Cardio vascular and Lymphatic system structure

CIRCULATORY
& LYMPHATIC
SYSTEM

INTRODUCTION
The cardiovascular system is sometimes called the
circulatory system. It consists of the heart,
which is a muscular pumping organ, and a closed
system of vessels called arteries, veins, and
capillaries.
Blood contained in the circulatory system is
pumped by the heart around a closed circle or
circuit of vessels as it passes again and again
through the various circulations of the body.

CONNECTION
BETWEEN HEART
AND BLOOD
VESSELS

HEART
External Feature
The human heart is a four-chambered, conical muscular organ, pyramid shaped,
sized roughly like a person’s closed fist. It lies in the mediastinum, or middle
region of the thorax, just behind the body of the sternum between the second
through the sixth ribs. Approximately two-thirds of the heart’s mass is to the left
of the midline of the body and one third to the right.
Size and Shape of the Heart
At birth, the heart is said to be transverse (wide) in type and appears large in
proportion to the diameter of the chest cavity. Between puberty and 25 years of
age the heart attains its adult shape and weight—about 300 grams is average for
the male and 225 g for the female. Its approximate dimensions are length 12 cm,
width 9 cm, and depth 6 cm.

WHERE IS YOUR HEART LOCATED?
It sits slightly behind and to the left of your sternum (breastbone), which is in
the middle of your chest. Your heart is slightly on the left side of your body. It
sits between your right and left lungs. The left lung is slightly smaller to make
room for the heart in your left chest.
Relations:
Anteriorly: the body of the sternum, and adjoining costal cartilages; left lung,
and pleura (apex)
Posteriorly: oesophagus, descending thoracic aorta, azygos, hemiazygos
veins, and thoracic duct
Superficially : bifurcation of the main pulmonary trunk
Inferiorly: diaphragm
Laterally: lungs, pleura

DIFFERENT LAYERS OF
PERICARDIUM
COVERINGS OF THE HEART
Structure of the Heart Coverings
The heart has its own covering, a
fibroserous sac, called the pericardium.
The pericardium enclosed the heart and
the root of great vessels. The sac itself is
made of tough white fibrous tissue but is
lined with smooth, moist serous
membrane. The fibrous sac attaches to
the large blood vessels emerging from
the top of the heart but not to the heart
itself.

Paricardial Cavity
Pericardium fits loosely around the heart, with a slight space between
the visceral layer adhering to the heart and the parietal layer adhering to
the inside of the fibrous sac. This space is called the pericardial space. It
contains (10–15 mL) of lubricating fluid secreted by the serous
membrane and called pericardial fluid.

SURFACES OF THE HEART
Sternocostal Surface
Diaphragmatic Surface
Base
Anterior (or sternocostal surface ) – Right ventricle.
Posterior (base of the pyramid) – Left atrium.
Inferior (or diaphragmatic surface ) – Left and right ventricles
APEX
It is formed by the left ventricle is directed downward and
toward the left. It lies at the level of the fifth left intercostal space, 9
cm (3.5 inches) from the midline.

THREE SURFACES
Sternocostal surface: Is formed by right atrium, right ventricle, left auricle
and left ventricle.
Left surface: Is formed by left auricle and left ventricle.
Diaphragmatic surface: 2/3rd
is formed by left ventricle and 1/3rd
by right
ventricle.
Posterior surface/Base: It is quadrilateral in shape.
2/3rd
of base is formed by posterior surface of left atrium and
1/3rd
by right atrium.
It lies opposite to T5-T8 vertebra in supine position.

Structure of the Heart
Layers (Walls) of the Heart
Epicardium
The outer layer of the heart wall is called the epicardium, a name that literally means
“on the heart.” The epicardium is actually the visceral layer of the serous pericardium.
It has two different names: fibrous pericardium and serous pericardium.
Myocardium
The bulk of the heart wall is the thick, contractile, middle layer of especially
constructed and arranged cardiac muscle cells called the myocardium.
Endocardium
The lining of the interior of the myocardial wall is a delicate layer of endothelial tissue
known as the endocardium. Endothelium is the type of membranous tissue that lines the
heart and blood vessels. Endothelium resembles simple squamous epithelium.

