Human cardiovascular system, organ system that conveys blood through vessels to and from all parts of the body, carrying nutrients and oxygen to tissues and removing carbon dioxide and other wastes. It is a closed tubular system in which the blood is propelled by a muscular heart. Two circuits, the pulmonary and the systemic, consist of arterial, capillary, and venous components. The primary function of the heart is to serve as a muscular pump propelling blood into and through vessels to and from all parts of the body. The arteries, which receive this blood at high pressure and velocity and conduct it throughout the body, have thick walls that are composed of elastic fibrous tissue and muscle cells. The arterial tree—the branching system of arteries—terminates in short, narrow, muscular vessels called arterioles, from which blood enters simple endothelial tubes (i.e., tubes formed of endothelial, or lining, cells) known as capillaries. These thin, microscopic capillaries are permeable to vital cellular nutrients and waste products that they receive and distribute. From the capillaries, the blood, now depleted of oxygen and burdened with waste products, moving more slowly and under low pressure, enters small vessels called venules that converge to form veins, ultimately guiding the blood on its way back to the heart.

1. Prof. Amol B Deore
MVPs Institute of Pharmaceutical
Sciences, Adgaon , Nashik

2.  Cardiovascular system (cardio-heart, vascular-
blood vessels) consists of the heart and
thousands of miles of blood vessels.
 The pumping action of heart ensures constant
circulation of the blood.
 The blood vessels transport the blood, which
carries oxygen, nutrients, hormones, enzymes,
and cellular waste to and from the trillions of
cells of the body.

4.  The human heart is cone shaped around 300
grams in weight, lies in the thoracic cavity in
middle compartment of the mediastinum
cavity of the chest (space in between the
both lung).
 The heart is typically the size of a fist: 12 cm
(5 in) in length, 8 cm (3.5 in) wide, and 6 cm
(2.5 in) in thickness.

6.  The wall of the heart is composed of three
layers: pericardium, myocardium and
endocardium.
 The outermost layer is called the pericardium
which is a triple layered sac that surrounds and
protects the heart.
 The pericardium consists of
1) fibrous pericardium,
2) serous pericardium and
3) visceral layer of serous pericardium.

7.  myocardium
cardiac muscle tissue, makes up about
95% of the heart and is responsible for
its pumping action
 endocardium
It is the endothelial lining of the heart.

10.  The human heart made up of four chambers,
 two upper atria (right and left atrium), and two
lower ventricles (right and left ventricle).
 The interatrial septum separates the atria and
the interventricular septum separates the
ventricles.
 The interventricular septum is much thicker
than the interatrial septum, as the ventricles
need to generate greater pressure when they
contract. The atria are connected to the
ventricles by the atrioventricular valves.
 The thickness of the walls of the four chambers
varies according to their functions.

11.  The right atrium receives deoxygenated blood from
the body and the left atrium receives oxygenated
blood from the lungs.
 The atria are thin walled because they only deliver
blood into the ventricles. When these atria contract
the blood is pushed into the ventricles.
 The left heart pumps oxygenated blood to all the
parts of body (systemic circulation) and the right
heart pumps the deoxygenated blood only to the
lungs (pulmonary circulation) where gas exchange
occurs, i.e. the blood collects oxygen from the
alveolar airsacs and excess carbon dioxide diffuses
into the airsacs for exhalation.
 Thus left ventricle must work harder than the right
ventricle to maintain rate of blood flow.
 The thickness of wall of left ventricle is two to four
times greater than right ventricle.

13.  Valves are made up of dense connective
tissue covered by endocardium.
 Valves open and close according to changes
in pressure in the chambers of heart.
 Valves prevent the back flow of the blood
and permit one directional blood flow.
 The human heart consists of AV valves and
semilunar valves.

14. Atrioventricular Valves (AV Valves)
Atrioventricular
Valve
Location Cusps/ Flaps
Tricuspid valve
In between right atrium and
right ventricle
3 cusps
Bicuspid valve
(mitral valve)
In between left atrium and left
ventricle
2 cusps
 When an AV valves open, the cusps project into the ventricles by the
chordae tendineae.
 Chordae tendineae are tendon like fibrous cords which pull the cusp
in the ventricles due to contraction of papillary muscles (valve
open).
 Blood moves from the atrium into the ventricles through the open
AV valves, thus ensuring a one-way blood flow.

