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PHYSIO EXAM 2 > L19/20 Cardiac Cycle > Flashcards

L19/20 Cardiac Cycle Flashcards

1
Q

Cardiac cycle

A

Systole
Generation of pressure by heart
Contraction of a chamber
Ejection of blood from a chamber

Diastole
Period of relaxation of heart
Filling of chambers with blood
Perfusion of coronary arteries

Systole + diastole = cardiac cycle

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2
Q

Components of cardiac cycle

A

Pressures within chambers and vessels (left atria, ventricle and aorta)

Sounds (valve closure and filling: S1 - S4)

Volumes of blood within chambers and vessels

Venous pulses (a,c, and v waves) (changes of pulse in jugular vein)

Events of EKG (P, QRS, T)

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3
Q

Phases of cardiac cycle

A-G

A 
A: atrial systole 
B: isovolumic ventricular contraction
C: rapid ventricular ejection 
D: reduced ventricular ejection 
E: isovolumic ventricular relaxation 
F: rapid ventricular filling 
G: reduced ventricular filling
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4
Q

How is direction of blood flow through heart established?

A

Mechanical valves

Atrioventricular (AV) valves

Semilunar (SL) valves (aortic and pulmonary)

Opening and closing of valves is PASSIVE due to differences in blood pressure across the valves

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5
Q

How do AV valves work during ventricular diastole?

A

Pressure in atrium > pressure in ventricle

Pressure difference keeps both AV valves OPEN

ventricle fills 80% before atria contract

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6
Q

How does AV valve work during ventricular systole?

A

Pressure in ventricle > pressure in atrium

Pressure difference CLOSES AV valve

Prevents backflow
Blood leaves ventricle via aortic or pulmonary valve
Heart “lub” heard , 1st sound

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7
Q

How do seminlunar valves work during ventricular diastole?

A

P vessel (aorta or pulmonary) > P ventricle

P difference keeps aortic and pulmonary valves CLOSED

Prevents backflow

At very beginning: P ventricle drops suddenly, semilunar valve snaps shut, heart “dup” heard

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8
Q

How do seminlunar valves work during ventricular systole?

A

P ventricle > P vessels

P difference OPENS semilunar valve

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9
Q

Changes in pressure is when

A

Valves open and close

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10
Q

A
Atrial systole
AV valve opens; SL valve closes

A

P wave initiates atrial contraction
Pressure increases
Pressure gradient across AV valves
Causes rapid flow of blood into ventricles

Produces increase in venous pressure noted by a-wave of jugular pulse

Accounts for 10-25% of ventricular filling (most is passive before contraction) during exercise, higher HR, may account for 40% filling

4th heart sound heard (vibration of ventricular wall) will be more pronounced when ventricular compliance is reduced/ LV hypertrophy

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11
Q

Atrial systole

A

After contraction atrial pressure begins to fall and causes AV valves to float upward/close

Ventricular volumes of blood MAXIMAL = end-diastolic volume ( end of relaxation for the ventricular) normally 120mL
Is ventricular preload pressure

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12
Q

B
Isovolumic contraction
All valves closed

A

Contraction of ventricles

Initiated by QRS complex
Depolarization lead to a rapid pressure increase

This causes AV valves to close = vibrations produce 1st heart sound (S1) “lub”

S1 split noted because mitral valve closes before tricuspid

During time btw closure of AV valve and opening of SL/aorta- pressure rises w/out volume change and no ejection occurs

Atrial pressure rises
W/ bulging of AV valve into atria chambers
c wave noted in jugular pulse

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13
Q

C
Rapid ejection
SL valves open; AV valves remain open

A

When intraventricular pressures exceed pressures within aorta/pulmonary artery - valves open and blood is ejected

Maximal outflow velocity is reached
Most stroke volume ejected
Dramatic decrease in ventricular volume

Maximal systolic (aortic) and pulmonary artery pressure are achieved

Ventricular pressure exceeds vessel by a few mmHg
At very end and atrial filling begins from vena cava and pulmonary vein causing atrial pressure to rise (ejected next cycle)

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14
Q

D
Reduced ejection
SL valves open; AV valves remain closed

A

After QRS complex- ventricles begin to repolarize (T wave)

Ventricles no longer contracting and their pressure falls (SL valves still open)

Blood continues to eject due to inertial energy of blood

Volume of ventricles reaches minimum

Pulmonary/aortic pressures falls as blood is running off into arterial tree

Atrial pressure continues to rise due to venous return

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15
Q

E
Isovolumic ventricular relaxation
All valves closed

A

Begins after all ventricles fully repolarized

Ventricles relaxed and compliant
Pressure declines dramatically
Pressure drops below vessel pressure, closing aortic/pulmonary valves and produce 2nd sound S2 “dub” that’s spilt into A and P (dicrotic botch)

