Week 1: Events in the Cardiac Cycle

Question 1

Describe the changes in left ventricular pressure, left ventricular volume, left atrial pressure, and aortic pressure during the following event with respect to PQRST waves for timing: atrial contraction

Answer 1

• Corresponds to P wave

- during onset of atrial contraction, no real changes in pressures and volumes.

Question 2

Describe the changes in left ventricular pressure, left ventricular volume, left atrial pressure, and aortic pressure during the following event with respect to PQRST waves for timing: isovolumic contraction

Answer 2

• QRS wave

- occurs between closer of AV valves and opening of outflow valves, point in which both valves are closed

Question 3

Describe the changes in left ventricular pressure, left ventricular volume, left atrial pressure, and aortic pressure during the following event with respect to PQRST waves for timing: rapid ejection

Answer 3

• QRS wave
• increase in aortic pressure
• atrial pressure doesn’t change
• large increase in ventricular pressure
• drop in ventricular volume

Question 4

Describe the changes in left ventricular pressure, left ventricular volume, left atrial pressure, and aortic pressure during the following event with respect to PQRST waves for timing:isovolumic ventricular relaxation

Answer 4

• T wave
• occurs between closure of outflow valves and opening of AV valves, both valves are closed
• drop in ventricular pressure

Question 5

Describe the changes in left ventricular pressure, left ventricular volume, left atrial pressure, and aortic pressure during the following event with respect to PQRST waves for timing: rapid ventricular filling

Answer 5

• increase in ventricular volume
• slight drop in atrial pressure
• slight decline in aortic pressure

Question 6

Describe the heart sounds and the components responsible for the heart sounds.

Answer 6

S1: outflow of blood during systoles, closing of AV valves (Dub)
S2: Closing of outflow valves (lub)
S3: rapid movement of blood from atria to ventricle (maybe heard in children?)

Question 7

What are the approximate nominal blood pressures for the chambers of the heart? in mmHg

Answer 7

Right atrium: 2-3
Right ventricle: 25/0 (max/min)
Pulmonary trunk: 25/9
Left atrium: 8
Left ventricle: 120/0
Aorta: 120/80