Anatomy and physiology of cardiovascular system

1. Anatomy and Physiology of the
Cardiovascular System

2. • The heart is a hollow, muscular organ situated in
the space between lungs (mediastinum) in the
thoracic cavity.
• It lies obliquely, little more to the left than the right.
• Presents a base above and an apex below. Apex is
about 9 cm to the left of midline at the level of 5th
intercoastal space, ie a little below the nipple and
slightly nearer to midline.
• The base extends to the level of 2 nd rib.
• about 12 cm in length & Approximately 250-300
gm in weight.

3. Position of the heart–Asso. structures
• Inferiorly: The apex rests on the central tendon
of the diaphragm.
• Superiorly: The great blood vessels, i.e. the
aorta, superior vena cava, pulmonary artery
and pulmonary veins.
• Posteriorly: The oesophagus, trachea, lt. and rt.
Bronchus, descending aorta, inferior vena cava
and thoracic vertebrae.

4. • Laterally : The lungs, the left lung overlaps the
left side of the heart.
• Anteriorly : Sternum and anterior portion of
2nd to 5th Thoracic ribs.

5. • The heart is about the size of a clenched fist.
• The heart is composed of three layers:
• Endocardium
• Myocardium
• Pericardium

7. • Endocardium is the inner layer and it consists of
endothelial tissue that lines the inner surface of the heart
and the cardiac valves.
• The myocardium is the middle layer and is composed of
muscle fibers that enable the heart to pump.
• Epicardium is the outer layer, is tightly adherent to the
heart and the base of the great vessels.
• A thin, fibrous, double-layered sac known as the
pericardium surrounds the heart.

9. • The outer layer is known as the Fibrous
pericardium and the inner layer is called the
serous pericardium
• The serous pericardium is further divided as
inner visceral and outer parietal.
• Between visceral and parietal layers is a small
amount of pericardial fluid (15 – 20 ml) that serves as
a lubricant between the two layers.

11. Chambers of the heart
• The heart consists of four chambers:
• right atrium
• left atrium
• right ventricle
• left ventricle

12. Right atrium
• Roughly quadrilateral in shape.
• Receives deoxygenated blood from the
superior and inferior vena cava and the
coronary sinus.
• Interiorly, the atrium is divided into anterior
rough part called atrium proper and posterior
smooth part called sinus venosus.
• It is separated from the right ventricle by the
tricuspid valve and from the left atrium by
interatrial septum.

13. Right Ventricle
• It is a triangular chamber situated to left of right
atrium which receives blood from right atrium and
pumps blood into the pulmonary trunk.
• The interior is rough due to muscular ridges known as
trabeculae carnae.
• It contains cords connecting cusps of valves and the
papillary muscles known as cordae tendanae.
• It is separated from the right atrium and left ventricle
by tricuspid valve and interventricular septum
respectively.

14. Left Atrium
• Quadrangular chamber receives oxygenated
blood from the lungs via pulmonary veins and
pumps it to the left ventricle.
• Muscular wall is thicker than that of right
atrium (~ 3mm)
• Posterior wall presents with opening of 4
pulmonary veins.
• It is separated from right atrium by interatrial
septum and from left ventricle by mitral valve.

15. Left Ventricle
• It is situated posterior to the right ventricle and
is conical in shape.
• Musculature is 3 times thicker than right
ventricle (8 – 12 mm)
• Receives blood from the left atrium and pumps
it in the systemic circulation through aorta.
• The aorta at its origin presents with dilatation
above each cusp known as aortic sinuses of
valsalva.

16. Heart valves
• The cardiac valves are composed of fibrous tissue and
allow blood to flow in one direction.
• They prevent regurgitation of the blood.
• The valves open and close as a result of blood flow
and pressure differences.
• There are 2 pairs of valves in the heart.
- A pair of atrioventricular valves
- A pair of semilunar valves.

17. • The tricuspid and mitral valves are known as
the atrioventricular (AV) valves because they
are located between the atria and the
ventricles.
• The pulmonic and aortic valves are known as
the semilunar valves because each has three
leaflets shaped like half-moons.

