COLLEGE OF NURSING AND MIDWIFERY, YOLA

DEPARTMENT OF ANATOMY AND PHYSIOLOGY

THE CARDIOVASCULAR SYSTEM

By

Mr Miwa G.L

OUTLINE

✓ Introduction
✓ Development of the heart
✓ Anatomy of the heart
✓ Layers of the heart
✓ Interior of the heart
✓ The Aorta
✓ The circulatory system
✓ Circulation of blood
✓ Congenital heart defects
✓ Cardiac output
✓ Conducting system of the heart
✓ Cardiac cycle
✓ Blood pressure
✓ Pulse
✓ Heart sounds

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 THE CARDIOVASCULAR SYSTEM
The cardiovascular system circulates blood continuously throughout the body to
deliver oxygen and nutrients to the body’s organs and tissues and to dispose of their
excreted wastes.
The cardiovascular system is composed of the heart and the vascular system. The heart
includes the cardiac muscle, atria, ventricle, valve, coronary arteries, cardiac veins,
electrical conducting structures, and cardiac nerves.
The vascular system is composed of the blood vessels of the body: the arteries,
arterioles, veins, venules and capillaries.
The major functions of the cardiovascular system are transporting nutrients and
oxygen to the body, removing wastes and carbon dioxide and maintaining adequate
perfusion of organs and tissues.

THE HUMAN HEART

DEVELOPMENT OF THE HUMAN HEART

The human heart, derived from mesoderm, begins as two simple endothelial tubes
that quickly fuse to form a single chamber or heart tube that is busily pumping blood
by the 23rd day of gestation.

One or two days later, the tube develops four slightly bulged areas that represent the
earliest heart chamber. The four(4) chambers developed by day 25 are the following;
1. Sinus Venosus: this chamber initially receives all the venous blood of the
embryo. It will become the smooth walled part of the right atrium and the
coronary sinus. It also gives rise to the sinoatrial node

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 2. Atrium: this embryonic chamber eventually becomes the pectinate muscle
ridged parts of the atria.
3. Ventricle: the strongest pumping chamber of the early heart, the ventricle gives
rise to the Left ventricle.
4. Bulbus Cordis: this chamber, plus its cranial extension, the truncus arteriosus,
give rise to the pulmonary trunk, the first part of the aorta, and most of the
right ventricle.
During the next three weeks, the heart tube exhibits dramatic contortions as it
undergoes right ward looping and major structural changes that convert it into a four
chambered organ, capable of acting as a double pump all without missing a beat. The
ventricle moves caudally and the atrium cranially, assuming their adult positions. The
heart divides into four definite chambers via a number of stages, then the midline
septum forms and the bulbus cordis split into the pulmonary trunk and ascending
aorta. After the second month, few changes occur until birth. The interatrial septum
in the fetal heart is incomplete. The foramen ovale(i.e “oval door”) connects the two
atria and allows blood entering the right to bypass the pulmonary circuit and the
collapsed, non-functional fetal lungs. Another lung bypass, the ductus arteriosus
exists between the pulmonary trunk and the aorta. At or shortly after birth, those two
shunts described, close, thereby completing the separation between the right and left
sides of the heart. In the adult heart, the position of the foramen ovale is revealed by
the fossa ovalis and the ligamentum arteriosum is the fibrous remnant of the ductus
arteriosus.

ANATOMY OF THE HEART

The heart is a cone shaped hollow muscular organ. It is about the owner’s closed fist.
It has mass of between 250 – 350grams. It is enclosed within the mediastinum, the
medial cavity of the thorax, the heart extends obliquely from 12 to 14cm( about 5
inches) from the second rib to the fifth intercostal space. As it rests on the superior
surface(convexity of the dome) of the diaphragm, the heart lies anterior to the
vertebral column and posterior to the sternum. The lungs flank the heart laterally and
partially obscure it. Approximately 2/3 of the mass lies to the left of the midsternal line,
the balance projects to the right.
Its broad, flat, base or posterior surface, about 9cm(3.5 inches) wide and directly
toward the right shoulder. Its apex points inferiorly toward the left rib. If you press
your fingers between the fifth and sixth ribs just below the left nipple, you can easily
feel your heart beating where the apex contracts the chest wall. Hence, this site is
referred to as the point of maximal intensity(PMI) or point of maximum impulse(PMI).

