Download Blood vessels are of three types: arteries, veins, and capillaries. THE

Q.What is the cardiovascular
system?
The heart is a double pump.
heart arteries  arterioles


Veins  venules  capillaries
The cardiovascular system is composed of :
1-Heart .
2-Blood vessels.
Three type of blood vessels:
1-Arteries.
2-Veins.
3-Capillaries
Special types of arteries are:
1-End arteries . e.g. Central artery of retina ,central artery of the
brain, arteries within the kidney & spleen and coronary arteries of
the heart.
2-Tortuous arteries .e.g. Facial artery , Uterine artery, Splenic artery
and Lingual artery.
Circulatory
system
is
composed of heart and
blood vessels.
Blood
vessels
is
composed of arteries ,veins
and capillaries.
1-BLOOD VESSELS:
Blood vessels are of three types: arteries, veins, and capillaries.
THE ARTERIES:
Arteries transport blood from the heart and distribute it to the
various tissues of the body by means of their branches .
The smallest arteries, <0.1 mm in diameter, are referred to as
arterioles.
The joining branches of arteries is called an anastomosis.
Arteries do not have valves.
Anatomic end arteries are vessels whose terminal branches do not
anastomose with branches of arteries supplying adjacent areas.
Functional end arteries are vessels whose terminal branches do
anastomose with those of adjacent arteries, but the caliber of the
anastomosis is insufficient to keep the tissue live.
Examples for arteries in the body Aorta (ascending, arch,
descending) , innominate ,subclavian, carotid, axillary, brachial,
common iliac, femoral, popliteal, anterior and posterior tibial
Arteries of the body:
THE VEINS:
Veins are vessels that transport blood back to the heart; many of
them possess valves.
The smallest veins are called venules .
The smaller veins, or tributaries, unite to form larger veins, which
commonly join with one another to form venous plexuses.
Medium-size deep arteries are often accompanied by two veins, one
on each side, called venae comitantes.
Veins leaving the gastrointestinal tract do not go directly to the
heart but converge to the portal vein; this vein enters the liver and
breaks up again into veins of diminishing size, which ultimately join
capillary-like vessels, termed sinusoids, in the liver .
A portal system is thus a system of vessels interposed between two
capillary beds.
Examples for veins in the body: Superior and inferior vena cava
,innominate ,subclavian, internal jugular ,axillary and brachial veins
,common iliac, femoral and popliteal veins.
Veins of the body:
THE CAPILLARIES :
They microscopic vessels in the form of a network
connecting the arterioles to the venules .
The Sinusoids resemble capillaries in that they are thinwalled blood vessels, but they have an irregular cross
diameter and are wider than capillaries.
They are found in the bone marrow, the spleen, the liver,
and some endocrine glands.
In some areas of the body, principally the tips of the
fingers and toes, direct connections occur between the
arteries and veins without the intervention of capillaries.
The sites of such connections are referred to as
arteriovenous anastomosis.
CAPILLARIES:
Microscopic vessels in the form of network connecting the
arterioles and the venules.
The heart between two lungs
Lung
Lung
Heart
Pericardium:
 It is a fibro serous sac that encloses the heart and roots of the great vessels.
Functions:
1.It provides lubricating container in which the heart can contracts easily.
2. It restrict excessive movement and over filling of the heart.
3.It protects and anchors the heart to the surrounding.
Location: It lies within the middle mediastinum, posterior to the body of the sternum.
Structure : It has a two layers fibrous and serous.
1-Fibrous pericardium:
 It is a conical sac, attached firmly below to the central tendon of the diaphragm, and
anteriorly to the sternum by the sternopericardial ligaments, it also fuse with the outer coat of
the great blood vessels namely the aorta, pulmonary trunk, superior and inferior vena cava,
and the pulmonary veins.
2-Serous pericardium:
It is a closed serous sac invaginated by the heart from above and behind.
It has two layers, with slit like space in-between ( pericardial cavity) which contains a small
amount of fluid ( pericardial fluid) which acts as lubricants.
It consists of two layers:
1. Parietal layer:
Lines the fibrous pericardium and reflected around the roots of the great vessels to become
continuous with them.
2. Visceral layer : (epicardium) closely applied to the heart.
The fibrous pericardium surrounding the heart:
2-THE HEART:
It is a hollow muscular organ lies within the pericardium in the middle
mediastinum, pyramidal in shape and it is connected at its base to the great blood
vessels.
Its base is directed upwards and to the right and its apex is directed downwards
and to the left.
