1. Heart contracts + relaxes in a rhythmic cycle.
2. Cardiac cycle consists of alternating periods of :
· Systole - contraction phase.
· Diastole - relaxation phase.
3. Cardiac cycle = one complete sequence of systole + diastole
4. Resting adult - cardiac cycle repeated 72 times per minute = resting heart rate.
5. Pulse = causes by elastic recoil of arteries.
6. Ventricular pressure + aortic pressure + ventricular volume:
- changes (in response to the events that occur)
- at different phases of cardiac cycle.
7. During diastole:
- pressure↓of heart chambers decreases
- volume↑ increases (as blood is pumped in).
8. During systole:
- pressure↑of heart chambers increases
- volume↓ decreases (as blood is pumped out).
9. When aortic pressure > ventricular pressure
à semilunar valves shut + vice versa.
10. When ventricular pressure > atrial pressure
à AV valves shut + vice versa.