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Blood Supply
The left and right coronary arteries supply the heart with blood, while the venous
drainage is by the great cardiac veins which empty into the coronary sinus and
subsequently into the right atrium.
Surface Marking
To mark the position of the heart in the chest, a line about 1cm is drawn on the 3rd
right rib from the midline and moving slightly upwards to the left, a line is drawn 2cm
on the second rib, from the midline; by joining the two points, the base of the heart is
obtained.
To get the apex beat, a line is drawn about 9cm from the midline on the 5th intercostal
space which corresponds with the midclavicular line, just beneath the left nipple,
gives the exact apex beat of the individual.

LAYERS OF THE HEART

The heart is composed of three layers of tissue, which are given as follows;
1. Pericardium
2. Myocardium
3. Endocardium
PERICARDIUM
The heart is enclosed in a double walled sac called the pericardium( peri= around;
cardi= heart). The superficial part of this sac is the fibrous pericaridium. This tough,
dense connective tissue layer, protects the heart, anchors it to surrounding structures
and prevents overfilling of the heart with blood. Deep to the fibrous pericardium is
the serous pericardium, a thin, slippery, two-layer serous membrane. Its parietal layer
lines the internal surface of the fibrous pericardium. At the superior margin of the
heart, the parietal layer attaches to the large arteries exiting the heart and then turns
inferiorly and continues over the external heart surface as the visceral layer, also called
the epicardium; (Epi = upon , cardi = heart), which is an integral part of the heart wall.
Between the parietal and visceral layers is the slit like pericardial cavity(potential

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space), which contains a film of serous fluid. The serous membrane, lubricated by the
fluid, glide smoothly past one another during heart activity, allowing the mobile heart
to work in a relatively friction- free environment.
MYOCARDIUM
The myocardium is composed of specialized muscle tissue known as cardiac muscle.
This muscle is found exclusively in the heart. It is not under the control of the will, but
like voluntary muscle, cross stripes can be seen on microscopic examination. Each
fibre has a nucleus and one or more branches. The ends of the cells and their branches
are in very close contact with the end and branches of adjacent cells. This arrangement
gives cardiac muscle the appearance of being a sheet of muscle rather than a very large
number of individual cells. Because of the end to end contiguity of the fibres, each one
does not need to have a separate nerve supply. When an impulse of contraction is
initiated it spreads from cell to cell and thus over the whole “sheet” of muscle. The
myocardium is thickest at the apex and thins out toward the base.
ENDOCARDIUM
This form a lining to the myocardium and is a thin, smooth glistening membrane
consisting of flattened epithelial cells continuous with the lining of the blood vessels.

CHAMBERS OF THE HEART/INTERIOR OF THE HEART

The interior of the heart is divided into four(4) cavities called chambers that receive
the circulating blood. The two(2) superior chambers are called the right and left atria(
atrium court or hall). Each atrium has an appendage called auricle(auris = ear) so
named because its shape resembles a dog’s ear. The lining of the atria is smooth, except
for the anterior walls and the lining of the auricles, which contain projecting muscle
bundles that are parallel to one another and resemble the teeth of a comb. They are
called pectinate muscles. Those bundles give the lining of the auricles a ridged
appearance.
The atria are separated by a partition called interatrial septum. A prominent feature
of this septum is an oval depression, the fossa ovalis, which corresponds to the site of
foramen ovale, an opening in the interatrial septum of the fetal heart.
The two inferior chambers are the left and right ventricles. They are separated from
each other by an interventricular septum. The muscle tissue of the atria and ventricles
is separated by connective tissue that also forms the valves. The valve separating the
right atrium from the right ventricle is called the right atrioventricular valve(tricuspid
valve) having 3 flaps or cusps, while the valve separating the left atrium from the left
ventricle is called left atrioventricular valve(bicuspid/mitral valve) having two flaps
or cusps. The valves are prevented from opening upwards by the chordae tendineae(
tendinous cords), which extend from the inferior surface of the valve cusps to the
walls to the walls of the ventricles which have little muscle projections, called
papillary muscles to which the chordae tendineae are attached.

