cardiac cycle/heart sounds

Question 1

driving force in cvs

Answer 1

heart

Question 2

distribution vessels in cvs

Answer 2

arteries

Question 3

exchange vessels in cvs

Answer 3

capillaries

Question 4

reservoir for blood in cvs

Answer 4

veins

Question 5

why is a cvs needed

Answer 5

diffusion slow over x >1mm

Question 6

what does the SAN create

Answer 6

pacemaker potentials

Question 7

Phase 0 of A/V AP’s

Answer 7

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

Question 8

Phase 1 of A/V AP’s

Answer 8

EARLY REPOLARISATION

Na channels close

Question 9

Phase 2 of A/V AP’s

Answer 9

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

Question 10

Phase 3 of A/V AP’s

Answer 10

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

Question 11

Phase 4 of A/V AP’s

Answer 11

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

Question 12

Where is electrical activity first generated

Answer 12

SAN

Question 13

What does contraction of myocardium generate

Answer 13

pressure changes within chambers

Question 14

valves open and close depending on what

Answer 14

pressure changes in chambers

Question 15

blood flow from venous return to pulmonary circulation

Answer 15

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

Question 16

blood flow from pulmonary to systemic circulation

Answer 16

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

Question 17

step 1 electrical conduction

Answer 17

electrical activity generated at SAN spreads out via gap junctions

Question 18

step 2 electrical conduction

Answer 18

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

Question 19

step 3 electrical conduction

Answer 19

rapid conduction through bundle of His into ventricles

Question 20

step 4 electrical conduction

Answer 20

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

Question 21

how long does systole last

Answer 21

0.34s

Question 22

how long does diastole last

Answer 22

0.66s

Question 23

cardiac cycle outline

Answer 23

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

Question 24

Δchambers, volume in ventricular diastole

Answer 24

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

Question 25

Δchambers, volume in ventricular systole

Answer 25

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

Question 26

Δchambers, volume, in ejection

Answer 26

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

Question 27

Δchambers, volume in ventricular diastole

Answer 27

pressure in pulmonary artery & aorta > ventricles; | aortic & pulmonary valves close

Question 28

define end diastolic volume

Answer 28

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

Question 29

what is typical EDV

Answer 29

120ml

Question 30

typical end systole volume

Answer 30

40ml

Question 31

formula for ejection fraction

Answer 31

SV/EDV (SV = EDV - ESV) =80ml

Question 32

normal value for ejection fraction -

Answer 32

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

Question 33

a wave of atrial cycle

Answer 33

atrium contracting - tricuspid valvue open

Question 34

x descent of atrial cycle -

Answer 34

atrium relaxing then filling, tricuspid closed

Question 35

v wave of atrial cycle

Answer 35

atrium tense, full - tricuspid closed

Question 36

y descent of atrial cycle

Answer 36

atrium emptying, tricuspid open

Question 37

how is stroke work calculated

Answer 37

Δ in ventricular pressure * Δ in volume

Question 38

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

Answer 38

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

Question 39

what causes heart sounds

Answer 39

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

Question 40

what is S1/Lubb

Answer 40

closure of AV valves at start of ventricular systole

Question 41

what is S2/Dupp

Answer 41

closure of aortic/pulmonary valves at start of ventricular systole

Question 42

what is S3

Answer 42

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

Question 43

what is S4

Answer 43

pathological in adults - forceful atrial contraction against a stiff ventricle