18. R i g h t a t r i o v e n t r i c u l a r v a l v e
A n t e r i o r c u s p S e p t a l c u s p
P o s t e r i o r
c u s p
C h o r d a e
t e n d i n e a e
P o s t e r i o r
p a p i l l a r y
m u s c l e
1"'i--=-=- r- - - S e p t a l p a p i l l a r y
m u s c l e
·
..-:r-- -
..,...
- In te r v e n tr i c u Ia r
S e p t u m
A n t e r i o r p a p i l l a r y
m u s c l e
----=:=!---- S e p t o m a r g i n a l
t r a b e c u l a
H e .i l th EdLcl a t l u n L l b r ' a r ' y fc,r l,.,!;!o _plE
:
.
>
©2 0 1 3 v
v v
v v
v
.
h e a l th l ib r a r y .c o m

20. Atrioventricular valves
• The right atrioventricular valve is known as
the tricuspid valve because it has 3 cusps.
• The left atrioventricular valve is known as
bicuspid valve or mitral valve because it has 2
cusps and has a resemblance to a Bishop’s
miter.

21. Parts of atrioventricular valves
• A fibrous ring to which the cusps are attached.
• The Cusps:
-Each cusp or leaflet is flat and projects into the
ventricular cavity.
-Each cusp has a free margin and an attached
margin, has an atrial and a ventricular surface.
-The free margins and ventricular surfaces are rough
due to the attachment of chordae tendinae.
-The valves are closed during ventricular systole by
apposition.

23. • The Chordae tendinae:
-Connect the free margins of the cusps to the
apices of papillary muscles.
-They prevent eversion of free margins of the
cusps towards the cavity of the atrium.
• Papillary muscles:
-Keep the atrioventricular valves competent by
pulling the cordae tendinae during ventricular
systole.

25. Semilunar valves
• The aortic and pulmonary valves are called
semilunar valves because their cusps are
semilunar in shape.
• The cusps form small pockets with their mouths
directed away from the ventricular cavity.
• The free margin of each cusps contains a central
fibrous nodule – the nodule of Arantius – from
each side of which a thin smooth margin, the
lunula extends upto the base of the cusp.

26. • The semilunar valves are closed during
ventricular diastole.
• Opposite the cusps, the vessel walls are
slightly dilated to form the aortic and
pulmonary sinuses.
• The coronary arteries arise from two of the
three aortic sinuses.

27. Circulation of the blood
• The blood supply throughout the body including the heart,
lungs and other body organs and tissues is called
circulation of blood. These are of 3 types:
1. Systemic / General
2. Pulmonary
3. Coronary

28. 1. The blood pumped out from the left ventricle
is carried by the branches of the aorta around
the body and is returned to the right atrium of
the heart by the inferior and superior vena
cava. This is known as systemic circulation.
Systemic Circulation

30. • Aorta:
- It begins at the superior part of left ventricle,
passes up for a short way backwards and
towards the left.
- It is the largest artery in the body, which
carries oxygenated blood from the left
ventricle and distributes it to all parts of the
body.

31. Aortic arch
-----'41,.._..,..-'11-:
Ascending-
thoracic aorta
Aortic root
Descending
thoracic aorta
Abdominal
aorta

32. • Parts of the Aorta:
• The ascending aorta
• The arch of aorta
• The descending aorta – Divided as
- Thoracic aorta
- Abdominal aorta

33. • Ascending Aorta
- The ascending aorta arises from the left ventricle.
- At the root of the aorta, there are 3 dilatations of
the vessel wall called the aortic sinuses.
- The ascending aorta is about 5 cm long.
- It is enclosed in the pericardium.
- After arising from the heart, it runs upward,
forward and to the right.
- It becomes continuous with the arch of aorta at
the level of the sternal angle.

36. • Branches :
- The coronary arteries – right and left, arise
from the right and left coronary sinuses
respectively.