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This ‘cardiac skeleton’ effectively divides the myocardium into two separate muscle
masses. Externally, a groove known as coronary sulcus separates the atria from the
ventricle. It encircles the heart and houses the coronary sinus and circumflex branch
of the coronary artery. The anterior interventricular sulcus and posterior
interventricular sulcus separate the left and right ventricle. The sulci contain coronary
blood vessels and a variable amount of fat.

BLOOD FLOW THROUGH THE HEART

The two largest veins of the body, superior and inferior venae cavae, empty their
contents into the right atrium. This blood passes via the right atrioventricular valve
into the right ventricle and from the right ventricle, it is pumped into the pulmonary
trunk which divides into the right and left pulmonary arteries. These arteries carry the
venous blood to the lungs where interchange of gases occur. The arterial blood is
carried from each lung by two pulmonary veins and the four(4) pulmonary veins
empty their contents into left atrium of the heart. This blood passes through the left
atrioventricular valve into the left ventricle and from here, the aortic valve opens
allowing the blood to flow from the left ventricle into the aorta, the first artery of the
general circulation.

AORTA
The aorta is the main artery in the body. For descriptive purposes, the aorta is divided
into two parts. The aorta commences at the 3rd left intercostal space from the aortic
orifice.
(a) Thoracic aorta.
(b) Abdominal aorta
The thoracic aorta is the part of the aorta situated in the thorax and it is described in 3
portions;
1. The ascending aorta
2. The arch of the aorta
3. The descending aorta
The Ascending Aorta: is about 5cm in length and lies behind the sternum. The right
and left coronary arteries arise from the aorta just above the level of the aortic valve,
these arteries supply the tissues of the heart with oxygenated blood. The venous blood
is drain into the right atrium via the coronary sinus.
The Arch of Aorta: is a continuation of the ascending aorta. It begins behind the
manubrium sterni and runs upwards, backwards and to the left of the trachea passing
down to the left of the trachea to continue with the descending aorta. Three branches
are given off from the superior convexity of the arch of the aorta;
• The innominate or branchiocephalic artery or trunk
• Left common carotid artery

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 • Left subclavian artery
The branchiocephalic artery divides into the right common carotid artery and right
subclavian artery at the level of the sternoclavicular joint.
The Descending Aorta: is continuous with the arch of the aorta and begins at the level
of the 4th thoracic vertebra. It extends downwards on the anterior surface of the bodies
of the thoracic vertebrae to the level of the 12th thoracic vertebra, where it transverse
the diaphragm posteriorly emerging in the abdominal cavity as the abdominal aorta.
The descending aorta in the thoracic cavity gives off branches to supply the organs in
the cavity and the wall of cavity; the bronchial arteries supplying the bronchi, lungs,
and lymph nodes at the root of the lungs; the esophageal arteries supplying the
esophagus.
The Abdominal Aorta: This is the continuation of the thoracic aorta. The name
changes as the thoracic aorta enters the abdominal cavity by passing behind the
diaphragm at the level of T12( 12th thoracic vertebra). It descends in front of the bodies
of the vertebrae to the level of the 4th lumbar vertebra, where it divides into the left
and right common iliac arteries.
Many branches arise from the abdominal aorta, some of which are paired and some
unpaired. The paired branches are;
• The inferior phrenic arteries supplying the diaphragm
• The renal arteries: supplying the kidneys and adrenal glands.
• The testicular arteries: supplying the testis in male and the ovarian arteries
supplying the ovaries in female
The unpaired branches of the abdominal aorta are as follows;
• The coeliac trunk(axis): about 1.25 cm in length arises immediately below the
diaphragm divides into 3 branches;
➢ The common hepatic artery - supplying the liver, gall bladder, part of
the stomach, duodenum and pancreas.
➢ The left gastric artery – supplies the stomach
➢ The splenic artery artery – supplies the pancreas and the spleen
• The superior mesenteric artery branches between the coeliac axis and the renal
arteries. It supplies the whole of the small intestine and proximal half of the
large intestine.
• The inferior mesenteric artery arising from above the point of the 4th lumbar
vertebra, 4cm away, supplies the distal half of the large intestine and part of
the rectum.

