

During isovolumetric relaxation, when the aortic valve slams shut, the slight pressure results from the blood slamming against the aortic valve.

BSI 2 (22 decks)

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