37. The Arch of aorta
• It is the continuation of the ascending aorta.
• It is situated behind the lower half of the
manubrium.
• Branches of the arch of aorta:
-The brachiocephalic trunk: It divides into right
common carotid and right subclavian arteries.
- The left common carotid artery.
- The left subclavian artery.

39. The Descending Aorta
• The descending aorta, which is the
continuation of the arch of aorta, is divisible
into 2 parts:
1. The thoracic part
2. The abdominal part (abdominal aorta).

40. • The thoracic part:
- It is the continuation of the arch of the aorta.
- It lies in the posterior mediastinum.
-The ascending thoracic aorta begins on the left
side of the lower border of T4 vertebra.
-It descends with a slight inclination to the right
and terminates at the lower border of the 12th
thoracic vertebrae.

41. • The Abdominal Aorta
-The abdominal aorta begins in the midline at
the aorta opening of the diaphragm, opposite the
T12 vertebra.
-It ends at the front of the lower part of the
body of L4. It divides itself as 2 terminal
branches, right and left common iliac arteries.

42. Pulmonary Circulation
• The venous blood from the body enters the Rt.
Atrium through superior and inferior vena
cava, passes through the tricuspid valve into
the right ventricle, which then pumps the blood
through the pulmonic valve into the pulmonary
circulation.

44. • This consists of circulation of blood from the right
ventricle of the heart to the lungs and back to the left
atrium.
• The pulmonary artery or trunk carrying deoxygenated
blood, leaves the upper part of the right ventricle of
the heart.
• It passes upwards and divides into left and right
pulmonary arteries at the level of 5th thoracic
vertebra.

45. • The left pulmonary artery runs to the root of
left lung where it divides into 2 branches, one
passing into each lobe.
• The right pulmonary artery passes to the root
of the right lung and divides into 2 branches.
• The larger branch carries the blood to the
middle and lower lobes, and the smaller branch
to the upper lobe.

46. • Within the lungs, these arteries divide and
subdivide into smaller arteries, arterioles and
capillaries.
• The interchange of gases takes place between
capillary blood and air in alveoli of lungs.
• In each lung, the capillaries containing
oxygenated blood join up and eventually form
2 veins.

47. • Two pulmonary veins leave each lung,
returning oxygenated blood to the left atrium
of the heart.
• During atrial systole, this blood passes into the
left ventricle and during ventricular systole, it
is forced into the aorta (1st artery of general
circulation).

48. Coronary Circulation
• The blood supply of the heart is done by coronary
circulation.
• Coronary arteries branch from the aorta just
above the aortic valve.
• These arteries receive about 5% of the blood
pumped from the heart.
• Coronary arteries transverse the heart, eventually
forming a vast network of capillaries.

49. Coronary Arteries
• The left and right coronary arteries and their branches
supply arterial blood to the heart. These arteries
originate from the aorta just above the aortic valve
leaflets.
• The heart has large metabolic requirements,
extracting approximately 70% to 80% of the oxygen
delivered. (other organs consume, on average, 25%).

50. The left coronary artery has three branches.
1-The artery from the point of origin to the first major
branch is called the left main coronary artery.
two bifurcations arise off the left main coronary artery
2- left anterior descending artery (LAD), which
courses down the anterior wall of the heart
3- circumflex artery, which circles around to the lateral
left wall of the heart.

51. • The right side of the heart is supplied by the right
coronary artery, which progresses around to the
bottom or inferior wall of the heart.
• The posterior wall of the heart receives its blood
supply by an additional branch from the right
coronary artery called the posterior descending
artery.

55. • Branches of right coronary artery:
1. Right conus artery (RCA)
2. Right atrioventricular Rami (ramus)
3. Right marginal artery (largest ramus) – part of
rt. atrioventricular rami.
4. Sino atrial nodal artery (SA)
5. Posterior descending artery

56. • Branches of left coronary artery:
1. Left anterior descending (LAD)
2. Left circumflex (LCx)
3. Diagonal arteries

57. • The coronary arteries are perfused during diastole. An
increase in heart rate shortens diastole and can
decrease myocardial perfusion.
• Patients, particularly those with coronary artery
disease (CAD), can develop myocardial ischemia
(inadequate oxygen supply) when the heart rate
accelerates.