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 THE CIRCULATORY SYSTEM
The circulatory system or vascular system is divided into two parts;
1. The blood circulating system, consisting of the heart and the blood vessels
through which blood circulates.
2. The lymphatic system, which consists of lymph nodes and lymph vessels
through which lymph flows.
The two systems communicate with one another and are intimately associated.

Diagram showing lymphatic and blood circulatory system

The Blood Vessels

These are the many types;
a. Arteries
b. Arterioles
c. Veins
d. Venules
e. Capillaries

Diagram showing connections of blood vessels

The Arteries
These vessels which transport oxygenated blood away from the heart, with the
exception of the pulmonary arteries, which transports deoxygenated blood. They are
usually deeply situated and have smaller lumen than their corresponding veins and
they do not have many valves along their course.

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Structurally, consists of three layers of tissue;
i. The tunica adventitia( externa) or outer layer of fibrous tissue
ii. The tunica media or middle layer of smooth muscle and elastic tissue
iii. The tunica intima(interna) or inner layer of squamous epithelium called
endothelium.

Arteries usually divide and subdivide into tiny branches called arterioles(smallest
arteries) whose tunica media consist almost entirely of smooth muscle.
Veins
These are the blood vessel which transport deoxygenated blood to the heart with the
exception of the pulmonary vein which transport oxygenated or arterial blood. They
are usually superficially situated and are bluish in appearance. They have numerous
valves because they are meant to drain blood from tissue all back to the heart and they
are said to unite. Structurally they have the same kind of walls as the arteries, there
walls consist of three tissue coats or tunics surrounding their lumen. The smallest of
veins are called venules.
The Capillaries
The small arteries known as the arterioles break up into a number of minute vessels
called capillaries. The wall of a capillary is composed of a single layer of endothelial
cells which is very thin and permits the passage of water and other small molecules
substances. Their diameter is approximately by 7 µm. their walls are characterized by
a single wall of endothelial cells and have pores, making it semi permeable.

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 Difference between Arteries and veins
Features Arteries Veins
Blood They carry blood away from the They carry blood from
Circulation heart to the tissues. tissues to the heart
Blood Type They carry oxygenated blood They carry deoxygenated
except pulmonary artery blood except pulmonary
vein
Thickness Arteries have thick elastic They have thin non elastic
muscular walls. less muscular wall.
Position They are usually positioned They are positioned
deeper within the body closer beneath the surface
of the skin
Valves Valves are absent Valves are present
Lumen Narrow lumen Wide lumen
Pressure Blood flow under high pressure Blood flow under low
pressure
Color Reddish in color Bluish in color
Walls More rigid Collapsible walls
Pulse Detectable in arteries Not detectable in veins

THE CIRCULATION OF BLOOD

Four systems are discussed when considering the circulation of blood throughout the
body;
a. The pulmonary circulation
b. The systemic or general circulation
c. The portal circulation
d. Coronary circulation

THE PULMONARY CIRCULATION

The pulmonary circulation consists of the circulation of blood from the right ventricle
of the heart to the lungs and back to the left atrium.
The pulmonary artery carrying deoxygenated blood, leaves the upper part of the right
ventricle of the heart. At the level of the 5th thoracic vertebra, it divides into a left and
right pulmonary artery. The left pulmonary artery, runs to the root of the left lung
where it divides into two branches, one passing into each lobe. The right pulmonary
artery passes to the root of the right lung and divides into 2 branches. The long branch
carries blood to the middle and lower lobes and the smaller branch to the upper lobe.