CHAMBERS OF THE HEART
The interior of the heart is divided by vertical septa into four cavities, or heart
chambers. The right and left atria, and right and left ventricles. The right atrium
lies anterior to the left atrium and the right ventricle lies anterior to the left
ventricle. The two chambers of the heart, the atria are often called the “receiving
chambers” because they receive blood from vessels called veins. Veins are the
large blood vessels that return blood from various tissues to the heart so that the
blood can be pumped out to tissues again.

The atria alternately relax and contract to receive blood and then push it
into ventricles. Because the atria need not generate great pressure to
move blood such a small distance, the myocardial wall of each atrium is
not very thick.

Right Atria
It forms the right border and parts of the sternocostal surface and base of
heart. The terminal sulcus is a groove on the outer surface of the right
atrium of the heart marking the transition between the sinus venarum
cavarum (which has a distinct embryological origin) and the rest of the right
atrium (which features pectinate muscles on its inner surface) The terminal
sulcus (and crest) indicate the position of the sinoatrial node.
Right Ventricle
The right ventricle communicates with the right atrium through the A
V
orifice and with the pulmonary trunk through the orifice. It receives blood
from right atrium and pumps it to the lungs through the pulmonary trunk.

Left Atrium
The left atrium consists of a main cavity and situated behind the right
atrium. It forms the greater part of the base or the posterior surface of
the heart and the part of left border, left surface and sternocostal
surface.

Left Ventricle
The left ventricle forms the apex, sternocostal surface, and left 2/3 of
diaphragmatic surface. The walls of the left ventricle are three times thicker than
right ventricle.

VALVES OF THE HEART
The heart valves are mechanical devices that permit the flow of blood in one
direction only. Four sets of valves are of importance to the normal
functioning of the heart. Two of these, the AV valves, guard the openings
between the atria and the ventricles (AV orifices). The AV valves are also
called tricuspid/bicuspid valves. The other two heart valves, the semilunar
(SL) valves, are located where the pulmonary artery and the aorta arise from
the right and left ventricles, respectively.

BLOOD SUPPLY OF HEART AND VENOUS DRAINAGE OF HEART

BLOOD SUPPLY TO HEART
The heart is supplied by two coronary arteries:
LEFT MAIN CORONARY ARTERY carries 80% of the flow to the heart muscle. It is a
short artery that divides into two branches.
Left anterior descending artery that supplies anterior two-thirds of the inter-
ventricular septum and adjoining part of the left ventricular anterior wall.
Circumflex coronary artery that supplies blood to the lateral and posterior portions
of the left ventricle.
RIGHT CORONARY ARTERY: branches supply the right ventricle, right atrium, and
left ventricle's inferior wall.

NERVE SUPPLY TO HEART
The main control of the heart resides with the medulla oblongata. There is an
area called the cardioacceleratory centre, or pressor centre, in the upper part of
the medulla oblongata, and an area called the cardioinhibitory centre, or
depressor centre, in the lower part.
Together they are called the cardioregulatory centre, since they interact to
control heart rate, etc.
The sympathetic nervous system acts on the sinoatrial node, speeding up the
depolarisation rate, and therefore increasing the heart rate.
The parasympathetic system works in reverse in order to slow the heart rate
down.
The heart itself has a natural pacemaker, the sinoatrial node, which does not need
a nervous supply to function.

CONDUCTION SYSTEM OF THE
HEART
The conducting system of the heart consists of specialized cardiac
muscles present in the sinuatrial node, A
V node, AV bundle and its
left and right branches and the subendocardial plexus of purkinje
fibers.
 The sinoatrial node (SA Node)
 Atrioventricular node (AV Node)
 Atrioventricular bundle (Bundle of His)
 Purkinje fibers

Sinoatrial Node
The sinoatrial node (SA node or pacemaker) located in the right atrial
wall in the upper part of the sulcus terminalis near the opening of the
superior vena cava.
Atrioventricular Node
The atrioventricular node (AV node) is a small mass of special cardiac
muscle tissue, placed on the lower wall of the atrial septum just above
the attachment of the septal cusp of the tricuspid valve.

