The document discusses the cardiac cycle, which refers to the electrical and mechanical events that occur from the beginning of one heartbeat to the beginning of the next. It includes changes in pressure, blood flow, and heart chamber volumes. Key phases of the cardiac cycle are systole, when the heart contracts, and diastole, when it relaxes and fills with blood. The total duration of the cardiac cycle depends on heart rate, with a normal rate of 75 beats per minute corresponding to a cycle duration of 0.8 seconds. The document also reviews cardiac anatomy and terminology related to the cycle.

2. CARDIAC CYCLE
KRISHNA V GANDHI

3. OBJECTIVES
AT THE END OF THE TEACHING GROUP WILL
BE ABLE TO LEARN :
• To define the cardiac cycle.
• To describe terminologies related to cardiac
cycle.
• To discuss systole and diastole.
• To describe quiescent period.
• To enlist and explain phases of cardiac cycle.
• To conclude phases diagrammatically.

4. REVIEW OF ANATOMY
OF HEART

5. Introduction
• Heart act as a pump.
• 2 separate pump in series:
 Systole: Period of contraction.
 Diastole: Period of relaxation , during which
heart fills with blood.
Protodiastole: The early part of ventricular
relaxation terminating when semilunar valve
closes.

6. DEFINITION
“The electrical and mechanical cardiac events that
occur from the beginning of one heart beat to
beginning of next are called cardiac cycle”
This also includes changes in pressure, blood
flow and volumes in the heart chamber.

7. TERMINOLOGY:
Isovolumetric contraction:
Early phase of systole during which the ventricular
volume does not change, the pressure in ventricles rises
rapidly, but not enough to over come the aortic and
pulmonary end diastolic pressures and open the aortic and
pulmonary valves.
Isovolumetric relaxations:
The phase of diastole following closure of
semilunar valves during which the ventricular pressures
fall rapidly but ventricular volume does not change.

8. Diastole and Systole
• Total duration: reciprocal of heart rate.
• If normal heart rate is 75beats/min.
one beat = 0.8 sec.
• Heart rate increases ,
Cardiac cycle duration decreases
and vice versa.

9. Phases of Cardiac Cycle

10. Quiescent Period
• All the heart chamber are in diastole (relaxed
state) for a period of 0.4sec of cardiac cycle

13. Write the pressure changes in the heart chamber
during systole and diastole.

15. 1. What is total
duration of
cardiac cycle?

16. 2. Define cardiac
cycle?

17. 3. What do you
understand by
systole?

18. 4. Enlist the
phases of atrial
cycle with
duration?

19. 5. What is
Quiescent period?

20. 6. What happens
to cardiac cycle if
heart rate
increases?

21. REFERENCES
• Ashalatha P R ,Textbook of anatomy and physiology
for nurses, 2nd edition Jaypee publication 2018
pg 411-412
• Geetha N, Textbook of physiology for nursing
students ,1st edition Jaypeebrothers medical
publication , 2014 , Newdelhi pg 124
• Waugh Anne,ross and wilson,anatomy and
physiology in health and illness ,11th edition
Elesiver publication 2011 Pg 84-85
• Yalayyaswamy N N,anatomy and physiology for
nurses ,3rd edition , CBS publication 2013,
pg 193

22. THANK - YOU
Life is like riding a bicycle, to stay
balance you must keep moving.