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Within the lung these arteries divide and subdivide into smaller arteries, subsequently
becoming arterioles and capillaries. It is between the capillaries and the alveoli that
exchange of gases occurs in each lung, the capillaries containing oxygenated blood,
join up and eventually form venules and then veins. Two pulmonary veins leave each
lung, therefore four pulmonary veins return oxygenated blood to the left atrium of the
heart. During atrial systole this blood passes into the left ventricles and during
ventricular systole, it is force into the aorta and then into the general or systemic
circulation.
SYSTEMIC CIRCULATION
The blood leaves the left ventricle by the aorta. This breaks up into smaller arteries,
which carry the blood to the different parts of the body. They divide and subdivide
until the arterioles are reached and then the capillaries. These capillaries which are
form become veins and carry the blood to the heart. The veins unite and unite again
until finally two large venous trunks are formed referred to as the inferior vena cava,
which collects the blood from the trunk and lower extremities and the superior vena
cava, which collects blood from the head and upper extremities. Both of these vessels
empty into the right atrium of the heart.
PORTAL CIRCULATION
Portal circulation which is a venous return to the heart. It is not by the most direct
route. Venous blood passes from the abdominal part of the GIT and the spleen via the
liver and the IVC to the heart. In this way blood with a high concentration of nutrient
materials goes to the liver first where certain modifications take place including the
regulation of their supply to other parts of the body.
Veins of the hepatic portal system are as follows;
• The hepatic portal vein receives blood from the stomach via the left and right
gastroepiploic veins, the right and left gastric veins.
• The splenic vein drains blood from the spleen, pancreas, and parts of the
stomach joins the hepatic portal vein.
• The cystic vein drains blood from the gallbladder and joins the portal vein.
• The inferior mesenteric vein return venous blood from the rectum, sigmoid
colon and descending colon and joins the splenic which in turn joins the hepatic
portal veins.
• The superior mesenteric vein drains blood from the small intestine, caecum, the
ascending and transverse colon and then unite with splenic vein to form the
portal vein.
• Pancreaticoduodenal vein drains blood from the pancreas and duodenum and
joins up with the portal vein.

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In the liver, following the traversi ng of the portal vein and the common hepatic artery,
the vein breaks down into a capillary system and unity with capillaries of the common
hepatic artery which bring blood from the aorta. This dual blood supply is collected
by a system of veins which unite to form the hepatic vein conveying blood to the
inferior vena cava and subsequently to the right atrium of the heart.

CORONARY CIRCULATION
Although the heart is more or less continuously filled with blood, this blood provides
little nourishment to heart tissue(the myocardium is too thick to make diffusion a
practical means of nutrients delivery).
The coronary circulation, which is the functional blood supply of the heart, is the
shortest circulation in the human body. The arterial supply of the coronary circulation
is provided by the right and left coronary arteries, both arising from the base of the
aorta, at its commencement from the left ventricle, and encircling the heart in the
coronary sulcus. The left coronary artery runs toward the left side of the heart and
then divides into its major branches: anterior interventricular artery (clinically called
left anterior descending artery)which follows anterior interventricular sulcus and
supplies blood to the interventricular septum and anterior walls of both ventricles;
and the circumflex artery, which supplies the left atrium and the posterior walls of the
left ventricle.
The right coronary artery course to the right side of the heart, where it also divides
into two branches: the marginal artery, which serves the myocardium of the lateral
right side of the heart and the posterior interventricular artery, which runs to the heart
apex and supplies the posterior ventricular walls. Near the apex of the heart, this
artery merge or anastomoses with anterior interventricular artery, together, the
branches of the right coronary artery supply the right atrium and nearly all the right.
The arterial supply of the heart varies considerably.

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After passing through the capillary bed of the myocardium, the venous blood is
collected by the cardiac veins, whose paths roughly follow those of the coronary
arteries. These veins join together, to form an enlarged vessel called the coronary
sinus, which empties the blood into the right atrium. The coronary sinus is obvious on
the posterior aspect of the heart. The sinus has three large tributaries: (a) the great
cardiac vein in the anterior interventricular sulcus; (b) the middle cardiac vein in the
posterior interventricular sulcus; and (c) the small cardiac vein, running along the
hearts right inferior margin. Additionally, several anterior cardiac veins empty
directly into the right atrium anteriorly.