CONDUCTING SYSTEM OF
THE HEART
The atrioventricular bundle (AV bundle or
bundle of His) is a bundle of special cardiac
muscle fibers that originate in the AV node
and extend by two branches down the two
sides of the interventricular septum.
Purkinje Fibers
The Purkinje fibers form a subendocardial
plexus. The LBB divides into anterior and
posterior branches and the RBB right
bundle branch continues with the fibers of
the Purkinje plexus.

ARTERIAL AND VENOUS SYSTEM
The blood and lymphatic vessels that circulate through the body make
up the vascular system, also known as the circulatory system.
The arteries and veins transport blood throughout the body, providing
the tissues with oxygen and nutrition and removing waste products from
the cells.
Lymphatic fluid is transported through lymph vessels (a clear,
colourless fluid containing water and blood cells).
By filtering and removing lymph from every area of the body, the
lymphatic system aids in preserving and defending the body’s fluid
environment.

Types of Blood Vessels
Artery
An artery is a vessel that carries blood away from the heart. After birth,
all arteries except the pulmonary artery and its branches carry
oxygenated blood.
Vein
A vein is a vessel that carries blood toward the heart. All of the veins
except the pulmonary veins contain deoxygenated blood.
Capillaries
These are the microscopic vessels that carry blood from small arteries to
small veins, that is, from arterioles to venules.

LYMPHATIC TISSUE
Lymph is formed from plasma (the liquid
part of blood without the cells). The
nutrients required to “feed” cells throughout
the body are carried by the plasma. Plasma
must ooze into the tissues through
capillaries, the smallest blood arteries, in
order to reach the cells.

SECTIONS OF THE LYMPHATIC SYSTEM
There are two distinct sections of the lymphatic system.
First section:
The bone marrow
The thymus Gland
Second Section:
Organs and tissues are a home for immune system cells. If immune system cells come
into contact with invading organisms in any of the following locations, an
immunological response may be set off.
Lymph nodes
The spleen
The tonsils and adenoids
Mucosa-associated lymphoid tissue

VEINS USED FOR INTRAVENOUS INJECTIONS
• Forearm and arm
Cephalic vein
Basilic vein
Medial cubital vein
Medial basilic vein
Accessory cephalic vein
Cephalic vein
• Veins in hand
• Basilic vein
• Dorsal venous network
• Dorsal metacarpal vein
VEINS USED FOR INTRAVENOUS
INJECTIONS

CLINICAL ANATOMY
The fossa ovalis is a shallow depression, which is the site of the
foramen ovale in the fetus.
Cardiac tamponade is acute heart failure due to compression of heart
by a large or rapidly developing effusion.
Vascular lesion of the heart can cause a variety of arrhythmias.

PHYSIOLOG
Y
CHAPTER 4
CIRCULATORY
&
LYMPHATIC
SYSTEM

INTRODUCTION
The human circulatory system consists of four major
components; blood, blood vessels, the heart and the neural
regulatory centres in the brain. The blood acts as a
transporting medium, the blood vessels are the system of
conduits which transport blood to all parts of the body, the
heart acts as a pump and generate the major driving force
of blood flow through the vessels, and the regulatory
centres control the various activities of the circulatory
system.

THE DIFFERENT COMPONENTS
OF HUMAN CIRCULATORY
SYSTEM
Purpose of the Cardiovascular
System
The cardiovascular system is
responsible for maintaining this
blood flow. By the contractile
action of the heart, a substantial
amount of pressure is created
within the circulatory system,
that ensures adequate blood flow
to different organs for efficient
exchange of gases, fluid,
electrolytes, large molecules
between the blood and cells.

HEART
Location
The heart is a cone shaped hollow muscular organ. It is located in the thoracic
cavity in the middle mediastinum between the lungs. It is oriented obliquely,
more towards the left. The sternum and the ribs lie in the front and the thoracic
spinal column lies behind the heart and protects heart from physical trauma.

