The cardiac cycle

Question 1

Describe the cardiac cycle

Answer 1

1. Late diastole - all the chambers are relaxed and the ventricles fill passively
2. Atrial systole - atrial contraction forces small amount of blood into the ventricles
3. Isovolumic ventricular contraction - Ventricular contraction pushes the AV valves closed but does not have enough force to push the semilunar valves
4. Ventricular ejection - as the ventricular pressure increases and exceeds the pressure in the arteries, the semilunar valves open and blood is ejected
5. Isovolumic ventricular relaxation - the ventricles relax and the semilunar valves close

Question 2

What is the pulse pressure

Answer 2

The difference between systolic and diastolic pressure

Question 3

Why is there pressure difference between the left and right side of the heart even though they are pumping the same volume of blood

Answer 3

The left side has to pump to the systemic circulation which requires more force and pressure

Question 4

What causes heart sounds

Answer 4

Turbulence in blood flow such as closure of valves

Question 5

What causes the 1st heart sound

Answer 5

Closure of the AV valves - mitral and tricuspid

Question 6

What causes the 2nd heart sound

Answer 6

Closure of the semilunar valves - aortic and pulmonary valves

Question 7

What causes the 3rd heart sound

Answer 7

Rapid filling phase - tricuspid and mitral valve opens and blood flows into the ventricles

Question 8

What causes the 4th heart sound

Answer 8

Active filling phase - atria contract and squeeze the last bit of blood into the ventricles

Question 9

What are the systolic murmurs

Answer 9

Aortic stenosis or mitral regurgitation

Question 10

What makes the lub - 1st sound

Answer 10

mitral and tricuspid valve closing

Question 11

What makes the dub- 2nd sound

Answer 11

Aortic and pulmonary valves closing

Question 12

What are the causes of diastolic murmurs

Answer 12

Aortic regurgitation and mitral stenosis

Question 13

What causes continous murmur

Answer 13

Patent ductus arteriosus

Question 14

What is a patent ductus arteriosus

Answer 14

Ductus arteriosus was a small vessel which joined the aorta to the pulmonary trunk during development and is meant to close after birth - it is a shunt to avoid the lungs during development - if it doesnt close during birth, it causes a continuous murmur