Cardiovascular L3: The Cardiac cycle & Heart sounds Flashcards by Vanessa Chuah

The cardiac cycle is the period between _______ and the next

one heartbeat

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How is the pattern of the cardiac cycle defined?

Valves

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What are the functions of valves?

Makes sure that when the heart contracts, blood only goes in one direction and can’t flow back

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In each cycle, the atria and ventricles undergo separate phases of ______ and ________.

systole (contraction); diastole (relaxation)

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To ensure forward blood flow and prevent backwards flow, the heart has two sets of valves: ________ and _________.

atrioventricular (AV; tricuspid & mitral); semilunar valves (aortic and pulmonary)

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When will a valve open?

A valve will open if the pressure behind it is greater than the pressure in front of it

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A valve will open if the pressure behind it is ______ (greater/lower) than the pressure in front of it, and close if pressure behind is _____ (greater/lower)

greater; lower

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When will a valve close?

If pressure behind is lower

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Where are the 4 major valves located?

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What does a tricuspid valve mean/look like?

3 parts

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What does a bicuspid or ‘mitral’ valve look like?

2 parts

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What does an aortic or pulmonary valve look like?

semilunar valves

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Heart valves only open in one direction. True or false. Why?

True- can’t open backwards- chordae tendinae (helps)

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What are 2 problems/damage with the valves?

Stenosis (not opening properly)
Regurgitation (can’t close properly)

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What are the 4 phases within the cardiac cycle?

Ventricular diastole: ventricles fill with blood
Isovolumetric ventricular contraction: ventricles contract, all four valves are closed, pressure rises
Ventricular ejection: pressure forces blood past the semilunar valves
Isovolumetric ventricular relaxation: pressure falls, initially isovolumetric, but then AV valves open and filling begins again

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What happens when combining electrical, pressure and volumetric components of cradiac cycle?

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What are the 9 steps of the left ventricular pressure-volume loop?

The AV valve opens
Passive ventricular filling occurs Big increase in volume, but slight increase in pressure
Atrial contraction completes ventricular filling. End-diastolic volume is reached
The AV valve closes
Isovolumetric ventricular contraction occurs. Volume remains constant; pressure increases markedly
The aortic valve opens
Stroke volume ejected. Endsystolic volume is reached
The aortic valve closes
Isovolumetric ventricular relaxation occurs. Volume constant; pressure falls sharply

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What is stroke volume?

Volume that is actually ejected

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What is the end-diastolic volume (EDV)?

is the volume of blood inthe ventricle when filling is complete (aka ‘preload’)

What is the end-systolic volume (EDV)?

is the volume of blood remaining in the ventricle when ejection is complete

What is the stroke volume (SV)?

is the volume of blood pumped out by each ventricle per beat (EDV-ESV)

What is the ejection fraction (EF)?

is the proportion of EDV pumped out in each heartbeat calculated as: SV/EDV x 100, or 70ml/135ml x 100 = 52%

How big volume is compared to how much is left behind

What is afterload?

is the pressure against which the heart must work to eject blood during systole (also defined as the stress on the ventricular wall during systole) (pressure around arteries)

If a faster heart rate reduces filling time, how do we still get good stroke volume?

Passive filling occurs rapidly early in diastole, then slows, with extra boost from atrial contraction

Systole = no change with increased HR Increased HR = decreased diastole = fill ventricles less but does not change volume due to atrial contraction = can still continue to fill heart well even with increase HR

However, there is an end point (max. HR) at ~ 20bpm

What does the sound of turbulence of the blood make?

Lub-dub

Valve closure produces ___ normal heart sounds

What are the 2 normal heart sounds?

1. The first heart sound (S1) or ‘lub’ is caused by closing of the AV valves 2. The second heart sound (S2) or ‘dub’ is caused by closing of the aortic and pulmonary valves Important to know: not the sounds of valves closing that you hear

To hear blood, it must be \_\_\_\_\_\_. Why?

tubulent * When the valves close blood bounces against them, creating turbulence, which you can hear

When do the valves close?

* Both left &right AV valves close at the beginning of systole = S1 (‘lub’) * Aortic & pulmonary valves close at the end of systole = S2 (‘dub’) * Opening of the valves does not cause any sound

Valves don't shut at the same time. True or false.

False valves should shit at same time

What occurs in the pathological condition of pulmonary hypertension? What is heard that is unusual?

Increased pressure in pulmonary system = valves will close sooner than normal = splitting of the heart sound = doubling of sound

What are 2 other heart sounds that can be heard? (not lub or dub)

1. The third heart sound (S3) marks end of rapid filling phase in early diastole, and is due to “recoil” of blood from ventricular wall 2. The fourth heart sound (S4) coincides with atrial contraction (late diastole), it is not normally heard, but can indicate pathology involving strong atrial contraction

What are heart murmurs? What do you hear in hearts that have pathology?

Healthy valves appose their edges efficiently, but several diseases, including bacterial infections and congenital malformations, may deform valves, affecting their opening and/or closing Failure of valves to close or open properly creates abnormal turbulence: Heart murmurs * Regurgitation or insufficiency - when valves cannot close tightly, blood flows through the resulting gaps in wrong direction * Stenosis - when the passages containing valves decrease in size, blood flow in the correct direction is impeded

Failure of valves to close or open properly creates abnormal turbulence. These are called \_\_\_\_\_\_\_.

Heart murmurs

What is regurgitation or insufficiency?

when valves cannot close tightly, blood flows through the resulting gaps in wrong direction

What is stenosis?

when the passages containing valves decrease in size, blood flow in the correct direction is impeded

Can the type and timing of murmurs can indicate type of pathology?

Yes

What sound does a heart with aortic stenosis make?

‘Lub-whistle-dub’ Aortic valve hasn't shut properly

What sound does a heart with mitral reguritation make?

‘Lub-swish-dub’

What sound does a heart with aortic regurgitation make?

‘Lub-dub-swish'

What sound does a heart with mitrial stenosis make?

‘Lub-dub-whistle’

What sound does a heart with patent ductus arteriosus make?

‘whistle’ throughout Hole in the heart between the aorta and the pulmonary artery

What is the anatomical basis of patent ductus arteriosus (in a fetus and in an adult? Why is it normal in a fetus and not in an adult? What does it cause in an adult?

Fetus- no oxygenated blood Adult- hole in septum doesn't close when born --\> oxygenated blood back into pulmonary artery --\> decrease blood to rest of body

What is auscultation?

Listening to the heart

What structure stops valve flaps from turning inside out?

Chordae tendinae