In this ppt, Cardiac cycle and it's working principle is explained. This will be useful for 8th to 10th grade students.

1. WORKING OF HEART
JEGATHEESWARI KARTHIK

2. VALVES THAT REGULATE THE FLOW OF
BLOOD
1. Right atrio-ventricular valve
2. Left atrio-ventricular valve
3. Pulmonary semilunar valve
4. Aortic semilunar valves

5. RIGHT ATRIO-VENTRICULAR VALVE
•located at the aperture between the right
auricle and the right ventricle.
•Has three thin triangular leaf like flaps or
cusps. That’s why it is called as tricuspid valve

7. RIGHT ATRIO-VENTRICULAR VALVE
• The chordae tendineae are a group of tough, tendinous
strands in the heart.
• They are commonly referred to as the “heart strings” since
they resemble small pieces of string.
• Functionally, the chordae tendineae play a vital role in
holding the atrioventricular valves in place while the heart is
pumping blood.
• They work like a parachute.

8. RIGHT ATRIO-VENTRICULAR VALVE
• The papillary muscles are muscles located in the ventricles of
the heart.
• They attach to the cusps of the atrioventricular valves (also
known as the mitral and tricuspid valves) via the chordae
tendineae.
• Prevent backward flow of blood.

9. LEFT ATRIO-VENTRICULAR VALVE
•It has two cusps.
•That’s why called as bicuspid valve
•Also called as mitral valve

10. PULMONARY SEMILUNAR VALVE
•Located at the opening of right ventricle in to
the pulmonary artery.
•Pocket shaped
•Three in number

11. AORTIC SEMILUNAR VALVES
•Located at the opening of left ventricle in to the
aorta.
•Pocket shaped
•Three in number

13. CIRCULATION OF BLOOD IN HEART
•Both the Auricles contracts first.
•At the same time, ventricles relax or dilate.
•Ventricles are empty at that time.
•The blood from the auricles passes to the
ventricles easily.

14. CIRCULATION OF BLOOD IN HEART
•Next the ventricles contract
•Auricles relax
•The blood from the ventricles tends to return to
atria under pressure.
•Both the tricuspid and bicuspid valves prevent
this.
•The valves get tightened and puffed up and
close the passage.

15. CIRCULATION OF BLOOD IN HEART
•The chordae tendinae hold the flaps of the valves
in position.
•The ventricular blood from the left ventricle enters
aorta and the ventricular blood from the right
ventricle enters pulmonary artery.
•The mouths of the pocket- like valves at the bases
of these two blood vessels face away from the
ventricles.
•Therefore the blood leaving the ventricles passes

16. CIRCULATION OF BLOOD IN HEART
•When the ventricles relax, the blood from the
pulmonary artery and the aorta tends to return.
•The blood fills the pockets of the valves and closes
the passage.

17. HEART BEAT
• Each heart beat or cardiac cycle consists of two steps.
1. The contraction phase ( Systole ) Auricular systole
and Ventricular systole
2. The expansion phase ( Diastole ) Auricular diastole
and ventricular diastole
Each heart beat lasts for about 0.85 seconds.
Systole of atria - 0.15 sec
Systole of ventricles – 0.30 sec
All chambers in relaxed state – 0.40 sec

18. HEART BEAT
•Atrial systole and ventricular diastole
Atrial systole refers to the phase of the cardiac cycle.
During atrial systole the left and right atria contract at the
same time and push blood into the left and right ventricle,
respectively.
•Openings of vena cava and pulmonary vein close
•Semi lunar valves at the roots of pulmonary artery and
aorta are closed producing the DUB sound to prevent
the backflow of blood.

20. HEART BEAT
•Ventricular systole and articular diastole
Ventricular systole refers to the phase of the cardiac
cycle. During ventricular systole the left and right
ventricle contract at the same time and push blood
into the Aorta and pulmonary artery, respectively.
•Tricuspid and bicuspid valves close with LUB sound.
•Auricles draw in blood from pulmonary vein
and vena cava.

22. RATE OF HEART BEAT
• A normal resting heart rate for adults ranges from 60 to 100 beats per
minute.
• Generally, a lower heart rate at rest implies more efficient heart
function and better cardiovascular fitness.
• For example, a well-trained athlete might have a normal resting heart
rate closer to 40 beats per minute.

24. RATE OF HEART BEAT
•Human baby’s heart beat is more
compared to adults??

25. RATE OF HEART BEAT
•Human baby’s heart beat is more
compared to adults??
•They have higher metabolism for
body growth.