15. Semilunar valve Location Cusps/Flaps
Pulmonary
semilunar valves
At the opening of pulmonary
trunk in right ventricle
3 half-moon
cusps
Aortic semilunar
valves
At the opening of aorta in left
ventricle
3 half-moon
cusps
The semilunar valves are made of three
half-moon cusps that allow blood to flow
only in one direction.

17.  The main types of blood vessels are aorta,
arteries, arterioles, metarterioles,
capillaries, venules, veins and vena cava.
 Arteries carry blood away from the heart to
other organs.
 Medium-sized arteries then divide into small
arteries, which in turn divide into still
smaller arterioles and metarterioles.
 As the arterioles enter a tissue, they branch
into several tiny vessels called capillaries.

19.  The walls of capillaries allow the exchange
of substances between the blood and body
tissues.
 Groups of capillaries within a tissue reunite
to form venules.
 Groups of venules to form larger blood
vessels called veins.
 Veins are the blood vessels that convey
blood back to the heart through vena cava’s.

20. The walls of all blood vessels are composed of
three layers:
 The tunica intima composed of a single layer of
endothelial cells;
 The tunica media made of smooth muscle; and
 The tunica adventitia composed of white fibrous
connective tissue.

21.  The arterial system starts from the aorta of
the heart.
 The arch of aorta is divided into three main
branches:
Brachiocephalic artery,
Right subclavian and
Left common carotid artery.

24.  Veins are made of the same three coats or
tunics as arteries but have less elastic tissues
and smooth muscle.
 They also are capable of distension to adapt
to variations of blood volume and blood
pressure.
 Veins also contain valves that ensure blood
flow in one direction, toward the heart.

26. ARTERY VEIN
Arteries transport the pure
blood from the heart to body
tissue, organs etc.
Veins transport the impure
blood from diff. parts of body
back to the heart
Arteries are thick walled Veins are thin walled
Valves are absent in arteries Valves are present in veins
Lumen is smaller in arteries Lumen is bigger in veins
Arteries are located deeper as
compared to veins
Veins are superficial (easily
identified)
Veins transport pure oxygenated
blood
Veins transport impure
deoxygenated blood
Arteries are red coloured in
appearance
Vein are bluish coloured in
appearance

27. The arteries are the branches of
aorta
The no. of venules unite to form
a vein
Blood flow is rapid & fast in
arteries
Blood flow is slow in veins
Transport blood under high
pressure
Transport blood under low
pressure
Blood moves in pulse No pulse
ARTERY VEIN

30.  Superior vena cava returns the deoxygenated blood
from most of parts of the body superior to the right
atrium of the heart.
 Inferior vena cava returns the deoxygenated blood
from all parts of the body inferior to the heart.
 The blood is transported into the right ventricle
due to opening of the tricuspid valve.
 The right ventricle pumps the blood into the
pulmonary trunk through the pulmonary semilunar
valve. Pulmonary trunk which divides into the right
and left pulmonary arteries.
 Each pulmonary artery carrying blood to the lungs
where it releases carbon dioxide and picks up
oxygen (oxygenated blood).

31.  The oxygenated blood returns to the left
atrium of the heart through four pulmonary
veins.
 The blood is transported into the left
ventricle through the bicuspid (mitral valve).
 The left ventricle pumps the blood into the
ascending aorta through the aortic semilunar
valve, which distributed throughout the
body.

34. Systemic circulation includes the flow of
oxygenated blood from left ventricle through the
aorta to the different body tissues and the
deoxygenated blood returns back to the right
atrium via the superior and inferior vena cava.
Systemic circulation is the circulation of the
blood to all organs of the body except the lungs.
 Blood passes from right atrium in to right
ventricle through the tricuspid valve.
 Right ventricle pumps the blood into
pulmonary trunk. The pulmonary trunk divides
into right and left pulmonary artery, each of
which carries blood to one lung.

35.  As blood flows through the pulmonary capillaries. It
loses CO2 and takes O2. This is called oxygenated
blood.
 The oxygenated blood returns to the left atrium of
heart via pulmonary veins.
 The blood passes into left ventricle though bicuspid
valve.
 Left ventricle pumps the blood into ascending aorta.
Branches of aorta deliver blood to systemic arteries,
arterioles, metarterioles and systemic blood
capillaries.
 In systemic blood capillaries, blood loses O2 and
gains CO2. This blood is called deoxygenated blood.
It returns to the right atrium through superior vena
cava, inferior vena cava and coronary sinus.

