The Heart As A Pump

Question 1

Systole

Answer 1

Contraction and ejection of blood from ventricles

Question 2

Diastole

Answer 2

Relaxation and filling of ventricles

Question 3

What do atria act as

Answer 3

Priming pumps for ventricles

Question 4

Pressures in circulation system

Answer 4

Pulmonary - low pressure

Systemic - high pressure

Question 5

Journey of blood (if followed one cell)

Answer 5

Vena cava (inferior or superior)
Right atrium 
Tricuspid valve
Right ventricle
Pulmonary valve 
Pulmonary artery 

Pulmonary vein
Left atrium 
Mitral valve 
Left ventricle 
Aortic valve
Aorta 
Aorta

Question 6

Stroke volume and typical values

Answer 6

Volume of blood ejected per beat

70ml per beat = 4.9 litres per minute

Question 7

Typical blood volume

Answer 7

5L

Question 8

What makes heart muscle?

Answer 8

Specialised cardiac myocytes

Discrete cells but connected

Question 9

When do myocytes contract?

Answer 9

Action potential and depolarisation = contraction

Action potential causes rise in intracellular calcium

Question 10

Cardiac action potential length

Answer 10

LONG (280ms) - allows spread so heart can contract in syncytium

Question 11

Heart valves

Answer 11

Right: tricuspid and pulmonary
Left mitral and aortic

Open or close depending on pressure

Question 12

How are cusps of valves assisted?

Answer 12

Papillary muscles attach to chordae tendineae to prevent inversion of valves during systole

Question 13

Conduction system of heart

Answer 13

Pacemaker cells sinoatrial node
Spreads over atria (atria systole)
Atrioventricular node - then delayed
Spreads down septum of ventricles
Spreads from inner to outer myocardium 
Ventricles contract from apex upward

Question 14

7 phases of cardiac cycle

After I RRelease I RRefill

Answer 14

Atrial contraction 
Isovolumetric contraction 
Rapid ejection
Reduced ejection
Isovolumetric relaxation 
Rapid filling 
Reduced filling

Question 15

Systole typical length (67 beats per minute HR)

Answer 15

0.35s

Question 16

Diastole typical length

Answer 16

0.55s

Question 17

Duration of cardiac cycle typically

Answer 17

0.9s

Question 18

What happens to cardiac cycle when exercising or if heart rate increases?

Answer 18

Diastole is reduced, systole stays the same

Question 19

What creates S1 and S2

Answer 19

S1 - closing of tricuspid and mitral valve

S2 - closing of aortic and pulmonary valve

Question 20

Phase 1 - atrial contraction features

Answer 20

Atrial pressure rises (A wave in atrial pressure)

Only fills ventricles up with last 10% of blood

P wave electrocardiography = atrial depolarisation

Ventricle volume maximum (EDV)

Question 21

Phase 2 - Isovolumetric contraction

Answer 21

S1: Mitral valve closes - ventricle pressure exceeds atrial
Closing of valve causes C wave (atrial pressure briefly increases)
Rapid rise in ventricular pressure
QRS ECG = ventricular depolarisation

Question 22

Phase 3 - rapid ejection

Answer 22

Aortic valve opens - ventricular pressure exceeds aortic
X descent atria - pulled downwards as ventricles contract
Rapid decrease in ventricular volume

Question 23

Phase 4 - reduced ejection

Answer 23

Repolarisation of ventricles = less tension so rate of ejection falls
Atrial pressure rises due to venous return
T wave ECG = ventricular repolarisation

Question 24

Phase 5 - Isovolumetric relaxation

Answer 24

S2 aortic valve closes
Dicrotic notch in aortic pressure from valve closure
Volume same (ALL VALVES CLOSED)
Ventricles at ESV - empty as they get

Question 25

Phase 6 - rapid filling

Answer 25

Y descent - mitral valve opens (atrial) Mitral valve opens when ventricle pressure falls below atrial Rapid ventricular filling occurs (S3)

Question 26

S3

Answer 26

Normal in children Ventricular filling Sign of pathology in adults

Question 27

Phase 7 - reduced filling

Answer 27

Rate of filling slows as ventricles reach relaxed volume 90% filled (Atrial contraction provides last 10% in phase 1)

Question 28

Abnormal valve functions

Answer 28

Stenosis - valve doesn’t open enough, obstruction of blood flow Regurgitation - valve doesn’t close all the way, back leakage

Question 29

Aortic valve stenosis causes

Answer 29

Degenerative (fibrosis/calcification) Congenital (bicuspid instead of tri) Chronic rheumatic fever - autoantibodies attack heart valves (inflammation —> commissural fusion)

Question 30

Consequences of aortic valve stenosis

Answer 30

Microangiopathic haemolytic anaemia (shear stress) Left sided heart failure - angina/syncope (fainting) Increased left ventricular pressure - LV hypertrophy

Question 31

Aortic regurgitation causes

Answer 31

``` Aortic root dilation (leaflets pulled apart) Valve damage (endocarditis, rheumatic fever) ```

Question 32

Consequences of aortic valve regurgitation

Answer 32

``` Blood flows back into LV Increased stroke volume Systolic pressure increases Diastolic pressure decreases Bounding pulse LV hypertrophy ```

Question 33

Symptoms/signs of aortic valve regurgitation

Answer 33

``` Head bobbing Quinkes sign (red and pale flushing of nails) ```

Question 34

Mitral valve regurgitation causes

Answer 34

Myxomatous degeneration - weaken chordae tendinae and cause prolapse Damage to papillary muscle after MI Left sided heart failure = LV dilation = valve damage Rheumatic fever

Question 35

Consequences of mitral valve regurgitation

Answer 35

Blood flows back into left atria Increases pre load as more blood enters LV LV hypertrophy

Question 36

Mitral valve stenosis cause

Answer 36

RHEUMATIC FEVER | = commissural fusion of leaflets

Question 37

Consequences of mitral valve stenosis

Answer 37

Increased LA pressure Pulmonary oedema, hypertension, dyspnea (hard to breathe) = RV hypertrophy LA dilation - atrial fibrilation, form thrombus Oesophagus compression, dysphagia (difficult to swallow)