It is about the size of closed fist with an average weight of 300 gm.
It is divided into 4 chambers 2 atria and 2 ventricles.
Function:
 It acts as double pump with two functions:
1. The right side receives deoxygenated blood and then pumps it to the lungs.
2. The left side receives the oxygenated blood from the lungs and pumps it to the
rest of the body.
Position of the heart:
The heart lies obliquely in the thorax, with its long axis passing downward and to
the left.
The right-sided chambers are mainly anterior to the left –sided due to heart
rotation during development.
The heart is a hollow muscular organ.
It consists of 4 chambers 2 atria and 2 ventricles.
1-Right atrium.
2-Left atrium.
3-Right ventricle.
4-Left ventricle.
Functions of the heart:
Summary:
The heart is a double pump, delivering
blood to the lungs for oxygenation, and then
to the body
Blood leaves the heart through arteries, and
returns to the heart through veins.
The heart rate is regulated by a conducting
system (the heart beats about 100,000 times
per day.
 Borders and apex of the heart:
 It has four borders and apex:
Borders:
1. Superior border :
It formed by the roots of great vessels .
2. Right border :
It formed by right atrium.
3.left border:
It formed by left auricle and left ventricle below.
4.Inferior border:
It formed by right ventricle (2/3) and the apical part of left ventricle
(1/3) .
Apex is formed by left ventricle (9cm from midline)..
 These borders are important when examining the heart radio
graphically.
Upper border of the heart is formed by the root of the great vessels.
Right border is
formed from
right atrium.
Left border is
formed by left
auricle and left
ventricle.
Lower border is formed by two ventricles mainly right.
Surfaces of the heart:
 It has four surfaces:
1.Sternocostal surface : it is formed mainly by right atrium, right ventricle(2/3), left
ventricle (1/3) which separated from each other by atrioventricular groove and
roots of great vessels.
2.Diaphragmatic surface ( inferior) :rested on the central tendon of diaphragm. it is
formed mainly by right ventricle (1/3) and left ventricles(2/3) separated by
posterior interventricular groove.
3.Right surface: it is formed by right atrium only. it related to right lung and pleura,
right phrenic nerve and pericardiaco-phernic artery.
4. left surface: It is formed by left ventricle and left atrium. It related to left lung
and pleura, left phrenic nerve and pericardiaco-phernic artery.
 The heart has apex and base:
 The apex of the heart:
 It is formed by the left ventricle only, it lies at the level of fifth left intercostal
space 9cm from the midline.
 The base (posterior surface):
 It consists of two atria mainly left atrium. It lies opposite the middle thoracic
vertebra (5,6,7,8).It separated from the vertebral column by structures in the
posterior mediastinum.
NB: The heart does not rest on its base ,it rests on its diaphragmatic surface.
Surfaces of the heart:
1.Sternocostal surface :
it is formed mainly by right
atrium, right ventricle(2/3), left
ventricle (1/3) which separated
from each other by atrioventricular
groove and roots of great vessels.
2.Diaphragmatic surface ( inferior) :
it rested on the central tendon of
diaphragm. it is formed mainly by
right ventricle (1/3) and left
ventricles(2/3)
separated
by
posterior interventricular groove.
3.Right surface:
 it is formed by right atrium
only.
4-left surface:
 It is formed by left ventricle
and left atrium.
The apex of the heart:
 It is formed by the left
ventricle only.
The
base
(posterior
surface):
 It consists of two atria
mainly left atrium.
The heart has sulci on the external
surfaces:
1-Coronary sulcus (atrio-ventricular):
 It separated between the 2 atria from
the 2 ventricles and lodges the 2
coronary arteries and coronary sinus.
2-Anterior
and
posterior
interventricular sulci.
 It separated the two ventricles
anterior and posteriorly and lodges
the corresponding interventricular
arteries.
Structures of the heart:
The heart wall is composed of a thick layer of cardiac muscle,
(myocardium), covered externally by(epicardium) visceral layer of
serous pericardium and internally by (endocardium).
All three layers are richly supplied with blood vessels.
It divided into 4 chambers by septum, the atrial portion has thin
walls and divided by interatrial septum into right and left atrium.
the ventricular portion divided by, interventricular septum .
 Chambers of the Heart:
The heart is divided by vertical septa into four chambers, the right
atrium which lies in front of left atrium, and right ventricle in front of
left ventricle .
The atria of the heart:
 Functionally, the atria are
receiving chambers for blood
returning to the heart from
the circulation (SVC and IVC).