CONGENITAL HEART DEFECTS

Originating during embryonic development, congenital heart defects can seriously impair
heart function. Many such defects are caused by infections such as rubella, also called German
measles or medications of pregnancy when the embryonic heart is developing. These defects
impair patients ability to withstand exertion and can be life threatening. They are as follows;
COARCTATION OF THE AORTA - a stenosis(narrowing) of the aorta, causes the left
ventricle to work excessively hard to force blood flow through the aorta, thereby causing an
enlargement of the left ventricle.
PATENT DUCTUS ARTERIOSUS – the ductus arteriosus fails to close at birth and blood is
recycled through the lungs i.e there is a left to right shunt caused by a patent between the
concavity of the arch of the aorta and the region of bifurcation of pulmonary trunk. After
several years if the ductus is not surgically closed, the entire heart becomes greatly enlarged,
due to the increased pumping needed to maintain systemic blood flow while pumping two to
three times the normal amount of blood through the lungs.
ATRIAL SEPTAL DEFECT – an opening in the interatrial septum often caused by failure of
the foramen ovale to close. Like the ductus arteriosus, the foramen ovale allows blood to
bypass in a fetus. At birth a fibrous tissue grows to seal it off.
VENTRICULAR SEPTAL DEFECTS: an opening in the interventricular septum allowing
blood to flow from the right to the left ventricle. If the defect is not corrected by open heart
surgery, the walls of the right ventricle becomes as thick as the left ventricle.
TETRALOGY OF FALLOT – four simultaneous heart defects. The defects include;
(i) The aorta originating from the right or both ventricles
(ii) Pulmonary artery stenosis
(iii) An interventricular septal defect
(iv) An enlarged right ventricle
An infant with the defect is sometimes called a “blue baby” because blood is poorly
oxygenated and the skin appears blue. Surgical procedure can correct these multiple defects.

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 CARDIAC OUTPUT(CO)
Cardiac output is the amount of blood pumped out by each ventricle in one minute.
It is the product of heart rate(HR) and stroke volume(SV).
Stroke volume is defined as the volume of blood pumped out by one ventricle in each
heartbeat. Using the normal resting value for heart rate( 75 beats/min) and stroke
volume(70ml/beat), the average adult cardiac output can be computed;
C.O = HR × SV
C.O = 75beats/min × 70ml/beat
C.O = 5250ml/min
C.O = 5.25L/min
The cardiac output varies directly with HR and SV. Thus the CO increases when the
stroke volume increases or the heart beats faster or both and decrease when both or
either of the factors decrease.

THE CONDUCTING SYSTEM OF THE HEART

The heart has an intrinsic system whereby the muscle is stimulated to contract without
the need for nerve supply from the brain. However, this system can be stimulated or
depressed by nerve impulses initiated in the brain. There are small groups of
specialized neuromuscular cells in the myocardium which initiate and conduct
impulses of contraction over the heart muscle.

The Conducting System of the Heart

• The Sinoatrial node( SA node): this small mass of specialized cells is situated
in the right atrium, near the opening of the superior vena cava. It is described
as the “pace maker” of the heart because it initiates impulses which stimulate
the contraction of the myocardium irrespective of the nervous supply from the
central nervous system.

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 • The Atrioventricular node (AV node): this is a mass of neuromuscular tissue
situated in wall of the atrial septum near the atrioventricular valves. It is
capable of initiating impulse of contraction but at a slower rate than the SA
node, if there is no stimulation by the nervous system.
• The Atrioventricular bundle(AV bundle): this consists of a mass of specialized
fibres which originates from the atrioventricular node and passes downward
in the septum that separates the right and left ventricles. This bundle of
fibres(bundle of His) divides into two branches, one going to each ventricle.
The branches further break up into a network of fine filaments or fibres called
the fibres of Purkinje. The AV bundle and the Purkinje fibres carry the impulse
of contraction from the AV node to the myocardium of the ventricles.

