The cardiovascular system comprises the heart and blood vessels, functioning primarily as a transport system for gases, nutrients, and waste. The heart, a muscular organ, has four chambers (two atria and two ventricles) and is surrounded by three tissue layers, ensuring unidirectional blood flow through valves while facilitating both pulmonary and systemic circulation. Key concepts include the cardiac cycle, heart sounds, ECG recordings, and potential disorders affecting heart rate and blood pressure.

1. CARDIOVASCULAR
SYSTEM
Represented by- Radiate

2. INTRODUCTION
 Cardiovascular system consist of heart and blood
vessels.
 It is mainly a transport system.
 It transport respiratory gases, nutrients and
excretory products to various part of the body.
 Blood is the medium through which these substance are
transported.
 Cardiovascular system divided into two main parts:
1. Circulatory system:
 Circulator system consisting of heart which act as a pump
and the blood vessel through which the blood circulates.
2. Lymphatic system:
 Lymphatic system consisting of lymph nodes and lymph
vessel through which colourless lymph flows.

3. HUMAN HEART IN FRONT VIEW

4. HEART
 The heart is a muscular organ in most animals,
which pumps blood through the blood vessels of
the circulatory system.
 The pumped blood carries oxygen and nutrients to
the body, while carrying metabolic waste such
as carbon dioxide to the lungs.
 Heart is a thick, muscular, reddish brown,
conical, hollow and musculotendinous organ.
 It lies in the thorax between lung and behind the
sternum.
 It is about 10 cm long and weights about 300 gm.
 The heart is approximately the size of a closed fist and
is located between the lungs, in the middle
compartment of the chest.

5. FLOW OF BLOOD THROUGH THE HEART

6. STRUCTURE OF HEART
 The heart s composed of the three layers of
the tissues:-
1. Pericardium
2. Myocardium
3. Endocardium

7. 1. PERICARDIUM
 Heart is surrounded by an outer covering layer
known as pericardium.
 It is a thin, transport, two layered sac.
 The inner layer is called visceral pericardium
and outer layer is called parietal pericardium.
 A narrow cavity between two layers is known
pericardial cavity which is filled with a fluid
called pericardial fluid.
 It performs two function:-
a. It allows frictionless movements of heart.
b. It protects the heart from mechanical shock.

8. PERICARDIUM

9. 2. MYOCARDIUM
 The middle layer is known as myocardium
which made heart fibres.
 These muscle fibre found only in the heart.
 It is the muscular tissue of heart, it is not
under voluntary control.
 The myocardium is thickest at the apex and
thin out towards the base.

10. MYOCARDIUM

11. 3. ENDOCARDIUM
 The inner layer is known as endocardium.
 It is smooth thin membrane that permits
smooth flow of blood inside the heart.
 This lines the chamber and valve of the
heart.

12. ENDOCARDIUM

13. CHAMBERS OF HEART
 Heart is made of four chambers that is, two atria and
two ventricles.
 Atria: The atria are smaller with their walls because
they have to push the blood only upto ventricles.
 Both atria or auricles are separated by a inter-
auricular septum which prevents mixing of
oxygenated and deoxygenated blood in heart.
 Ventricles: The ventricles are larger and thicker.
 Left ventricle is much thicker than right ventricle
(about three times) because ventricle has to push the
blood to a body parts while right ventricle has to
push the blood to closely lying lungs only.
 Both ventricle are separated by a thick inter-ventricular
septum. So there is mixing of deoxygenated and
oxygenated blood in heart.

14. CHAMBERS OF HEART

15. A) RIGHT AURICLE
 It receives deoxygenated blood by three
large veins- superior vena cava, inferior
vena cava and coronary sinus.
 Right auricle opens in the right ventricle
through the right atrioventricular valve or
tricuspid valve.
 It regulates unidirectional flow of blood from
right auricle to right ventricle but prevents
the back flow of blood. (with the number of
whitish elastic threads called chordae tendineae
which extends from tricuspid valve to wall of right
ventricle)

16. B) LEFT AURICLE
 It receives oxygenated blood from lungs by
four pulmonary veins. (two each lungs)
 Left auricle open in left ventricle by the help
of the left atrioventricular valve or bicuspid
valve.
 It regulates the flow of blood from left
auricle to left ventricle but prevents back
flow of blood (with the help of chordae
tendineae similar to those in right ventricles.)

