The heart as a pump

Question 1

Name the major blood vessels of the heart and describe what it carries.

Answer 1

• pulmonary artery : deoxygenated blood to lungs.
• pulmonary vein : oxygenated blood back to heart.
• superior vena cava : deox. blood from upper body.
• inferior vena cava : deox. blood from lower body.
• aorta : systemic circulation of oxygenated blood.

Question 2

Differentiate between systole and distole.

Answer 2

systole is the contraction and ejection of blood from ventricles whereas diastole is relaxation of filling ventricles. (120/80)

Question 3

Name the valves present in the heart.

*opens and closes depending on differential pressure on each side.

Answer 3

• mitral (bicuspid)
• Tricuspid
  (attach to papillary muscles via chordae tendineae)
• pulmonary valve
• aortic valve

Question 4

Define stroke volume.

Answer 4

The amount of blood pumped out by the left ventricle of the heart in one contraction.
SV = end diastolic vol - end systolic volume

Question 5

explain the structure of cardiac muscle.

Answer 5

• cells interconnected electrically and contract in response to action potentials.
• cardiac action potentials last relatively longer at 280ms.

Question 6

what specialised cardiomyocytes aid the conduction system of the heart?

Answer 6

• SAN pacemaker cells generate AP and activity spreads over atria in atrial systole.
• AVN reached and AP delayed for 120ms till atrial contraction completed.
• ventricular myocardium spread from endocardial to epicardial surface and ventricle contracts from apex up forcing blood out.

Question 7

what changes in terms of timing of systole and diastole in an increased heart beat?

Answer 7

• systole time remains constant and the time of diastole changes and becomes shorter.
• normally 0.35s and 0.55s respectively.

Question 8

what diagram is used to interpret activity of heart and components during heart beat?

Answer 8

• Wiggers diagram.

in notes

Question 9

What is Stenosis?

Answer 9

*valve doesn’t open enough causing obstruction to blood flow.

• increased LV pressure leading to LV hypertrophy.
• left sided heart failure leading to syncope (faint) or angina.
• microangiopathic haemolytic anaemia.

Question 10

what causes aortic stenosis?

Answer 10

• degenerative with senile calcification, fibrosis.
• congenital.
• chronic rheumatic fever causing commissural fusion.

Question 11

what is regurgitation in regards to valves?

Answer 11

• valve doesn’t close all the way causing back leakage when valve should be closed.
• blood back in LV, increasing SV, systolic BP increases and diastolic decreses, bounding pulse (head bobbing, quinke’s sign of red nails with each beat) and LV hypertrophy.

Question 12

what causes aortic valve regurgitation?

Answer 12

• aortic root dilation.

- valvular damage.

Question 13

what causes mitral valve regurgitation?

Answer 13

• weakening of chordae tendineae and papillary muscle prevent prolapse but if degenerates can lead to prolapse.
• papillary damage at heart attack.
• LV dilation stretching valve at L heart failure.
• Rheumatic fever.
• causes LV hypertrophy.

Question 14

what causes mitral valve stenosis?

Answer 14

• main cause rheumatic fever which is an autoimmune inflammation of heart muscle.
• commissural fusion of valve leaflets.

Question 15

what are some mitral valve stenosis effects?

Answer 15

• increased LA pressure so LA dilated leading to atrial fibrillation leading to thrombus forming, oesophagus compression leading to dysphagia.
• pulmonary oedema, dyspnea, pulmonary hypertension all leading to RV hypertrophy.