cardiac cycle/heart sounds Flashcards

1
Q

driving force in cvs

A

heart

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2
Q

distribution vessels in cvs

A

arteries

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3
Q

exchange vessels in cvs

A

capillaries

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4
Q

reservoir for blood in cvs

A

veins

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5
Q

why is a cvs needed

A

diffusion slow over x >1mm

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6
Q

what does the SAN create

A

pacemaker potentials

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7
Q

Phase 0 of A/V AP’s

A

RAPID DEPOLARISATION:
vg NA channels
Na influx
VGCCs start to open slowly

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8
Q

Phase 1 of A/V AP’s

A

EARLY REPOLARISATION

Na channels close

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9
Q

Phase 2 of A/V AP’s

A

PLATEAU PHASE
VGCCs fully open - Ca influx
K channel starts to open slowly

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10
Q

Phase 3 of A/V AP’s

A

RAPID REPOLARISATION
VGCC channels close
K channels open fully - K EFFLUX

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11
Q

Phase 4 of A/V AP’s

A

RESTING PHASE
Normal action of Na-K pump
Membrane impermeable to Na
Membrane permeable to K

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12
Q

Where is electrical activity first generated

A

SAN

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13
Q

What does contraction of myocardium generate

A

pressure changes within chambers

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14
Q

valves open and close depending on what

A

pressure changes in chambers

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15
Q

blood flow from venous return to pulmonary circulation

A
SVC, IVC
RA
tricuspid
RV
pulmonary semilunar valve
pulmonary arteries
lung circulation
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16
Q

blood flow from pulmonary to systemic circulation

A
lung circulation
pulmonary veins 
LA
mitral valve
LV
Aortic semilunar valve
aorta
Systemic circulation
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17
Q

step 1 electrical conduction

A

electrical activity generated at SAN spreads out via gap junctions

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18
Q

step 2 electrical conduction

A

At AVN, conduction is delayed to allow correct filling of ventricles.

19
Q

step 3 electrical conduction

A

rapid conduction through bundle of His into ventricles

20
Q

step 4 electrical conduction

A

conduction through purkinje fibres spreads throughout ventricles - ventricular contraction begins at apex

21
Q

how long does systole last

A

0.34s

22
Q

how long does diastole last

A

0.66s

23
Q

cardiac cycle outline

A
  1. (v) diastole, atrial contraction
  2. ventricular isovolumetric contraction
  3. ventricular contraction and ejection / atrial filling
  4. ventricular isovolumetric relaxation
24
Q

Δchambers, volume in ventricular diastole

A

blood: atria > ventricles; pressure in atria > ventricles; AV valves open - aided by atrial systole

25
Q

Δchambers, volume in ventricular systole

A

pressure in full ventricles > atria; AV valves close; contraction increases pressure

26
Q

Δchambers, volume, in ejection

A

pressure in ventricles > aorta & pulmonary artery valves open, ejection; blood enters atria

27
Q

Δchambers, volume in ventricular diastole

A

pressure in pulmonary artery & aorta > ventricles;

aortic & pulmonary valves close

28
Q

define end diastolic volume

A

volume of blood in ventricles at end of diastole when the mitral valve is closed

29
Q

what is typical EDV

A

120ml

30
Q

typical end systole volume

A

40ml

31
Q

formula for ejection fraction

A

SV/EDV

(SV = EDV - ESV) =80ml

32
Q

normal value for ejection fraction -

A

2/3rd or more - lower values in heart failure

33
Q

a wave of atrial cycle

A

atrium contracting - tricuspid valvue open

34
Q

x descent of atrial cycle -

A

atrium relaxing then filling, tricuspid closed

35
Q

v wave of atrial cycle

A

atrium tense, full - tricuspid closed

36
Q

y descent of atrial cycle

A

atrium emptying, tricuspid open

37
Q

how is stroke work calculated

A

Δ in ventricular pressure * Δ in volume

38
Q

what does the area inside the ventricular pressure-volume loop represent

A

the amount of stroke work done - relates to ENERGY CONSUMPTION during cardiac cycle

39
Q

what causes heart sounds

A

vibrations caused by closure of cardiac valves; vibrations in ventricular chambers, turbulent flow of blood through veins

40
Q

what is S1/Lubb

A

closure of AV valves at start of ventricular systole

41
Q

what is S2/Dupp

A

closure of aortic/pulmonary valves at start of ventricular systole

42
Q

what is S3

A

occasional - turbulent flow into ventricles, detected near end of first third of diastole

43
Q

what is S4

A

pathological in adults - forceful atrial contraction against a stiff ventricle