Download The Right Coronary Artery

PHYSIOLOGY OF THE
CARDIOVASCULAR SYSTEM
The Heart
Introduction
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Cardiovascular system is comprised of the Heart
and Blood vessels
Heart is the central pump and the blood vessels are
series of distributing and collecting tubes.
CVS forms one of the major coordinating system of
the human body
The Heart – Anatomy and Physiology
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The heart is located in the thoracic cavity between
the lungs. This area is called the mediastinum.
The base of the cone-shaped heart is uppermost,
behind the sternum, and the great vessels enter or
leave here.
The apex (tip) of the heart points downward and is
just above the diaphragm to the left of the midline.
Chambers
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It is divided into four chambers: a right and a left
atrium both lying superiorly, and a right and left
ventricle both lying inferiorly and larger.
The atria are separated by a thin interatrial
partition called interatrial septum, while the
ventricles are separated by thick muscular partition
called interventricular septum.
The thickness of the right ventricular wall is 0.30.5cm and while that of the left ventricular wall is
1.3-1.5 cm
Movement of the Blood
Valves
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The transport of blood is regulated by cardiac
valves: two loose flap-like atrioventricular valves,
tricuspid on the right and mitral (bicuspid) on the
left.
Two semilunar valves with three leaflets each, the
pulmonary and aortic valves guards the outflow
tract.
The Normal Circumference of the valvular openings;
Tricuspid-12cm, Pulmonary SLV-8.5cm, Aortic SLV7.5cm and Mitral Valve -10cm
Layers of the Heart
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The wall of the heart consists mainly of the
myocardium which is covered externally by thin
membrane, the epicardium or visceral pericardium,
and lined internally by another thin layer, the
endocardium.
Myocardium
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Muscle tissue of the heart
Composed of syncytium of branching and
anatomizing, transversely striated muscle fibers
arranged in parallel fashion.
Contains a rich capillary network and loose
connective tissue.
Myocardial fibers are connected to each other by
intercalated discs.
Myocardium
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They form tight junctions for free transport of ions and
action potential.
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Cardiac myocytes are rich in Mitochondria.
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It also contains more sarcoplasmic reticulum
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The conduction system of the heart in the myocardium is
responsible for regulating rate and rhythm of the heart.
Pericardium
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The heart is enclosed in the pericardial
membranes, of which there are three layers:
The outermost is the fibrous pericardium, a loose
fitting sac of strong fibrous connective tissue that
extends inferiorly over the diaphragm and
superiorly over the bases of the large vessels that
enter and leave the heart.
Pericardium
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The serous pericardium is a folded membrane; the
fold gives it two layers, parietal and visceral. Lining
the fibrous pericardium is the parietal pericardium.
On the surface of the heart muscle is the visceral
pericardium, often called the epicardium.
Between the parietal and visceral pericardial
membranes is serous fluid, which prevents friction
as the heart beats.
Endocardium
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Smooth shiny inner lining of the myocardium
Covers all cardiac chambers, cardiac valves, the
chordae tendineae and the papillary muscles.
It is lined by endothelium with connective tissue and
elastic fibres in its deeper part.
The valve cusps and semilunar leaflets are delicate
and translucent structures.
The valves are strengthened by collage and elastic
tissue and covered by a layer of endothelium
(valvular).
Blood Supply
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Blood is transported to the myocardium by
Coronary arteries.
Most of the blood supply occurs during diastole.
There are three major coronary trunks
The Anterior Descending Branch of the Left
Coronary Artery
The Circumflex Branch of the Left Coronary Artery
The Right Coronary Artery
Blood Supply
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The Anterior Descending Branch of the Left
Coronary Artery
 Supplies
most of the apex of the heart
 Anterior surface of the left ventricle
 Adjacent third of the anterior wall of the right ventricle
 Anterior two third of the interventricular septum
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The Circumflex Branch of the Left Coronary
Artery
 Supplies
left atrium
 Small portion of the lateral aspect of the left ventricle
Blood Supply
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The Right Coronary Artery
 Supplies
Right Atrium
 Anterior surface of the right ventricle
 The adjacent half of the posterior wall of the left
ventricle and
 The posterior third of the interventricular septum
Anatomic Patterns of Blood Supply
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Three anatomic patterns of distribution of the blood
supply, depending upon the blood vessel that
crosses the Crux.
Crux is the region on the posterior surface of the
heart where all the four chambers and interatrial and
interventricular septa meet.
Anatomic Patterns of Blood Supply
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Balanced Coronary Artery Distribution
 Right
and Left ventricles receives blood from Right and
Left Coronary artery.
 Posterior part of the interventricular septum is supplied
by branch of right coronary artery
 Anterior part is supplied by the branch of Left
Coronary artery
Anatomic Patterns of Blood Supply
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Left Coronary Artery Preponderance
 Entire
left ventricle receives blood from LCA, whole of
interventricular septum and
 Posterior wall of the Right ventricle
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Right Coronary Artery Preponderance
 Entire
Right ventricle
 Posterior half of the interventricular septum
 Posterior wall of the left ventricle by crossing the Crux.
A. Balanced Coronary Circulation
B. LCA Preponderance
C. RCA Preponderance