Structure
The heart has four chambers. The two small upper chambers are called left and
right atria and two bigger lower chambers are called right and left ventricles.
There is complete separation of all four chambers; two atria are separated by the
interatrial septum and the two ventricles are separated by the interventricular
septum.
Atrium receive the blood returning to heart through veins and get passively
filled.
Ventricles pumps out the blood from heart into the arterial system.
Blood moves from atria to the ventricles through openings called
atrioventricular orifices.
The openings between left ventricle and the aorta and the right ventricle and
pulmonary artery are also guarded by two other valves called semilunar or SL
valves. They prevent backflow of blood from arteries to the ventricles.

POSITION OF THE HEART IN THORACIC CAVITY

FUNCTIONS OF THE
HEART
Pumping Action of the Heart
The heart is a muscular pump and occupies the central position in the human
cardiovascular system Almost 90% of the heart is composed of cardiac muscle.
The heart contains pacemaker tissues that generates electrical impulse which act as
the stimulus for heart muscle contraction. For this reason, the fetal heart starts beat
even without neural stimuli.
The cardiac muscles of the ventricles contract to generate force, which major driving
force for distributing the blood throughout the body and maintains blood pressure.

Endocrine Function
The heart muscles secrete certain proteins called cardiokine, the most
important of which is called atrial natriuretic factor (ANF). This has
natriuretic and vasodilator effect. They are secreted when atrial
muscles are stretched by volume overload.

PRINCIPLES OF CIRCULATION
Blood circulates through the heart in a definite way. The circulatory pattern of
blood through heart shows that blood always flows from atrium to the ventricle.
The right heart (comprising the right atrium and the right ventricle) is concerned
with the flow of deoxygenated blood. The left heart (comprising the left atrium
and the left ventricle) is concerned with the flow of oxygenated blood. The
continuous flow of deoxygenated and oxygenated blood through the right and left
heart respectively is called double circulation.

Pulmonary Circulation
The right atrium receives deoxygenated blood via superior and inferior vena
cava. When the ventricles relax, the blood moves into the right ventricle. When
the right ventricle contracts, the blood is pumped into the pulmonary artery. Next
blood flows across the lungs, it releases carbon dioxide and receives oxygen
from lung alveoli, and returns to the left atrium by pulmonary veins as
oxygenated blood. This circulation from right ventricle to left atrium is called the
Pulmonary or Lesser or Central circulation

Systemic Circulation
The oxygenated blood that returns to left atrium, moves to left ventricle and
when the left ventricles contracts, the blood is forced into the aorta and circulate
into the whole body, via systemic arteries and supply oxygen to all tissues.
Finally, the blood returns back to the right atrium via the superior and inferior
vena cava as deoxygenated blood and moves into right atrium. This circulatory
pattern from left ventricle to right atrium is called the Systemic or Peripheral or
Greater circulation.

HEMODYNAMIC PRINCIPLES
The blood flow is a function of pressure gradient and resistance.
This is similar to the ohms law calculated for current flow. More the pressure
gradient more the flow and vice versa and more the resistance, less the flow.
The pressure gradient is the difference between the mean arterial pressure
(MAP) which is the pressure at the beginning of the aorta (about 100 mmHg)
and the central venous pressure (CVP) which is the pressure near the terminal
portion of the inferior vena cava (about 0 mmHg).
The flow represents the amount of blood ejected from the heart which is cardiac
output.
The resistance denotes the resistance offered by the systemic arterioles.
Flow (cardiac output) = Pressure gradient × 1/Resistance Or, Pressure gradient
(MAP – CVP) = Cardiac output × Systemic vascular resistance

CORONARY CIRCULATION (BLOOD SUPPLY
TO THE HEART)
The heart is the most metabolically active organ, with the highest
oxygen consumption per mass. The coronary circulation, which is
responsible for delivering blood to the myocardium and accounts for
about 5% of cardiac output, meets this demand for oxygen.
The heart or more specifically the heart muscles are supplied by two
main arteries that come out as the first two branches from the aorta.
They are known as left and right coronary arteries. These arteries
subdivide into smaller coronary arteries which supplies blood to the
myocardium