37. Pulmonary circulation involves the transport
of deoxygenated blood from the right
ventricle to both lungs through the
pulmonary trunk and returns oxygenated
blood to the left atrium through the
pulmonary veins.

38.  Right ventricle pumps deoxygenated blood in
pulmonary trunk through the pulmonary semilunar
valve. Pulmonary trunk then divides into two
branches: right pulmonary artery which goes into
right lung and left pulmonary artery which goes into
left lung.
 Pulmonary arteries branched into arterioles and
finally into pulmonary capillaries around the alveoli
(air sacs) in the lungs.
 The exchange of O2 and CO2 takes place in between
alveoli and blood. Inhaled O2 passes from the alveoli
into blood. This is oxygenated blood. CO2 passes
from the blood into alveoli and is exhaled.

40.  The pulmonary capillaries unite to form venules
and finally veins. Two pulmonary veins from each
lung transport the oxygenated blood to the left
atrium.
 Contraction of left ventricle pumps the
oxygenated blood into the systemic circulation.

42.  Hepatic portal circulation transports venous
blood (deoxygenated blood) from the stomach,
spleen, small intestine, large intestine,
pancreas and gall bladder back right atrium
through the liver (hepatic-portal vein).

43.  Hepatic-portal vein is formed by union of
gastric vein (stomach), splenic vein (spleen),
mesenteric vein (small intestine), colic vein
(large intestine), pancreatic vein (pancreas) and
cystic vein (gall bladder).
 Hepatic portal vein passes deoxygenated blood
to the liver.
 In the liver small hepatic ducts connected to
hepatic portal vein to form hepatic vein.
 Hepatic vein then transports the blood into
inferior vena cava as shown in Fig

45. Functions
 The nutrients, carbohydrates, fatty acids,
vitamins, proteins obtained from digested food;
are directly entering in to liver for metabolism,
biochemical reactions, storage and energy
production.
 Hepatic Portal Circulation play important role in
drug metabolism.

46.  Coronary circulatory system provides an
oxygenated blood supply to the myocardium
(the heart muscle).
 It arises from the aorta by two coronary
arteries, the left and the right, and after
nourishing the myocardium blood returns
through the coronary veins.

50. The heart possesses the property of
autorhythmicity, which means it generates
its own electrical impulses and beats
The conduction system of the heart
generates and distributes electrical
impulses over the heart, which causes
contraction of the heart.
The sinoatrial node (SA node), also known
as the pacemaker, starts each cardiac
cycle and is found in the superior wall of
the right atrium. It spreads electrical
impulses over both atria causing atrial
contract.

51.  The atrioventricular node (AV node), in the
lower part of the right atrium, sends electrical
impulses to the AV bundle or (bundle of His).
 The bundle of His divides into the right and left
AV bundle branches, distributing the electrical
impulses over the medial surface of the
ventricles.
 Purkinje’s fibers come out from the bundle
branches and distribute the impulses to the cells
of the myocardium of the ventricle causing
ventricular contraction.


53.  The series of events take place during each heart
beat termed as cardiac cycle. In a cardiac cycle
the two atria contract simultaneously while the
two ventricles relax and the two ventricles
contract simultaneously while the two atria relax.
The phase of contraction is called systole and the
phase of relaxation is called diastole.
 The no. of cardiac cycles per minute is about 60-
80.
 An average cardiac cycle takes 0.8 second.

54.  The superior and inferior vena cava supplies the
deoxygenated blood in to right atrium. At the
same time, right & left pulmonary veins
transport the oxygenated blood to left atrium
then AV valves open and blood enters in to the
ventricles.
 The SA node generates a nerve impulse of
contraction which spread over the cardiac
muscles of both atria. It leads to emptying of
atria (atrial systole; 0.1 second) and complete
ventricular filling (ventricular diastole).

56.  The AV node generates its own electrical
impulse, which quickly spreads to the
ventricular muscle via the AV bundle, the left
and right bundle branches and Purkinje
fibres.
 This results in contraction of both ventricles
(ventricular systole; 0.3 second). The right
ventricle pumps blood in to the pulmonary
trunk & artery whereas left ventricle pumps
oxygenated blood in to the aorta.
 This occurs due to opening of both semilunar
valves (pulmonary and aortic valves).