58. • Venous drainage of heart:
• The deoxygenated blood from the cardiac
tissues is collected by the veins (oblique vein,
posterior vein of left ventricle, small cardiac
vein, middle cardiac vein and great cardiac
vein) and is collected in the coronary sinus.
• Coronary sinus is the largest venous channel of
the heart and is 2 – 3 cm in length.

59. Cardiac Output
• Cardiac output is the amount of blood pumped out
of the left ventricle in one minute.
• The cardiac output in a resting adult is about 5 L per
minute but varies greatly depending on the metabolic
needs of the body. Cardiac output is computed by
multiplying the stroke volume by the heart rate.

60. • Nerve supply of the heart:
• The heart is innervated by sympathetic
and parasympathetic fibres from the autonomic branch of
the peripheral nervous system.
• The network of nerves supplying the heart is called
the cardiac plexus. It receives contributions from the right
and left vagus nerves, as well as contributions from
the sympathetic trunk. These are responsible for
influencing heart rate, cardiac output and contraction
forces of the heart.

61. • Stroke volume (SV) :The amount of blood ejected
by the left ventricle with each heartbeat .
• The heart rate is 60 to 80 beats per minute (bpm)
• The average resting stroke volume is about 70 mL,
and Cardiac output can be affected by changes in
either stroke volume or heart rate.

62. Cardiac Output/Index
• Cardiac output
– CO = HR (beats/minute) X SV (liters/beat)
– Normal adult: 4 - 8 liters/minute
• Cardiac index
– CI = CO (liter/minute) / Body surface area (m2)
– Normal adult: 2.8 - 4.2 liter/minute/m2
– Normalizes liter flow to body size

63. Stroke Volume
• Preload
• Afterload
• Contractility

64. Stroke Volume
• Preload
– The amount of stretch placed on the cardiac muscle just prior
to systole.
• Afterload
– The force or pressure at which the blood is ejected from the
left ventricle.

65. • Contractility is a term used to denote the force
generated by the contracting myocardium under any
given condition
• The resistance of the systemic BP to left ventricular
ejection is called systemic vascular resistance.
• The resistance of the pulmonary BP to right
ventricular ejection is called pulmonary vascular
resistance
.

66. • The percentage of the end-diastolic volume that is
ejected with each stroke is called the ejection
fraction (EF)
(EF) = 50-70%

67. Conduction System of the Heart
• The heart pumps blood through the body
• This is accomplished by contraction and
relaxation of the cardiac muscle tissue in the
myocardium layer.
• Intercalated discs allow impulses to travel rapidly
between adjacent cells so they function as one
rather than individual cells

68. Intercalated discs

69. • The electrical conduction system controls the
heart rate
• This system creates the electrical impulses and
sends them throughout the heart. These
impulses make the heart contract and pump
blood.
• Consists of modified cardiac cell units that are
as follows

70. • Sinoatrial Node (SA Node)
– Pacemaker of the heart
– Located in back wall of the right atrium near the
entrance of vena cava
– 100s of cells in the Rt. atrium
– Initiates impulses 70 - 80 times per minute without
any nerve stimulation from brain
– Establishes basic rhythm of the heartbeat
– impulses move through atria by the interatrial
pathways causing the two atria to contract.
– At the same time, impulses reach the second part
of the conduction system

71. • Atrioventricular Node (AV Node)
– Small mass of cardiac muscle tissue
– Located in the bottom of the right atrium near the
septum
– Cells in the AV node conduct impulses more
slowly, so there is a delay as impulses travel
through the node
– This allows time for atria to finish contraction
before ventricles begin contracting.
– So that the ventricles are totally filled with blood
before contraction.

73. • Atrioventricular Bundle
– Also called as Bundle of His
– Bundle of specialized cardiac muscle fibers
originating from the AV node
– Divides into Rt. and Lt. branches eventually
becoming Purkinje fibers
– Extend into the septum and walls of the ventricles
and papillary muscles.