Coronary Blood Vessels
The left and right coronary arteries are the first branches of the aorta, and they
originate at the base of the ascending aorta. The right coronary artery follows the
coronary sulcus (sulcus, which demarcates the junction of the atria and ventricle)
and gives off branches that supply the right atrium, ventricles, parts of the
conducting system and descends posteriorly between the two ventricles as the
posterior inter ventricular branch, supplying the interventricular septum.
Driving Pressure in Coronary Circulation
In coronary circulation the blood flows from the aorta to different coronary
arteries, and then back to the right atrium. Therefore, the pressure difference
between the right atrium and the aorta is the major determining factor of the
coronary blood flow.

Factors Affecting Coronary Blood Flow
Hypoxia induced increased coronary blood flow
Neural factors induced increased coronary blood flow

PULMONARY
CIRCULATION
The lungs have three circulations—pulmonary, bronchial and lymphatic.
Pulmonary Circulation
Pulmonary artery arises from the right ventricle and divides into right and left
pulmonary arteries which convey deoxygenated blood to the right and left lung,
respectively.
Bronchial Circulation
Bronchial circulation constitutes two left and one right bronchial arteries that
arise from the descending thoracic aorta. They supply oxygenated blood to lung
tissues and large and small bronchi of the lungs.

Lymphatic Circulation
Lungs are richly supplied by lymphatics. Lymphatics are present in the walls
of the terminal bronchioles and in all the supportive tissues of the lungs.

HEART MUSCLES
The cardiac muscle cells are striated, involuntary, short and branched structures.
The cells have one, centrally placed nucleus and a sarcoplasmic reticulum (SR)
associated with the T tubules. The T tubules are extensions of the muscle
membrane that moves deep into the cell and provides extracellular calcium to
the muscle cells during contraction.
The muscle cells are interconnected with each other. The connection between
two adjacent muscles appears as dark stained areas under microscope and
known as intercalated disks.

CONDUCTING SYSTEM OF THE
HEART
Conducting system include the following type of tissues:
Sinoatrial Node (SA Node)
This is a small nodal structure located in the right atrial wall near the opening of the
superior vena cava.
Internodal Fibres
Internodal fibres are composed of three branches; the anterior, middle and the posterior
internodal tracts.
Atrioventricular Node (AV Node)
This is a small bundle of muscle fibres at the base of the right atrium, just above the
junction of the atria and ventricles.
His – Purkenji System
This is a bundle system which mainly conducts impulse from AV node to
the ventricles. It is composed of three different fibre system.

Pacemaker Potential
The pacemaker potential is the gradual change in the resting membrane potential
of the pacemaker cells of heart which leads to the generation of action potential.
EFFECTS OF SYMPATHETIC AND PARASYMPATHETIC STIMULATION
ON

Electrocardiogram
The heart muscles are always subjected to electrical stimulation. The body tissues
and fluids are conductor of electricity; therefore, the ongoing electrical activities
of the heart can be recorded by placing suitable electrodes on the skin
surface. This recording, called an electrocardiogram (ECG).

CARDIAC
CYCLE
In a single heartbeat, the heart undergoes
different mechanical events, which
includes contraction and relaxation of its
atria and ventricles. The contraction is
called systole and the relaxation is called
diastole.

Atrial Systole and Diastole
The impulse for cardiac muscle excitation is initiated at the SA node. It is located
in the left atrium. So atrial excitation and contraction is the first event of cardiac
cycle. Given a cardiac cycle time of 0.8 sec, the duration of atrial systole is only
0.1 sec. During atrial systole, the blood from the atria is forced into the ventricles
through the AV valves. Atrial systole is followed by atrial relaxation or diastole
which is about 0.7 sec.