CARDIAC CYCLE
The heart acts as a pump and its action consists of a series of events known as the
cardiac cycle. In a human being, when the heart is beating normally the cardiac cycle
occurs 74 times per minute. Thus, each cycle lasts for 0.8 second. The cardiac cycle
consists of;
a. Atrial systole – contraction of atria
b. Atrial systole – contraction of the ventricles
c. Complete cardiac diastole – relaxation of the atria and ventricles.

The superior and inferior vena cava pour deoxygenated blood into the right atrium at
the same time as the four pulmonary veins pour oxygenated blood into the left atrium.
The sinoatrial node emits an impulse of contraction. This stimulates the contraction of
the myocardium of the right atrium which spread over them pushing blood through
it into the ventricles( atrial systole, 0.1second).

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When this wave of contraction reaches the atrioventricular node, it is stimulated to
emit impulses of contraction, which spread to the ventricular muscle via the
atrioventricular bundle and sweeps upward from the apex of the heart and pushes the
blood into the pulmonary artery and the aorta(ventricular systole, 0.3 seconds).
After the contraction of the ventricles, the heart rest for 0.4 second and this period is
called the complete cardiac diastole. After the complete cardiac diastole the cycle
begins again with atrial systole.

BLOOD PRESSURE
Blood pressure is the force or pressure that the blood exerts on the walls of the blood
vessels. Systemic arterial blood pressure maintains the essential flow of blood into and
out of the organs of the body.
Keeping blood pressure within the normal limits is very important. If it becomes too
high, blood vessels can be damaged, causing clots or bleeding from sites of blood
vessel rupture. And if it becomes too low, blood flow through tissue beds may be
inadequate. This is particularly dangerous for organs like heart, brain or kidneys.
Blood pressure varies according to the time of day, the posture, gender and age of the
individual. Blood pressure falls at rest and during sleep. It increases with age and is
usually higher in women than in men.
SYSTOLIC BLOOD PRESSURE
When the left ventricle contracts and pushes blood into the aorta, the pressure
produced within the arterial system is called the systolic blood pressure. In other
words, it is the maximum pressure exerted in arteries during systole of heart. In adult
it is about 120mmHg or 16kPa.
DIASTOLIC BLOOD PRESSURE
When the heart is resting following the ejection of blood, the pressure within the
arteries is much lower and is called diastolic blood pressure. In other words, it is the
minimum pressure exerted in the arteries during diastole of the heart. In an adult this
is about 80mmHg or 11kPa.
The difference between systolic and diastolic blood pressure is the pulse pressure. The
arterial blood pressure(pressure exerted by blood on wall of arteries) is measured with
a sphygmomanometer and is usually expressed with the systolic pressure written
above and the diastolic pressure below.
BP= 120/80mmHg or 16/11kPa

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 FACTORS DETERMING BLOOD PRESSURE
Blood pressure is determined by cardiac output and peripheral resistance. Change is
either of these parameters tends to alter systemic blood pressure.
• Cardiac Output: is determined by stroke volume and heart rate. An increase in
cardiac output raises both systolic and diastolic pressures. And increase in
stroke volume increases systolic pressure more than it does to diastolic
pressure.
• Peripheral Resistance: is the resistance offered to the blood flow at the
periphery. Resistance is offered at arterioles, which are called the resistant
vessels. Diastolic pressure is directly proportional to peripheral resistance.
• Blood Volume: blood pressure is directly proportional to blood volume. Blood
volume maintains the blood pressure through the venous return and cardiac
output.
• Autoregulation: systemic blood pressure rises and falls constantly, according
to levels of activity, body position, etc. However, the organs of the body are
capable of adjusting blood flow and blood pressure in their own local vessels
independently of systemic pressure. This property is called autoregulation, and
protects the tissues against swings in systemic pressures.