74. • As the ventricles contract, blood is forced out
through the semilunar valves into the
pulmonary trunk and the aorta.
• After the ventricles complete their contraction
phase, they relax and the SA node initiates
another impulse to start another cardiac cycle.

75. 1 - Sinoatrial node (SA node)
2 - Atrioventricular node (AV
node)
3 – Bundle of His
4 - Right & Left Bundle Branches
which lead to Purkinje Fibers

76. TYPES OF BLOOD VESSELS
• Artery – carries oxygenated blood away from
the heart
– “distributors”
– Arteriole: small artery
– Pre capillary sphincters: regulate the blood flow
into capillaries

77. • Vein – carries deoxygenated blood towards the
heart
– Great ability to stretch (capacitance)
– Function as reservoirs: blood pools in the valves,
then is pushed forward from the pumping pressure
– Venules: small vein

79. • Capillaries – arterial system switches to venous
system
– “primary exchange vessels”
– Transport materials to and from the cells
– Speed of blood flow decreases to increase contact
time
– Microcirculation: blood flow between arterioles,
capillaries and venules

81. Structure of Blood Vessels
• Tunica adventitia /externa - outermost layer
– Fibrous connective tissue
– Holds vessels open; prevents tearing of vessel walls
during body movements
– Larger in veins than arteries
• Tunica media – middle layer
– Smooth muscle and elastic connective tissue
– Helps vessels constrict and dilate
– Larger in arteries

82. Structure of Blood Vessels
• Tunica intima – innermost layer
– Composed of endothelium
– Semilunar valves present in veins.

83. Circulatory Routes
• Systemic Circulation – blood flow from the Lt.
ventricle to the body & back to the Rt. atrium
• Pulmonary Circulation – blood flow from the
Rt. ventricle to the lungs and back to the Lt.
atrium

84. Circulatory Routes

85. Aorta

86. Systemic Arteries
• Arch of aorta
• Subclavian (Lt. and Rt.)
• Brachiocephalic
• common carotid (Lt.
and Rt.)
• Axillary (Lt. and Rt.)
• Brachial (Lt. and Rt.)
• Radial
• Ulnar
• Abdominal aorta
• Common iliac
• External iliac
• Femoral
• Popliteal
• Posterior tibial
• Anterior tibial
• Dorsal pedis

88. Systemic Veins
• Superior vena cava
• Inferior vena cava
• External jugular
• Internal jugular
• Brachiocephalic (L and
R)
• Subclavian (L and R)
• Cephalic
• axillary
• Basilic
• Median basilic
• Median cubital
• Common iliac
• External iliac
• Femoral
• Popliteal
• Great saphenous
• Small saphenous

90. The cardiac cycle

91. Definition:
The heart acts as a pump and its action
contains a series of events known as the
cardiac cycle.
Taking 74 as an example each cycle lasts about
0.8 seconds and consists of
- Atrial systole
- Ventricular systole
- Complete cardiac diastole

92. ATRIAL SYSTOLE
• Lasts for 0.1 sec
• Atrial depolarization causes atrial systole
• It contributes a final amount of blood to each
ventricle
• End of atrial systole is also end of ventricular
diastole
• End - diastolic volume is 130 ml

93. CARDIAC CYCLE

94. VENTRICULAR SYSTOLE
• Lasts for 0.3 sec
• It is caused by ventricular depolarization
• Isovolumetric contraction lasts for 0.05
seconds when both the semilunar and
atrioventricular valves are closed.

95. Complete cardiac diastole
• Lasts for 0.4 sec
• Both atria and ventricles are relaxed
• The myocardium recovers until it is able to
contract again.
• Atria refill in preparation for next cycle.

96. Heart Sounds
• Heart beat can be heard if the ear or diaphragm
of a stethoscope is placed on chest wall
slightly below the nipple and towards the
midline of the heart.
• 2 sounds are heard - lub-dub.
• The first sound lub is louder and is due to
closure of atrioventricular valves.
• Second sound dub is softer and is due to
closure of aortic and pulmonary valves.

97. THANKS