Ventricle Systole
After excitation of the atria, the impulse from the SA node pass to A
V
node by internodal fibres and further down to the ventricular muscles
via the His Purkenji system and cause excitation (depolarization) of
ventricular muscle. This leads to ventricular contraction or systole.
Isovolumetric Contraction
With the onset of ventricular systole, the pressure within the ventricle
rises and to prevent backflow of blood from ventricles to the atria, the
AV valves close. This produces the first heart sound.

Rapid Ejection Phase
As the name implies, in this phase, blood is ejected rapidly from
ventricles into the arteries. After isovolumetric phase, ventricular
contraction continues, there is further rise in intraventricular pressure.
Slow Ejection Phase
With rapid ejection, as much of the blood volume is ejected out, the
intraventricular pressure falls, and now, blood continues to be ejected
slowly for a longer period. This phase is therefore called slow ejection
phase. However, the volume of blood ejected in this phase is less than
the volume ejected in rapid ejection phase.

Ventricular Diastole
Given a cardiac cycle time of 0.8 sec, the ventricular diastolic time is 0.5 sec and
it comprised of five different phases, each marked with different events. These
phases are as follow:
Protodiastole
Isometric Relaxation Phase
1st Rapid Filling Phase
Slow Filling or Diastasis
Last rapid Filling Phase

HEART SOUNDS
Mechanical activities during cardiac cycle produces four different sounds within
the heart that are termed as heart sounds, each having a different characteristic
feature and significance. These sounds are studied to detect cardiac problems.
1. First Heart Sound
This is produced by the vibration caused by the closure of the AV valves at the
onset of ventricular systole during isovolumetric contraction. It sounds like the
spoken word LUBB. It can be auscultated over the mitral and tricuspid area by a
stethoscope.

2. Second Heart Sound
This is produced by the vibration caused by the closure of the semilunar valves at
the onset of ventricular diastole just at the end of Protodiastole phase. It sounds
like the spoken word DUBB. It is best auscultated over the aortic and pulmonary
area.
3. Third Heart Sound
It is produced during the first rapid filling phase of ventricular diastole, due to
rushing of blood from atria to the ventricles.
4. Fourth Heart Sound
It is produced by the vibration caused by the second rapid rush of blood from atria
to the ventricles during last rapid filling phase of ventricular diastole. It is
normally not audible, but can be heard when atrial pressure is high or when the
ventricles are stiff and noncompliant, as occur in ventricular hypertrophy.

CARDIAC OUTPUT AND STROKE VOLUME
Cardiac output is the total amount of blood ejected from each ventricle per
minute. The normal cardiac output is about 5 litters. Cardiac output is of immense
physiological importance. It determines the amount of the blood flowing in the
circulatory system and the blood supply to the organs.

Factors Affecting Cardiac Output
Two major physiological determinants that directly affect cardiac output are the
stroke volume and heart rate. The amount of blood ejected from each ventricle in
each beat is called stroke volume (SV) and the heart rate is the number of heart
beats per minute. Therefore, multiplying the stroke volume with the number of
heart beat per minute, gives the total amount of blood ejected from each ventricle
of the heart in one minute, which is cardiac output (CO).

Factors affecting stroke volume
Myocardial Contractility
Contractility refers to the contracting capacity of the ventricular muscles. More
the power of contraction, more blood will be ejected from the heart with each
stroke and more will be the stroke volume and this will increase the cardiac
output.
Neural factors
Hormonal factors
Ionic factors
Drugs

Venous Return
When the venous return is more, the ventricles get more filled with
blood during diastole. This increases the end diastolic volume. More
ventricular filling stretches the ventricles with more elongation of
ventricular muscle fibres. As the ventricular muscle fibres get stretched,
they contract with more force, this ejects more blood from ventricles, or
in other words, the stroke volume is increased.

