the heart as a pump

Question 1

does systemic circulation or pulmonary circulation occur at higher pressure and which side of the heart does each?

Answer 1

systemic occurs at a higher pressure as it is to the rest of the body and is conducted by the left side as a result myocardium is thicker on the left. whereas pulmonary circulation is to the lungs by the right side.

Question 2

what does the pulmonary vein do?

Answer 2

brings oxygenated blood to the heart

Question 3

where does blood that enters the superior vena cava and inferior vena cava come from

Answer 3

deoxygenated blood from the top of the body enters the superior vena cava and deoxygenated blood from the lower part of the body enters via the inferior vena cava

Question 4

how much blood does each ventricle pump any rest

Answer 4

70ml

Question 5

what causes cardiac cells to contract and what does this cause a rise in

Answer 5

cardiac cells contract in response to action potentials.

action potentials cause a rise in intracellular calcium

Question 6

how do c cardiac cells communicate with each other

Answer 6

via gap junctions allowing unimpeded signal ( action potential)

Question 7

what is different about the mitral valve compared to the others

Answer 7

it only has two leaflets whereas the other valves have three leaflets

Question 8

what muscles are the cusps of mitral and tricuspid valves attached to and how are they attached

Answer 8

to papillary muscles via chordae tendineae

Question 9

which cells generate an action potential and where are they found

Answer 9

pacemaker cells in sinoatrial node generate an action potential. This is where the signal originates

Question 10

what happens to signal created in sinoatrial node

Answer 10

it spreads over the atria during atrial systole.
when it reaches the atrioventricular node it is delayed for 120 seconds allowing the atria to finish contracting. the excitation now spreads down the septum between ventricles.
next it spreads through ventricular myocardium from inner (endocardial) to outer (epicardial) surface.
ventricle contracts from the apex up forcing blood through outflow valves

Question 11

what are the 7 phases of the cardiac cycle

Answer 11

1) atrial contraction
2) isovolumetric contraction
3) rapid ejection
4) reduced ejection
5) isovolumetric relaxation
6) rapid filling
7) reduced filling

Question 12

when heart rate increases how does this affect diastole time and systole time?

Answer 12

systole time stays the same and diastole time decreases

Question 13

what does a p wave in an egg represent

Answer 13

depolarisation of atria

Question 14

what does the QRS complex in an ECG represent

Answer 14

depolarisation of ventricles

Question 15

what does the t wave in an ECG represent

Answer 15

ventricular repolarisation

Question 16

what occurs in phase 1 of cardiac cycle

Answer 16

atrial contraction
‘A wave’ on ECG as atrial pressure increases
atrial kick- atria contracting only accounts for final 10% of blood filling ventricles. the rest fills passively as the valves open
mitral/ tricuspid valve open but aortic/pulmonary valve closed

Question 17

what occurs in phase 2 of cardiac cycle

Answer 17

isovolumetric contraction
mitral valve closes as intraventricular pressure exceeds atrial pressure. this causes ‘c wave’ in atrial pressure curve( as the valve closes it bulges back into the atria)
closure of mitral and tricuspid valve causes first heart sound(lub) known as S1.

Question 18

what occurs in phase 3 of cardiac cycle

Answer 18

rapid ejection
begins when intraventriclaur pressure exceeds pressure in aorta causing aortic valve to open.rapid decrease in ventricular volume as blood is ejected into aorta.
‘X descent’ is present in the atrial pressure curve as when the ventricles contract the atrial base is pulled down decreasing the pressure.

Question 19

what occurs in phase 4 of cardiac cycle

Answer 19

reduced ejection
repolarization of ventricle(t wave) leads to a decrease in tension and the rate of ejection begins to fall.
‘v wave’ in atrial pressure curve as atrial pressure increases due to the continued venous return from the lungs.

Question 20

what occurs in phase 5 of cardiac cycle

Answer 20

isovolumetric relaxation
intraventricular pressure falls below aortic pressure so there’s a brief back flow of blood causing the aortic valve to shut (seen as discrotic notch in aortic pressure curve)
closure of aortic and pulmonary valves results in the second heart sound (dub-s2)

Question 21

what occurs in phase 6 of cardiac cycle

Answer 21

rapid filling
intraventricular pressure is lower than atrial pressure causing mitral valve to open. this causes a fall in atrial pressure which is seen as the ‘y-descent’ on atrial pressure curve

Question 22

what is s3

Answer 22

ventricular filling is normally silent but sometimes a third heart sound can be present. this is normal in children but a sign of pathology in adults

Question 23

what occurs in phase 7 of cardiac cycle

Answer 23

reduced filling( diastasis-middle stage of diastole) as ventricles reach its inherent relaxed vol.

Question 24

what is stenosis

Answer 24

valve doesn’t open enough obstructing blood flow.

Question 25

what is regurgitation

Answer 25

valve doesn’t close enough causing back leakage

Question 26

what are the causes of aortic valve stenosis

Answer 26

degenerative- senile calcification/fibrosis
congenital- bicuspid form of valve
autoimmune-chronic rheumatic fever,inflammation

Question 27

what happens in aortic valve stenosis

Answer 27

increased LV pressure causing LV hypertrophy

left sided heart failure causing syncope (fainting) or angina

Question 28

what causes aortic valve regurgitation

Answer 28

aortic root dilation (leaflets pull apart)

valvular damage

Question 29

what happens in aortic valve regurgitation

Answer 29

systolic pressure increases
diastolic pressure decreases
bounding pulse(head bobbing, quinke’s sign which is when the nail bed flushes red and pale for each beat of the heart)
LV hypertrophy

Question 30

what is mitral valve prolapse and how is it prevented

Answer 30

it is the bulging of one or both of the mitral valve flaps (leaflets) into the left atrium.
prevented by papillary muscle and chordae tendineae

Question 31

why can mitral valve regurgitation cause LV hypertrophy

Answer 31

as some blood leaks back into LA increasing preload as more blood enters LV in subsequent cycles.

Question 32

what causes mitral valve stenosis

Answer 32

rheumatic fever

Question 33

what can happen in mitral valve stenosis

Answer 33

increased LA pressure causes the following :
pulmonary oedema
dyspnea- difficulty in breathing
the above 3 cause RV hypertrophy
enlargement of LA causes oesophagus compression and atrial fibrillation(which is irregular heart rhythm, this can eventually lead to clots in heart )