17. A) RIGHT VENTRICLES
 From the right ventricles arise from the
pulmonary artery or arch or aorta which
carries deoxygenated blood to the lungs.

18. B) LEFT VENTRICLES
 Left ventricle originates aorta or arch which
carries oxygenated blood to various parts of
the body.
 At the base of each of pulmonary and aortic
arches, there is a valve called pulmonary valve
and aortic valve.
 These allow blood to enter the great artery
from ventricle, but prevent the back flow of
blood into the ventricle.

19. VALVES OF THE HEART
 The opening between right atrium and right
ventricle is guarded by ‘tricuspid valves’.
 The opening between left atrium and left
ventricle is guarded by ‘bicuspid valve’.
 The two atrioventricular valves are one
way that keeps the flow of blood from the
arteries to the ventricles and not the other
way.

20. VALVES OF THE HEART

21. CIRCULATION OF BLOOD THROUGH HEART
 Heart is four-chambered and has complete
double circulation which means blood
possess twice through the heart to supply
once to the body.
 There are two circulation:-
A. Pulmonary circulation
B. Systemic circulation

22. A. PULMONARY CIRCULATION
 In this blood complete its circulation from right
ventricle to left auricle through the lungs.
 It is the part of circulation involving the purification
(oxygenation) of blood in the lungs.
 Here, the right ventricle pumps deoxygenated
blood into pulmonary artery.
 Then the pulmonary artery carries this blood to the
lungs where it is oxygenated.
 Then the four pulmonary veins carry the purified
blood from lungs to left auricle of the heart.
 Then left auricle pumps the blood to left
ventricle.

23. B. SYSTEMIC CIRCULATION
 In this blood completes its circulation from left
ventricle to right auricle through body
organs.
 Here the left ventricle pumps oxygenated
blood into systemic arch which supplies it to
body organ other than the lungs through a
number of arteries.
 Deoxygenated blood from these organs are
returned to the right auricle through two
large veins, superior and inferior vena cava.
 Right auricle pumps the deoxygenated blood
in the right ventricle.

24. CIRCULATION OF BLOOD THROUGH HEART

25. ARTERIAL AND VENOUS SYSTEM
 The heart pumps blood into arteries. The
arteries divide and subdivide and finally end in
capillaries.
 The capillaries later unite to form veins. The
veins returns blood to the heart.
 So arteries carry pure (oxygenated) blood
from the heart.
 The veins carry impure (deoxygenated)
blood to the heart.
 Capillaries are minute channels.
 They receive blood from smaller arteries
(arterioles) and deliver into smaller veins
(venules).

26. ARTERIAL AND VENOUS SYSTEM

27. ARTERIES & ARTERIOLES
 These are the blood vessel that transport blood
away from the heart.
 They vary considerably in size and their wall
consist of three layer of tissue.
 They are; arteries and veins have the same layer of
structure.
1. Tunica adventitia:
 It is the outer layer of fibrous tissue.
2. Tunica media:
 It is the middle layer of smooth muscles and
elastic.
3. Tunica intima:
 It is the inner layer of squamous epithelium
called endothelium.

28. ARTERIES & ARTERIOLES

29. VEINS AND VENULES
 Veins are blood vessel that return blood at
low pressure to the heart.
 The wall of the veins are thinner than those
of arteries but have the same three layer of
tissues.
 They are thinner because there is less muscle
and elastic tissue in the tunica media.
 The veins carry blood at a lower pressure
than arteries.
 The smallest veins are called venules.

30. VEINS AND VENULES

31. CAPILLARIES
 The smallest arterioles break up into a number of
a minute vessel called capillaries.
 Capillary well consist of a single layer of
endothelial cell.

32. FUNCTION OF HEART
 The heart acts as a pump. It maintain a constant
circulation of blood throughout the body. It is achieved
as follows:-
 The superior vena cava and inferior vena cava bring venous
parts of the body to the heart. The venous blood fills the
right atrium.
 When it is full, the right atrium contracts sending blood
to the right ventricle.
 Now, the right ventricles contracts. This send blood to
the lungs through pulmonary trunk (which divides into
right and left pulmonary arteries).
 The blood gets oxygenated in the lungs. The oxygenated
blood is carried by pulmonary veins to the left atrium.
 Now the left atrium contracts and sends blood to the left
ventricle.
 Now the left ventricle contracts and sends blood into the
aorta. This blood is circulated throughout the body except
lungs.