HEART RATE
Heart rate refers to the number of times the heart beats in
one minute. The normal range of heart rate varies between
60–90 beats/min with an average of 75 beats/min. Heart
rate above 100 beats/min is known as tachycardia and
heart rate below 60 beats/min is known as bradycardia.
The normal heart rate follows a rhythmic pattern and any
change in the rhythmic pattern is known as arrhythmia

Conditions Decreasing HR
Athletes have decreased heart rate due to increased capacity of
the heart
Emotional conditions like shock depression grief decreases heart rate
Heart rate increases during inspiration and
decreases during expiration this phenomena is known as sinus
arrhythmia

BLOOD PRESSURE
Definition
The term blood pressure in cardiovascular physiology
indicates the arterial blood pressure, i.e., the pressure
within the arteries. It is defined as the lateral pressure
exerted by the moving column of blood on the wall
of the arteries

 Systolic Blood Pressure
This is the maximum pressure in the arteries obtained during systole. The normal range
of systolic pressure is 90–140 mm of Hg.
 Diastolic Blood Pressure
This is the minimum pressure in the arteries obtained at the end of diastole. The normal
range of diastolic pressure is 60–90 mm of Hg.
 Pulse Pressure
This is the obtained as the difference between systolic and diastolic blood pressure. The
normal pulse pressure is about 40 mm of Hg.
 Mean Arterial Blood Pressure
Mean arterial blood pressure indicates the pressure in the arterial system during
the whole range of systolic and diastolic phase of the heart.

PULSE
With each stroke volume, as the blood is forced
into the aorta and subsequently in the arteries a
pressure wave that travels along the arteries. As
the arterial walls contain elastic tissues, the wave
causes alternate expansion and contraction of the
arterial wall, which is called pulse.

Examination of the Pulse
Some common areas where arterial pulsations
can be felt are as follows:
Temporal arterial pulse, Carotid arterial
pulse,
Radial arterial pulse, Femoral arterial pulse,
Popliteal arterial pulse.
COMMON
PERIPHERAL SITES OF
PULSE ASSESSMENT

CARDIOVASCULAR HOMEOSTASIS IN EXERCISE
Redistribution of Blood Flow in the Body with Increase in the Skeletal
Muscle Blood Flow
During strenuous exercise muscle blood flow increase up to 20 times. This is
called exercise hyperaemia.
Increased Cardiac Activity
During exercise, the peripheral stimuli from the exercising muscles and
proprioceptors present in the muscles and joints are conveyed to the medullary
sympathetic vasomotor center, which in turn increases all cardiac activities
Decrease in Blood Volume
Blood volume is decreased in exercise because with increase in hydrostatic
pressure more filtration of fluid occurs in the capillaries.

DISORDERS OF THE
HEART
Acute Pericarditis
This is inflammation of the pericardium, sometimes due to infection, radiation
therapy, or connective tissue disease, causing pain and friction rub.
Cardiac Tamponade
Compression of the heart by an abnormal accumulation of fluid in the pericardial
cavity, interfering with ventricular filling; may result from pericarditis.
Cardiomyopathy
This is disease of the myocardium. There may thinning of the heart wall, or
thickening of the interventricular septum which can cause dilation and failure of
the heart.

Infective Endocarditis
Inflammation of the endocardium, usually due to infection, by streptococcus and
staphylococcus bacteria.
Myocardial Ischemia
This is inadequate blood flow to the myocardium, usually because of coronary
atherosclerosis; can lead to myocardial infarction.
Septal Defects
Abnormal openings in the interatrial or interventricular septum, resulting in
blood flow between the atrium, or blood from the left ventricle returning to the
right ventricle.

Cardiac Failure
This is the inability of the heart to pump blood in sufficient need to meet
the body’s demand. Various cause of cardiac failure include; decreased
cardiac contractility due to reduced coronary blood flow, valvular
damage or dysfunction, external compression of the heart due to
pericardial effusion, cardiomyopathy and hypertension.
Hypertension
High blood pressure, is commonly considered to be a chronic high
resting blood pressure with systolic above 140 mmHg and diastolic
above 90 mmHg. Hypertension is the major cause of heart failure,
stroke, and kidney failure.

Aneurysm
An aneurysm is a weak point in a blood vessel or in the heart wall that
forms a thin-walled, bulging sac that pulsates with each beat of the heart
and may eventually rupture.
Circulatory Shock
Cardiovascular homeostasis is all about maintaining adequate blood
flow to different organs according to their needs. to maintain supply of
nutrients and removal of wastes to and from the cells. The failure to
maintain adequate flow is referred to a circulatory shock.