 Because they need to
contract only minimally to
push
blood
into
the
ventricles, the atria are
relatively small, thin walled
chambers.
 As a rule they contribute
little to the propulsive
pumping of the heart.
Openings into the RA:
1.Superior vena cava :
It opens into upper part of RA, it
returns blood from upper half of the
body.
2.Inferior vena cava :
It opens into lower part of the RA, it
is guarded by a rudimentary non
functioning valve, it return blood
from lower half of the body.
3.Coronary sinus :
It drains most of the blood from the
heart, it opens into RA between the
IVC and right atrioventricular
opening .It has a valve.
4.The right
opening:
atrioventricular
 it lies anterior to the IVC opening.
5. Openings of many other small
veins.
 Valves of the heart: Valves control flow of blood from one chamber
to another and prevent backflow.
The heart has 4 valves.
1-Tricuspid valve:
It guards right atrioventricular orifice.
it is ovale in shape and admitting the tips of three fingers.
It consists of three cusps.
Its base are attached to the fibrous ring of the skeleton of the heart.
The cusps are :
A-Anterior : lies anterior.
B-Septal : lies against the Interventricular septum.
C-Inferior (posterior) :lies inferior .
2-Pulmonary valve:
 It guards the pulmonary orifice it is
circular orifice 3cm in diameter.
 it consists of three semilunar cusps
formed of endocardium and some
connective tissue.
The open mouths of the cusps are
directed upward
and the margin
and sides are attached to the arterial
wall.
The cusps are one posterior and two
anterior, during diastole blood flow
back enter the sinuses so the valve
cusps fill and come into apposition in
the centre of the lumen and close the
pulmonary orifice.
3-Mitral valve:
It is circular and admitted the tips of two fingers.
It is bicuspid (anterior and posterior) the cusps are attached to the
margin of the fibrous atrioventricular ring.
4-Aortic valve:
It is circular orifice 2.5 cm in
diameter.
It guard the aortic orifice and is
similar in structure to pulmonary
valve.
 It has three cusps one anterior
and two posterior (left and right
posterior) behind each one is aortic
sinus.
From the anterior sinus rise the
right coronary artery .
From the left posterior one rise
the left coronary artery.
Interventricular septum:
It lies obliquely between the 2 ventricles.
It is marked on the surface of the heart by the
anterior and posterior interventricular grooves.
It separates the Lt. ventricle from Rt. ventricle and
lower part of right atrium.
It is formed of two parts:
1- Muscular part.
2- Membranous part .
Nerve supply of the heart:
1-Parasympathetic nerve fibers arise as branches of the Vagus nerve in
the neck and thorax.
2-Sympathetic nerves travel to the heart from the cervical and upper
thoracic chain ganglia.
N.B: All nerves serving the heart pass through the cardiac plexuses on
the trachea before entering the heart.
Regulation of the cardiac cycle:
Sympathetic and parasympathetic
nervous
systems.
Parasympathetic: from medulla oblongata (vagus
nerve).Nerve branches to S-A and A-V nodes, and
secretes acetylcholine (slows rate).
Parasympathetic activity can increase (slow heart
rate) or decrease (increase heart rate).
Sympathetic nervous system through celiac
plexus to heart secretes norepinephrine increases
force of contractions.
Cardiac control center in medulla oblongata
maintains balance between the two.
Normally both sympathetic and parasympathetic
function at a steady background level.
Electrocardiogram (ECG) can trace conduction of
electrical signals through the heart:
 Blood supply of the heart:
The arterial supply of the heart is provided
by the right and left coronary arteries.
They and their branches are distributed over
the surfaces of the heart lying within
subepicardial connective tissue.
1.Right coronary artery:
It arises from the anterior ( right) aortic sinus
of ascending aorta , runs forward between
pulmonary trunk and the right auricle.
 It descends vertically in the right
atrioventricular groove, where it gives
branches to right atrium and right ventricle.
At the inferior border of the heart it
continues
posteriorly
along
the
interventricular groove to anastomosis with
left coronary artery.
2-The left coronary artery:
 It usually larger than the right
coronary artery.
 It arises from the left posterior
aortic sinus of the ascending aorta
and passes forward between the
pulmonary trunk and the left
auricle.
 It enters the atrioventricular groove
and divided into an anterior
interventricular
branch
and
circumflex branch.
Coronary artery disease results when
coronary arteries cannot deliver blood
adequately.
Usual cause: plaques in arterial walls.
Angina pectoris (pain) when body is
not receiving adequate oxygen.