27. RATE OF HEART BEAT
•Smaller the size of an animal
faster is the heart beat?????

28. RATE OF HEART BEAT
•Smaller the size of an animal faster is the heart
beat?????
•Small animals have a larger surface area to volume
ratio than large animals. This is why heart rate in
smaller animals is faster than that of larger animals.
• It takes more force to push a given amount of blood
through tiny blood vessels than through big ones, so
the heart has to pump more to push it through.
•

29. PACE MAKER
•The command or impulse starts from SAN
•SAN refers to Sino Atrial Node
•It is located in the walls of the right auricle and
is present near the opening of the superior
vena cava.
•It is also called as PACEMAKER.
•The impulse is relayed to the ventricle with the
help of special conducting fibres.

31. IMPULSE CREATING SYSTEM IN HEART
•AVN – Atrio Ventricular Node.
•It is found near the interarticular septum near
the tricuspid valve.
•Bundle of muscle fibres called Bundle of HIS
begins from AVN and extends to the
interventricular septum.
•Bundle of HIS consists of branches of consists
of branches of fibres running along the wall of

33. ARTERY
Is a vessel which
carries blood away
from the heart to
various organs

34. ARTERY
STRUCTURE
● Progressively branched, decreasing in
size
● Smallest artery breaks into arterioles.
● Have thick and more muscular walls.
● Walls are elastic.
● Have narrower lumen.
● Have no walls in their inner lining.
● Can constrict or dilate to control blood
flow.
● Usually deeply placed.
● Do not collapse when empty.
● Blood flows with jerks and under great
pressure.
● Carry fully oxygenated blood except

35. ARTERY
Is a vessel which
carries blood away
from the heart to
various organs

36. ARTERY
CHARACTERISTI
CS
● Thick muscular walls.
● A narrow lumen.
● The blood in it flows in spurts
which corresponds to ventricular
contraction.

37. VEINS IS A
VESSEL WHICH
CARRIES THE
BLOOD AWAY
FROM THE
ORGANS
TOWARDS THE
HEART

38. VEIN
STRUCTURE
● Progressively unite increasing in size.
● Smallest vein arises from venules.
● Have thin and less muscular walls.
● Walls are non-elastic.
● Have wider lumen.
● Have valves in their inner lining to
prevent backward flow of blood.
● Cannot constrict.
● Usually more superficial.
● Collapse when empty.
● Blood flows continuously and under
very little pressure.
● Carry partially deoxygenated blood
except pulmonary vein.

39. VEIN
CHARACTERISTI
CS
● Thin muscular walls.
● A wider lumen.
● The blood in it flows in uniformly.
● Has thin pocket-shaped valves and
has openings faced towards heart.

40. I wonder...
Why arteries doesn’t have
valves?veind
Veins have valves
but not the
Arteries?

41. I observe...
● Unlike arteries, veins
contain valves that
ensure blood flows in
only one direction.
● Arteries don't require
valves because pressure
from the heart is so
strong that blood is only
able to flow in one
direction.
● Valves also help blood
travel back to the heart
against the force of

42. CAPILLARY IS A
NARROW TUBE
ABOUT ONLY 8
MICROMETER
IN DIAMETER.

43. CAPILLARY
CHARACTERISTI
CS
● They are the smallest blood vessels
in the body:
● They convey blood between the
arterioles and venules.
● Its wall consists of a single layer of
squamous epithelial
cells.Endothelial cells.
● Has no muscles.
● All capillaries in our body extends
upto 1,00,000 Km

44. CAPILLARY
FUNCTIONS
● Outward diffusion of oxygen
● Inward diffusion of carbon dioxide.
● Inward and outward diffusion of
substances like glucose, amino
acids,urea, hormones etc.
● Allow WBC to squeeze out through
capillary walls.

45. Draw conclusions
When we walk in the hot sun
our face turns pink?
When we are in very cool place
our face turns blue?

46. CAPILLARIES ● It has the power of vasodilation
and vasoconstriction which
increases and decreases the blood
supply to the body parts.
● Increased blood supply - pink
● Decreased blood supply- Blue

47. TWO BLOOD
CIRCULATIONS
1. PULMONARY
2. SYSTEMIC

48. PULMONARY
CIRCULATION
● Pulmonary means lungs.
● It is short
● It includes the blood flow by
1. Pulmonary vein
2. Pulmonary artery

49. SYSTEMIC
CIRCULATION
● Major circulation
● Long pathway
● It starts with aorta.
● It includes
1. Aorta
2. Vena cava