STRUCTURE AND FUNCTIONS OF THE VASCULAR
SYSTEM
Structure of the Blood Vessels
The three major categories of blood vessels in the circulatory system are the
arteries, veins and the capillaries. There are different categories of arteries and
veins. All types of arteries and veins have the same basic three-layered structure;
an inner tunica intima, middle tunica media and outer tunica adventitia.
Function of the Blood Vessels
Function of Arteries
The main function of the arteries is to carry blood away from heart. There are
different arteries each type has a specific function. The largest arteries are aorta
and large arteries. They arise from heart and when the ventricles contract, the
heart is ejected into these arteries. Therefore, these arteries have to withstand
great force.

The content of elastic tissues in their walls make these arteries distensible. With
each heart beat as blood is pumped out in these vessels, the wall of the vessels
expands to accommodate the blood during systolic flow without much rise in
pressure.
In the vascular tree, the branching of large arteries form smaller arteries, which
by further branching produce arterioles and metarterioles with progressively
smaller diameter. The smaller arteries and arterioles and meta-arterioles have
smooth muscles within their walls which can constrict and alter the flow of
blood through these arteries.

Functions of Capillaries
Four different forces, called starlings forces that act across the capillaries,
determine the net movement of substances, to and from the cell to blood and vice
versa. These forces are:
Hydrostatic pressure of the capillaries contributed by the blood
pressure (favours filtration)
Osmotic pressure of the capillaries contributed by the plasma proteins (favours
reabsorption)
Hydrostatic pressure in the interstitial space (favours reabsorption).
Osmotic pressure in the interstitial space (favours filtration)

Functions of Veins
They have large diameter and thin wall and lack elastic tissues. They are
supplied with valves which permits one way flow of blood through the
veins and assists the blood to flow towards the heart.
Small veins that arise by the unification of the capillaries are called
venules. Venules are supplied by nerve and by contraction they provide
post capillary resistance, which can increase hydrostatic pressure in the
capillaries and increase filtration.
Venules unite to form veins and veins unite to form large veins and vena
cava, which returns blood to heart.

LYMPHATIC CIRCULATION
The lymphatic circulation is concerned with the flow of lymph and
consists lymph, lymph vessels, and lymph nodes, lymph organs and lymphoid
tissues.
Lymph
Lymph is a clear watery fluid, similar in composition to plasma, but does not
contain plasma proteins. During capillary exchange, at arterial end, fluid move
out of the capillaries by filtration.
Lymph Vessels
The smallest lymph vessels are the lymph capillaries. They arise as are blind-end
tubes present in the interstitial spaces (Fig. 26). Like the blood capillaries, they
have an endothelial cell layer, but their walls are more permeable.

Thoracic Duct
It opens into the left subclavian vein in the root of the neck. It drains lymph from
both legs, the pelvic and abdominal cavities, the left half of the thorax, head and
neck and the left arm.
Right Lymphatic Duct
It drains lymph from the right half of the thorax, head and neck and the right arm
into the right subclavian vein.
Lymph Nodes
These are oval shaped nodular structure located along the length of lymph
vessels. They contain reticular and lymphatic tissue. The lymphatic tissue
contains immune and defence cells, including lymphocytes and macrophages.

Lymph Organs
Spleen and thymus are considered as lymph organs. Spleen store blood,
performs phagocytic action and removes ageing or damaged cells from the
bloodstream. The T-and B-lymphocytes present in spleen act against
antigens.

Lymphoid Tissues
Lymphoid tissues are also known as mucosa-associated lymphoid tissue
(MALT) which are present throughout the gastrointestinal tract, in the
respiratory tract and in the genitourinary tract, all systems of the body
exposed to the external environment.

Cardio vascular and Lymphatic system structure

Cardio vascular and Lymphatic system structure

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Cardio vascular and Lymphatic system structure