58.  After ventricular contraction, there is
complete cardiac diastole for a period of 0.4
sec. Atria and ventricles are relaxed.
 During this time, cardiac muscles recover
and atria refill for preparation of next
cardiac cycle.

60.  During each cardiac cycle, four heart sounds are
generated. However, only two sounds are loud
enough to be heard by listening through a
stethoscope.
 The sound of the heart beat comes from blood
turbulence caused by closing of heart valves.

61.  Lubb (S1)- sound is generated by turbulence
associated with closing of atrioventricular valves
(tricuspid and bicuspid valve) after ventricular
filling. It is louder and little bit longer than second
sound.
 Dupp (S2)- is second sound generated by
turbulence associated with closing of pulmonary
and aortic semilunar valves after ventricular
contraction. Dupp is shorter and not loud as the
first sound.

62. The number of contractions and relaxations of
myocardium within one minute is known as heart
rate. (no. of beats per min)
1) Normal value: 60-80 beats/ min
2) Average value: 72 beats /min
 Tachycardia
The abnormally increase in heart rate more than
100 beats/minute (>100 beats/min)
 Bradycardia
The abnormally reduction in heart rate less than 50
beats/minute is called as Bradycardia.

63.  Autonomic nervous system (ANS): the heart rate increased in
the exercise, stress, exertion due release of neurotransmitter
like adrenaline in blood and heart.
 Exercise: during the exercise skeleton muscle O2 demand is
increase hence heart rate is also to increase the blood supply of
the muscles.
 Body temperature: Rise in body temperature (fever) increases
heart rate.
 Emotional state: Emotions, thoughts, fear and stress increases
the heart rate.
 Age: Heart rate is very rapid and fast in the infants and
children as compared the adults.
 Chemoreceptors
 Baroreceptors
 Thyroid hormones
 Nicotine and caffeine

64.  Electrocardiography (ECG) is the recording of
the electrical conduction system of the heart.
An EKG translates the heart's electrical activity
into line tracings on paper.
 The spikes and dips in the line tracings are
called waves. Using surface electrodes on the
body, it is possible to record the complex
electrical activity of the heart.

65.  It picks up electrical impulses generated by the
depolarization and repolarization of cardiac
tissue and translates into a waveform.
 The waveform is then used to measure the rate
and regularity of heartbeats, as well as the size
and position of the chambers, the presence of
any damage to the heart, and the effects of
drugs or devices used to regulate the heart,
such as a pacemaker.

67. There are five prominent points on the ECG:
 P wave (atrial depolarisation)
 QRS complex (atrial repolarisation and ventricular
depolarisation)
 T wave (ventricular repolarisation)
 The following table mentions some pathological
patterns that can be seen on electrocardiography,
followed by possible causes.

68. PATTERN POSSIBLE CAUSES
Larger P wave Indicates enlargement of atrium
Enlarged Q wave Indicates myocardial infarction i.e. heart attack
Enlarged R wave Indicates enlargement of ventricles
Flatter T wave Indicates insufficient supply of O2 to myocardium
Larger P-Q interval
Indicates formation of scar tissue in heart due to
coronary artery disease or Rheumatic fever
Larger Q-T interval
Indicates myocardial damage, coronary ischemia or
conduction abnormalities

69.  Blood pressure (BP) is the pressure exerted by
blood upon the walls of blood artery. Blood
pressure is generated by contraction of the
ventricles.
 A person’s blood pressure is usually expressed
in terms of the systolic pressure over diastolic
pressure and is measured in millimetre of
mercury (mmHg).

70.  The systolic blood pressure is the force
exerted by the blood against the arterial wall
during ventricular systole (contraction).
 The diastolic blood pressure is the force
exerted by the blood against the arterial wall
during ventricular diastole (relaxation).
 Normal resting blood pressure for an adult is
approximately 120/80 mm Hg.

71. FACTORS REGULATING BLOOD PRESSURE
1] Short term regulators of blood pressure
A] Mechanical regulators
 Stroke volume
 Cardiac output
 Total volume of blood
 Blood viscosity
 Venous return
 Peripheral vascular resistance
 Total length of blood vessels
 Average blood vessel radius
B] Neural regulators
 Baroreceptors
 Chemoreceptors
 Cardiovascular centre

72. 2] Long term regulators of blood pressure
 Renin angiotensin aldosterone system
 Hormonal regulatory system