33. CARDIAC CYCLE
 It involves alternate contraction (called
systole) and relaxation (called diastole) of
heart at the rate of 70-72 times per minute at
rest.
 All the chambers do not beat simultaneously.
 Right and left auricles contract
simultaneously while both ventricle also
work simultaneously.
 The sequence of events that occur during
one heart beat is called cardiac cycle.
 Cardiac cycle occurs in two phase:-
I. Systole: A period of contraction
II. Diastole: A period of relaxation

34. CARDIAC CYCLE

35. HEART SOUNDS
 During a cardiac cycle two heart sound can be
heard.
 Totally, four sounds are produced by the
heart.
 The first sound as LUB and the second sound
as DUB can be heard with a stethoscope.
 The third & fourth sounds cannot be heard.

36. 1. LUB OR SYSTOLIC SOUND
 It is heard during the beginning of ventricular
systole and is produce due to rapid closing of
atrioventricular valves to prevents back flow
of blood from the ventricles of atria.

37. 2. DUB OR DIASTOLIC SOUND
 It is heard during the beginning of ventricular
diastolic and is due to rapid closing of semi-
lunar valves to prevents back flow of blood
from the great arteries to the ventricle.

38. ELECTROCARDIOGRAM (ECG)
 It is the recording of electrical activity of the
heart.
 ECG is the instruments which is used to record the
electrical current generated in the heart.
 The heart current can be recorded by connecting
any two parts of the body with this instruments.
 The connections are called as ‘Leads’.
 There are bipolar and unipolar leads.
A. Bipolar leads: they are three type-
i. Lead 1- Electrodes connecting to the right & left
arm.
ii. Lead 2- Right arm & left leg
iii. Lead 3- Left arm & left leg
B. Unipolar leads: they are two type-
i. Unipolar limbs leads- VR, VL, VF
ii. Unipolar chest leads- V1 , V2 , V3 , V4 , V5 & V6

39. ECG WAVES
 During recording electrical activity of the heart
some waves are produced;
 These waves are known as P, Q, R, S and T waves.
 P-wave: is formed due to the stimulation and
contraction of the atria.
 Q,R,S-wave: are formed by the contraction of the
ventricles.
 T-wave: are formed by the relaxation of the ventricles.
 U-wave: are formed due to the continue electrical
activity after the relaxation of the ventricles. It is
very small.
 PR-interval: it represents the time taken by the
impulses to travel from the SA node to AV node. It is
measured from the P-wave.
 Note:- Normal time of PR-interval is 0.12 to 0.16 sec.
 If PR-interval is move than 0.20 seconds it means that
there may be some heart disease.

40. NORMAL ECG GRAPH

42. HEART RATE
 Number of heart beats per minute is known as
the heart rate.
 The normal heart rate is as follows;
 In an adult: 72/minute
 In old age: 75-80/minute
 In newborn child: 130-140/minute
 In children upto 5 years: 90-140/minute
 Generally the heart rate is increased during
exercise, emotion & in some diseased
conditions.
 Heart rate is decreased during sleep, shock
and in some disease.

43. BLOOD PRESSURE
 It is the pressure exerted by the blood vessels
known as B.P.
 The blood pressure which is normally expressed
by arterial blood pressure.
 It has two phase:-
A. Systolic blood pressure: It is the maximum
blood pressure. This occurs during the
systole of heart. (Range 100-120 mmHg)
B. Diastolic blood pressure: It is the minimum
blood pressure. It occurs during the diastole
of heart. (Range 60-80 mmHg)

44.  Cardiac output:
 It is defined as the quantity of blood pumped
by the heart in one minute.
 Pulse pressure:
 It is the difference between systolic and
diastolic blood pressure. It is nearly 40 mmHg.

45. DISORDERS
 Tachycardia: Increase in the heart rate.
 Bradycardia: Decrease in the heart rate.
 Cardiac arrhythmia: It is the disorder in cardiac
rate and rhythm.
 It occurs due to defective impulse formation and
conduction in the heart.
 Angina pectoris: It occurs due to narrowing of
coronary arteries.
 Hypertension: It is a rise in BP above normal.
 Hypotension: It is occur due to low blood
pressure.
 Atherosclerosis: It is the thickening of arterial
walls due to the deposition of fat.
 Phlebitis: It is the infection of the vein wall due
to inflammation or injury.