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BRS 6: Cardiovascular And Respiratory Medicine > 6.5: Cardiac cycle > Flashcards

6.5: Cardiac cycle Flashcards

(51 cards)

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1
Q

Systole is

A

Contraction - ventricles generate pressure then eject blood into arteries

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2
Q

Diastole is

A

Relaxation - ventricles fill with blood

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3
Q

Each heart beat is split into two main phases

A

Diastole and systole

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4
Q

Diastole is split into how many phases

A

4 distinct phases

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5
Q

Systole is split into how many phases

A

3 distinct phases

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6
Q

7 stages of the cardiac cycle

A

Atrial systole (D)
Isovolumetric contraction (S)
Rapid ejection (S)
Slow ejection (S)
Isovolumetric relaxation (D)
Rapid passive filling (D)
Slow passive filling (D)

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7
Q

P wave on an ECG signifies

A

Start of atrial systole

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8
Q

In atrial systole

A

Atria are almost full from passive filling, driven by pressure gradient.
Atria contract to “top-up” volume of blood in ventricle

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9
Q

What 3 diseases can cause a 4th heart sound to arise (abnormal)

A

Congestive heart failure
Pulmonary embolism
Tricuspid incompetence

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10
Q

What does the QRS complex mark the start of

A

Ventricular depolarisation

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11
Q

During Isovolumetric contraction

A

[Contraction of ventricles with no change in volume (isometric)]
Interval between AV valves closing and semi-lunar valves opening

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12
Q

1st stage of cardiac cycle

A

Atrial systole

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13
Q

2nd stage of cardiac cycle

A

Isovolumetric contraction

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14
Q

Isovolumetric contraction produces

A

1st heart sound - ‘lub’ due to closure of AV valves and associated vibrations

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15
Q

What marks the start of the rapid ejection phase

A

Opening of the aortic and pulmonary veins

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16
Q

During the rapid ejection phase

A

Ventricles contact, pressure within them exceeds pressure in aorta and pulmonary arteries
Semilunar valves open, blood is pumped out and volumes of ventricles decrease - isotonic contraction
(No heart sounds)

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17
Q

3rd phase of the cardiac cycle

A

Rapid ejection

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18
Q

4th phase of cardiac cycle

A

Slow ejection / reduced ejection

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19
Q

5th phase of cardiac cycle

A

Isovolumetric relaxation

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20
Q

6th phase of cardiac cycle

A

Rapid passive filling

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21
Q

7th phase of cardiac cycle

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A

Slow passive filling

22
Q

Calculation for stroke volume

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A

End diastolic volume - end systolic volume = stroke volume (mL)

23
Q

Calculation for ejection fraction (%)

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A

100x (stroke volume / end diastolic volume ) = ejection fraction

24
Q

Reduced ejection marks

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A

The end of systole

25
During reduced ejection
Reduced pressure gradient means aortic and pulmonary valves being to close. Blood flow from ventricles decreases and ventricular volume decreases more slowly As pressure in ventricles fall below that in arteries, blood begins to flow back causing semilunar valves to close
26
What produces the T wave on an ECG
Ventricular muscle cells repolarizing - during reduced ejection
27
During Isovolumetric relaxation
Aortic and pulmonary valves shut, AV valves remain closed until ventricular pressure drops below atrial pressure. Atrial pressure continues to rise
28
What causes the Dichrotic notch on an ECG
Rebound pressure as distended aortic wall relaxes - Isovolumetric relaxation
29
What is the 2nd heart sound caused by
Closure of semi-lunar valves
30
Rapid passive filling on and ECG is represented by
Isoelectric (flat) between cardiac cycles
31
During rapid passive filling
Once AV valves open blood in the atria flows rapidly into ventricles
32
3rd heart sound can be due to
Usually abnormal May signify turbulent ventricular filling Can be due to hypertension or mitral incompetence
33
Reduced passive filling is also known as
Diastasis
34
During reduced passive filling
Ventricular volume fills more slowly Ventricles are able to fill considerably without the contraction of the atria
35
What are the patterns of pressure changes like in the right heart compared to the left
Identical in the right heart as in the left
36
Comparison of heart pressures quantitativley
Pressures in right heart and pulmonary circulation are much lower in the right heart but ejects same volume of blood as left
37
Pressures in the systemic circuit
High pressure 120/80 mmHg
38
Pressures in the pulmonary circuit
Low pressure 25/5 mmHg
39
Preload is determined by
Volume of blood returning to the heart (blood filling ventricles during diastole , stretching resting ventricular muscle)
40
Afterload is
Pressure heart has to work against
41
What is afterload determined by
Diastolic blood pressure (BP in great vessels - aorta, pulmonary artery)
42
What is preload
Stretch
43
What do Changes in preload and afterload affect
Shape of the PV loop
44
What does increased sympathetic stimulation result in
Increased cardiac myocyte [cAMP] Allows delivery of more Ca2+ to myofilaments
45
Delivery of more Ca2+ by increased sympathetic stimulation results in
Activation of sympathetic beta receptors by: Circulating catecholamines from adrenal gland Noradrenaline released from nerves
46
What affects the width of the PV loop
Changes in preload
47
What affects the height and left border of the PV loop
Changes in afterload Upper left point follows the ESPVR
48
What stimulation is present at rest
Parasympathetic
49
What happens to the heart rate at rest
Slowing of SA node due to parasympathetic stimulation From 110bpm to 70bpm
50
How does the sympathetic stimulation increase SA node rate (2)
Hormonal : circulating adrenaline from adrenal gland Neural : noradrenaline released from nerves
51
What is the longest phase of the cardiac cycle
TBA…

BRS 6: Cardiovascular And Respiratory Medicine (12 decks)

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