PULSE
Arterial pulse is defined as the pressure changes transmitted in the form of waves
through arterial wall and blood column from heart to periphery. The pulse can be felt
with gentle finger pressure in a superficial artery when its wall is distended by blood
pumped from the left ventricle during contraction(systole). Each contraction of the left
ventricle forces about 60–80 millilitres of blood through the already full aorta and into
the arterial system. The aortic pressure wave is transmitted through the arterial
system and can be felt at any point where a superficial artery can be pressed firmly
but gently against a bone. The number of pulse beats per minute normally represents
the heart rate and varies considerably in different people and in the same person at
different times.
Information that may be obtained from the pulse includes:
• The rate at which the heart is beating
• The regularity of the heartbeat – the intervals between beats should be equal
• The volume or strength of the beat – it should be possible to compress the
artery with moderate pressure, stopping the flow of blood; the

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 compressibility of the blood vessel gives some indication of the blood
pressure and the state of the blood vessel wall.
• The tension – the artery wall should feel soft and pliant under the fingers.
PULSE POINTS
Usually, pulse is palpated on the radial artery because it is easily approachable and
placed superficially. However, arterial pulse can be felt in different areas on the body.
These areas are called pulse points.a of palpation
➢ Temporal pulse: Over the temple, in front of ear on superficial temporal artery
➢ Facial pulse: on facial artery at the angle of jaw
➢ Carotid pulse: in the neck along anterior border of sternocleidomastoid muscle
on common carotid artery.
➢ Axillary pulse: in axilla on axillary artery.
➢ Brachial pulse: in cubital fossa along medial border of biceps muscle on brachial
artery.
➢ Radial pulse: over the thumbside of wrist between tendons of brachioradialis
and flexor carpi radialis muscles on radial artery.
➢ Ulnar pulse: over the little fingerside of wrist on ulnar artery
➢ Femoral pulse: in the groin on femoral artery
➢ Popliteal pulse: behind knee, in the popliteal fossa on popliteal artery
➢ Dorsalis pedis pulse: over the dorsum of foot on dorsalis pedis artery
➢ Tibial pulse: over the back of the ankle, behind medial malleolus on posterior
tibial artery

Formation and transmission of pulse wave depends upon the elasticity of blood
vessels. Thus, when the walls of the arteries are more distensible, the pressure rise is
less and so the transmission of pulse is less. When the arterial wall loses its elastic
property and becomes rigid as in old age, the pressure rise is more and the
transmission of pulse is also more.
Pulse is not transmitted to capillaries because capillaries are devoid of elastic tissues.
Venous pulse is defined as the pressure changes transmitted in the form of waves from
right atrium to veins near heart. Venous pulse is observed only in larger veins near
the heart such as jugular vein. Venous pulse recording is used to determine the rate of
atrial contraction, just as the record of arterial pulse is used to determine the rate of
ventricular contraction. And also, many phases of cardiac cycle can be recognized by
means of venous pulse tracing.

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 HEART SOUND
Heart sounds are the noises gathered by the beating heart and the resultant flow of
blood through it. The act of listening to sounds within the body is called
auscultation(auscultare meaning to listen), and it is usually done with a stethoscope.
The sound of the heartbeat comes primarily from turbulence in blood flow created by
the closure of valves, not from the contraction of the heart muscle. The turbulence in
the blood flow creates sounds referred to as Korotkoff’s sound. The first heart sound
which can be described as a ‘Lubb’ sound, is louder and a bit longer than the second
sound. The lubb is the sound created by the closure of the atrioventricular valves at
the commencement of the ventricular systole.
The second sound, which is not as loud is shorter than the first, can be described as a
‘Dupp’ sound. Dupp is the sound created as the semilunar valves close toward the
end of the ventricular systole. A pause between second sound and the first sound of
it next cycle is about two times longer than the pause between the first and second
sound of each cycle. Thus the cardiac cycle can be heard as a lubb, dupp, pause; dupp,
pause.
When a sound is heard before or after the normal heart tones, this may represent a
heart murmur or some other abnormality.
Heart sounds provide valuable information about the valves( of the heart). Beside the
lubb- dupp, some persons also have a third or fourth heart sound. Because this sound
may suggest the cantering of a horse, the term “gallop rhythm” is used to describe
these extra heart sounds, which are often associated with heart disease. Other
abnormal sounds include “snaps”, “knocks”, “rubs” and “clicks”. A heart murmur,
therefore is an abnormal sound that consists of a slow noise that is heard before or
after the lubb- dupp, or that may mask the normal heart sounds.

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