Ventricular volume at lowest and remains constant - end-systolic volume (~50mL)

Atrial pressure continues to rise due to venous return

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16
Q

F
Rapid ventricular filling
AV valves open; SL valves closed

A

Ventricular P falls below atrial - AV valve opens, ventricular filling begins

Atrial pressure falls- peak of jugular pulse is right before AV valve opens (v-wave)

LV pressure remains low because ventricle is compliant and relaxed

Healthy AV - no sounds during filling
Unhealthy/ children - 3rd sound heard (tensing of chorded tendineae and AV valve ring)

17
Q

G
Reduced ventricular filling
AC valves open; SL valves closed

A

Final portion of passive ventricular filling

Continue to fill and expand become less compliant

Intraventricular pressure increases, reducing pressure gradient across AV valves (rate of filling falls)

Longest phase of cardiac cycle

Increases in HR decreases time for this phase
Reduces or eliminates ventricular filling
Decreases ventricular filling
Reducing preload and stroke volume

18
Q

Stroke volume

A

volume if blood ejected on ventricular contraction

Difference in EDV and ESV

SV=EDV-ESV (mL/beat)

~70mL

Consistent part = edv
Lowest part = esv

19
Q

Right vs left cardiac cycle differences

A

Magnitudes of peak systolic pressures in both ventricles (left much higher)

Systole of LV occurs before RV systole

Mitral valve closes before tricuspid

Aortic valve closes before pulmonary

20
Q

Function of ventricle is described by?

A

Stroke volume
Ejection fraction
Cardiac output
Cardiac index

21
Q

Ejection fraction

A

Effectiveness of ventricles in ejecting blood

Fraction of the EDV that is ejected in one stroke volume

Indicator of contractility

EF=SV/EDV x 100%

22
Q

Cardiac output

A

CO

Totally volume of blood ejected per into time

Product of SV and HR

CO= HR x SV

one for R and L
R - 100% goes to lungs
L- to diff vascular beds

23
Q

Cardiac index

A

CI

CO normalized for surface area (SA)

CI=CO/SA

24
Q

S1

A

Caused by closure of AV valves during isovolumic contraction

25
Q

S2

A

Caused by closure of SL valves during isovolumic relaxation

Two audible components
Aortic A2
Pulmonic P2

Inspiration causes spilling

26
Q

S3

A

Not common

Occurs during rapid ventricular filling

Heard in children not normal in adults

27
Q

S4

A

Heard during atrial systole (end diastole) where ventricular compliance is decreased

Not very loud unless ventricular hypertrophy

28
Q

S2 split during isovolumic relaxation

A

Aortic closes before pulmonary

Splits into 2 sounds A2 and P2

Inspiration increases the spilt
Expiration decrease the spilt

Changes in spilt can be associated with pathological conditions

29
Q

Inspiration increasing split of S2

A

Delays closure of pulmonic valve after aortic valve has closed

Decreases intrathoracic pressures
Increases venous return to RIGHT ventricle
Increase preload and SV
prolongs RIGHT ventricular ejection time
Delays closure of pulmonic valve

30
Q

Pathological conditions that widen S2 split

A

Pulmonic stenosis ( narrowing of pulmonary valve)

Right ventricular failure (will increase preload)

Right bundle branch block (delays depolarization)

31
Q

Pathological conditions that narrow S2 split

A

Left bundle branch block

32
Q

Paradoxical splits pathology

A

P2 heard before A2

Severe aortic stenosis

33
Q

Murmur

A

Originate from abnormal movement of blood across valves and between cardiac chambers

Turbulence results producing vibrations

Distinct from heart sounds that represent closure of valves during cardiac cycle

34
Q

Systolic murmurs

A

Occur during ventricular systole or after S1 but before S2

Associated with ejection of blood through damaged valves
Aortic or pulmonary valve stenosis (opening narrowed)
Mitral or tricuspid regurgitation (incomplete closure/incompetent valves) blood forced back into atrium

35
Q

Types of systolic murmurs

A

Mid-systolic

Holosystolic / pansystolic mumur

36
Q

Mid-systolic murmur

A

Crescendo-decrescendo character

Caused by aortic or pulmonary valve stenosis

Starts soft and build to maximum and decreases again

37
Q

Holosystolic / pansytolic murmur

A

Consistent sounds heard

Associated with AV valve regurgitation

38
Q

Diastolic murmur

A

While ventricle relaxed

Occurs after S2

Associated with valvular issues during ventricular relaxation and filling

Aortic regurgitation
Pulmonic valve regurgitation
Mitral or tricuspid valve stenosis

PHYSIO EXAM 2 (5 decks)

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