Heart pumping process , phases ,heart sound and changes in pressure and volumes in heart during pumping process

1. Cardiac Cycle

2. CardiacCycle
Definition:
Theperiod from beginning of one heartbeat
to the beginning of next is called the cardiac
cycle

3. • Thecardiac cycle consists:
– Period of relaxation -diastole,
• during which the heart fills with blood,
– Followed by aperiod of contraction calledsystole.
• duringwhichheart ejects blood

4. CardiacCycle
During systole there is contraction of the cardiac
muscle and pumping of blood from the heart
through arteries.
During diastole, there is relaxation of cardiac muscle
and filling of blood.
Various changes occur in different chambers of heart
during each heartbeat. These changes are repeated
during every heartbeat in acyclicmanner.
•
•
•

5. Divisionsof cardiac cycle
Thecardiac cycle consists of aperiod of relaxation
called diastole, during which the heart fills with blood
this period is followed by aperiod of contraction called
systole.
•
• Thecontraction and relaxation of atria are calledatrial
systole and atrial diastolerespectively.
• Thecontraction and relaxation of ventricles arecalled
ventricular systole and ventricular diastole
respectively.

7. Phases of cardiac
cycle

8. 1. Atrial systole
2. Atrial diastole
3. Isometric contraction
4. Ejection
5. Protodiastole
6. Isometric relaxation
7. Rapid inflow
8. Slow inflow
9. Diastasis

9. TimeIntervals
• Duration of each cardiac cycle: 0.8 sec
• Atrial events
o Atrial systole: 0.11 sec
o Atrial diastole: 0.69 sec
• Ventricular events
o Ventricular systole: 0.27 sec
a. Isometric contraction: 0.05 sec
b. Ejection period: 0.22 sec
o Ventricular diastole: 0.53 sec
a. Protodiastole: 0.04 sec
b. Isometric relaxation: 0.08 sec
c. Rapid filling: 0.11 sec
d. Slow filling: 0.19 sec
e. Last rapid filling: 0.11 sec

11. Atrial systole
Only 10% of blood is forced from atria to ventricles.
It is also known as last rapid filling phase or
presystole.
It is considered as last phase of ventricular diastole.
Contraction of atrial musculature causes the
production of fourth heart sound.

12. Atrial diastole
Occurs after atrial systole.
Simultaneously, ventricular systole also starts.
This is long period because this is the period during
which atrial filling takes place.

13. Isometric contraction period
It is muscular contraction of ventricles in which there is
increase in tension without any change in muscle
fibers.
• Pressure volume changes:
Immediately after atrial systole, the atrioventricular
valves are closed to increase ventricular pressure.
Semilunar valves are already closed.
The pressure is increases sharply under closed
cavity of ventricles.
Closer of atrioventricular valves at the beginning of
this phase produces first heart sound.

14. Significance of isometric
contraction
Pressure rise in ventricles caused by isometric
contraction is responsible for the opening of
semilunar valves, leading to ejection of blood from
ventricles to aorta and pulmonary artery.

15. Ejection period
Due to opening of semilunar valves blood is ejected
out of both the ventricles.
It is of 2 stages:
1. First stage or Rapid ejection period :
It starts immediately after the opening of
semilunar valves.
Large amount of blood is rapidly ejected from
both the ventricles
2. Second stage or slow ejection period
It starts after rapid ejection period
Blood is ejected slowly with much less force.

16. End systolic volume
Ventricles are not emptied at the end of ejection
period and some amount of blood remains in each
ventricles.
Amount of blood remains in ventricles at the end of
ejection period is called as End systolic volumes.
Normal values: 60-80 ml per ventricles

17. Wiggersdiagram

18. Protodiastole
It is the phase of ventricular diastole.
Due to ejection of blood, the pressure in aorta and
pulmonary artery increases and pressure in
ventricles drops.
Because of this semilunar valves closed.
Closure of semilunar valves during this phase
produces second heart sound.

19. Isometric relaxation period
It is the muscular relaxation in the in which tension
decreases without any change in length in muscle
fiber.
All the valves are closed during this phase and both
the ventricles are relaxed as closed cavities.
Only the pressure is decreasing in the ventricles
during this phase.

20. Significance of isometric
relaxation
Due to decrease in intraventricular pressure the
atrioventricular valves are open.
This resulting in opening of atrioventricular valves
and filling of ventricles.

21. Rapid filling phase
Also known as first rapid filling phase.
When atrioventricular valves are open there is
sudden rush of blood from atria to ventricles.
About 70% of blood if filling during this phase.
Rushing of blood into ventricles during this phase
causes production of third heart sound.

22. Slow filling phase
After sudden rush of blood, the ventricles filling
becomes slow.
It is also known as diastasis.
About 20% of filling is occurs in this phase.

23. Last rapid filling phase
It coincides with first phase of atrial systole.
Atria contracts and push a small amount of blood
into ventricles.
It is also known as ‘atrial kick’.
About 10% of filling takes place during this phase.

24. End diastolic volume
It is the amount of blood remaining in each ventricles at
the end of diastole is known as End diastolic volume.
Normal value: 130-150 ml per ventricle

25. Phasesof the Cardiac Cycle
Figure 20.16

26. Intra-atrial pressure changes
during cardiac cycle
Pressure develops inside atria is called intra-atrial
pressure
Significance
It is responsible for:-
• Opening of atrioventricular valves
• Ventricular filling

27. Max. and Min. pressure in atria
Left atrium: Max. pressure – 7-8 mmHg
Min. pressure – 0-2 mmHg
Right atrium: Max. pressure – 5-6 mmHg
Min. pressure – 0-2 mmHg

28. Intra-ventricular pressure
changes during cardiac cycle
Pressure develops inside ventricle is called intra-
ventricular pressure
It is essential for circulation of blood.
It is because blood flow through both circulation is
depend upon the pressure at which blood is pumped
out of ventricles.
The pressure in left ventricle is always more than the
right ventricle.

29. Max. and Min. pressure in ventricles
Left ventricle: Max. pressure – 120 mmHg
Min. pressure – 5 mmHg
Right ventricle: Max. pressure – 25 mmHg
Min. pressure – 2-3 mmHg