Cardiac Cycle

Question 1

What is meant by the following terms:
- Cardiac output
- Heart rate
- Stroke volume

Answer 1

• CARDIAC OUTPUT - Volume of blood pumped by heart per minute
• HEART RATE - heart beats per minute
• STROKE VOLUME - Amount of blood pumped by heart during each systolic contraction

Question 2

What is the difference between EDV and ESV?

Answer 2

Both refer to amount of blood in RV and/or LV at end of:
- EDV - Diastolic filling
- ESV - Systolic contraction

Question 3

What is ejection fraction?

Answer 3

• Percentage of blood leaving the heart per beat
• (SV/EDV) * 100

Question 4

Define inotropy and chronotropy

Answer 4

• INOTROPY - Cardiac contractility
• CHRONOTROPY - Heart rate

Question 5

What does the cardiac cycle describe and how can its duration be calculated?

Answer 5

• Sequence of electrical and mechanical events leading to blood ejection from heart
• Duration = 60/Heart rate