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Physiology 1 > L19&20 Cardiac Cycle > Flashcards

L19&20 Cardiac Cycle Flashcards

1
Q

What are the phases of the cardiac cycle in order?

A 
Atrial systole
Isovolumic ventricular contraction
Rapid ventricular ejection
Reduced ventricular ejection
Isovolumic ventricular relaxation
Rapid ventricular filling
Reduced ventricular filling
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2
Q

What is systole?

A

Generation of pressure by the heart, contraction of a chamber, and ejection of blood from a chamber

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3
Q

How do AV valves work during ventricular diastole?

A

The pressure in the atrium is greater than in the ventricle and this keeps both the AV valves open.
-80% of the ventricular filling occurs before atrial contract

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4
Q

How do the AV valves work during ventricular systole?

A

Pressure in the ventricle is greater than pressure in atrium, which closes the AV valves.
-Prevents backflow and blood leaves ventricle via aortic or pulmonary valve

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5
Q

What is the first heart sound “lub”?

A

Ventricular systole when the AV valves close

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6
Q

How do the semilunar valves work during ventricular diastole?

A

Pressure in the aorta/pulmonary valves are greater than the pressure in the ventricle.
Pressure difference keeps aorta and pulmonary valves closed to prevent backflow

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7
Q

What valves are open during atrial systole?

A

AV valves are open, SL valves are closed

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8
Q

Atrial contraction accounts for how much of ventricular filling?

A

10-25%

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9
Q

What heart sound is atrial contraction?

A

4th sound, S4. Caused by vibration of ventricular wall.

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10
Q

What is isovolumic contraction?

A

The time period between closure of the AV valves and the opening of SL valves

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11
Q

What is the rapid ejection phase?

A

When intraventricular pressure exceeds pressures within the aorta and pulmonary artery, valves open and blood is ejected

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12
Q

What valves are open during rapid ejection?

A

SL valves open and AV valves remain closed

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13
Q

When is maximal systolic and pulmonary pressures achieved?

A

Rapid ejection

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14
Q

When does atrial filling from the vena cava start occurring?

A

The rapid ejection phase (of the ventricles), causing atrial pressure to rise. This blood will be ejected in the next cycle

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15
Q

What is the reduced ejection phase?

A

When ventricular pressure falls because ventricles are no longer contracting, however SL valves ares still open and blood continues to be ejected due to initial energy of blood

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16
Q

What valves are open during reduced ejection?

A

SL valves open and AV remains closed

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17
Q

Reduced ejection is marked by what wave?

A

T wave

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18
Q

What is isovolumic relaxation?

A

Begins when the ventricles are fully repolarized, ventricles relax and become compliant.
-Pressure declines dramatically and valve closure is associated a dicrotic notch

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19
Q

What produces the second heart sound “dub”?

A

When ventricular pressure drops below vessel pressure, the SL valves close (split into A2 and P2)

20
Q

What is end systolic volume?

A

When ventricular blood is at its lowest during isovolumic relaxation and this amount of blood is the ESV
-Roughly ~50 ml

21
Q

What is stroke volume?

A

Difference between EDV and ESV

-Roughly ~70ml

22
Q

What is rapid ventricular filling?

A

Ventricular pressure falls below atrial pressure, AV valves open, and ventricular begins filling.
-Opening of AV valves causes a fall in atrial pressure

23
Q

What is the V wave?

A

During rapid ventricular filling, peak of jugular pulse just before AV valves open

24
Q

If a heart sound is heard during rapid ventricular filling, What could it indicate?

A

It may indicate tensing of chordae tendinae and AV valve ring -3rd sound (s3)

  • Normal in kids
  • Pathological in adults and caused by ventricular dilation
25
Q

What is reduced ventricular filling?

A

The final portion of the passive ventricular filling, ventricles continue to fill with blood and expand (they become less compliant)
-Ventricular pressure increases , Redding pressure gradient across the AV valves

26
Q

What is the longest phase of the cardiac cycle?

A

Reduced ventricular filling

27
Q

What are the 4 things that describe the function or efficiency of the ventricle?

A
  • Stroke volume
  • ejection fraction
  • cardiac output
  • cardiac index
28
Q

What is stroke volume?

A

Volume of blood ejected on one ventricular contraction.

-The difference between the volume of blood in the ventricle at the end of atrial systole and following reduced ejection

29
Q

What is the ejection fraction?

A

Fraction of the end diastolic volume that is ejected in one stroke volume
-The effectiveness of the ventricles in ejecting blood

30
Q

What is the calculation for Ejection fraction?

A

EF= SV/EDV x100%

31
Q

What is cardiac output?

A

Total volume of blood ejected per unit of time.

-Product of stroke volume and HR

32
Q

What is the calculation for Cardiac output (CO)?

A

CO= HR x SV

33
Q

What is cardiac index?

A

The cardiac output normalized for body surface area (SA)

34
Q

What is the formula for calculating cardiac index?

A

CI= CO/SA

35
Q

What is the S2 split?

A

During normal isovolumic relaxation, the aortic valve closes before the pulmonary valve. S2 splits into two sounds, A2 and P2. A2 occurs first

36
Q

What effect does inspiration have on the S2 split?

A

It increases the A2-P2 split

37
Q

What effect does expiration have on the S2 split?

A

Expiration decreases the A2-P2 split

38
Q

What are pathological conditions that can widen the S2 split?

A
  • Pulmonic stenosis
  • Right ventricular failure
  • RBBB
39
Q

What pathology can cause the S2 split to narrow or disappear?

A

LBBB

40
Q

What can cause a paradoxical split to occur (P2 is heard before A2?)

A

Severe aortic stenosis

41
Q

When do systolic murmurs occur?

A

Ventricular systole or after S1 (but before S2)

42
Q

What are systolic murmurs often associated with?

A

Aortic stenosis or mitral or tricuspid regurgitation

43
Q

What are mid-systolic murmurs?

A

Crescendo-decrescendo character, caused by aortic or pulmonary valve stenosis

44
Q

What are holosystolic (pansystolic) murmurs caused by?

A

Associated with AV valve regurgitation

45
Q

When do diastolic murmurs occur?

A

after S2

46
Q

What are diastolic murmurs associated with?

A

Valvular issues during ventricular relaxation and filling

  • aortic regurgitation
  • pulmonic valve regurgitation
  • mitral or tricuspid valve stenosis

Physiology 1 (6 decks)

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