Myocardial infarction (heart attack)
when blood supply to heart is
completely blocked; muscle dies.
Venous drainage of the Heart:
After passing through the myocardium, the venous blood is collected
by the cardiac veins.
Anterior cardiac veins : a series of small veins which runs
transversely to open into the right atrium.
Venae cordis minimi :are minutes veins which lies on the muscle wall
and drain directly into any chamber of the heart.
Coronary sinus: an enlarged vessel (3
cm in length) which lies in the
posterior part of the interventricular
groove as a continuation of the great
cardiac vein then empties into the
right atrium to the left of the IVC
opening.
Tributaries of coronary sinus:
1) Great cardiac vein: Ascends with
the
anterior
interventricular
artery, the curves with the
circumflex artery to end in the
coronary sinus.
2) Small cardiac vein :Accompany the
marginal artery.
3) Middle cardiac vein: Accompany
the posterior inter-ventricular
artery.
4) Posterior vein of left ventricle: To
the left of middle cardiac vein.
5) Oblique vein of left atrium (of
Marshal): Descends obliquely on
the back of the atrium.
Conduction system of the heart:
Heart contracts as a unit.
Atrial and ventricular syncytia help
conduct electrical signals through the
heart.
Sinoatrial (S-A) node is continuous
with atrial syncytium.
S-A node cells can initiate impulses on
their own; activity is rhythmic.
Coordination of chambers (contraction and relaxation):
Blood pressure:
Blood flow is generally equal to cardiac output.
Blood flow affected by pressure and resistance.
Blood pressure means the force that is exerted by blood against blood
vessel walls.
Resistance depends on size of blood vessel and thickness (viscosity) of
blood.
Baroreceptors detect changes in blood pressure.
Rising pressure  stretches receptors 
vagus
nerve
parasympathetic system  decrease heart rate decrease blood
pressure.
Increased temperature  increases heart rate.
Ions and heart rate:
 Excess potassium  decreases it .
 Excess calcium increases it.
 Blood pressure is highest in large arteries and
will rise and fall as heart pumps.
 highest with ventricular systole and lowest with
ventricular diastole.
 pulse pressure is the difference between
the
systole and diastole.
 Resistance is highest in capillaries.
 Control of blood pressure:
1. Regulation of cardiac output.
2. Contraction strength.
3. Heart rate.
4. Venous return.
5. Skeletal muscles.
6. Breathing rate.
Causes of increasing blood pressure:
(1)
(4)
(2)
(3)
(5)
 Hormonal regulation of blood flow .
If blood pressure is too low this leads to:
1-ADH (antidiuretic hormone) promotes water retention.
2-Angiotensin II- in response to renin signal (renin) produced
by kidney- why? Due to:
 Drop in blood pressure.
 Stimulation by sympathetic nervous system.
 Sodium levels too low.
Q:What happens?
1.
2.
3.
4.
Vasoconstriction (by angiotensin II).
ADH is secreted.
Aldosterone is secreted.
EPO (erythropoietin) secreted by kidneys.
If blood pressure is too high this leads to:
1- ANP(atrial natriuretic peptide) is secreted.
Q What is hypertension?
Is the arterial pressure is too high.
Causes:
Sometimes cause is unknown, or is secondary to
disease
Variety of causes/ risk factors are known.
Sedentary life style.
Smoking.
Obesity.
Diet (excess sodium; cholesterol; calories in
general).
Stress.
Arteriosclerosis.
Genetic factors.
Treatment of high blood pressure:
1. Quit smoking; adjust diet; exercise.
2. Drug therapies (strategies differ):
A-Reduce heart rate
Calcium channel blockers reduce calcium flow into heart
muscle and therefore reduce the heart rate and relax smooth
muscle lining coronary arteries.
Beta blockers (reduce stimulation by sympathetic nervous
system).
B-Diuretics reduce blood volume
ACE inhibitors interfere with renin-angiotensin pathway.
C-Vasodilators (such as nitroglycerin) open up blood
vessels (reduce resistance).
D-If heart is actually failing, digitalis increases efficiency
of heat muscle.
E-Anti-hypertensive
combination.
drugs
may
be
taken
in
Q Why the exercise is good for the
heart?
A trained heart is bigger and pumps
blood more efficiently (at a lower rate).
Stroke volume increases (due to
stronger contractions, allowing for lower
rate)
Other benefits: higher aerobic capacity
(contributing to efficiency)
Note that this takes training!
THANKS WITH THE BEST
WISHES.
Dr/Morsy Abd Elfattah.