Chapter 18: Anatomy of the
Cardiovascular System
Summary:
Anatomy of the Heart is:
4 chambers
4 valves
4 great vessels
3 layered covering
3 layered wall
3 circuits
The Heart is a muscular PUMP
(size and shape of a fist)
with 4 Chambers
Right Atrium Left Atrium
Right Ventricle Left Ventricle
The upper chambers ( R atrium, L atrium )
are for receiving Blood
The lower chambers (R Ventricle, L Ventricle)
are for pumping blood
•Located in the MEDIASTINUM
of the THORACIC CAVITY,
between the Right and Left Lungs,
posterior to the body of STERNUM,
Anterior to Thoracic Vertebrae 5-8.
Sits atop the diaphragm
 Right and Left Atria separated by the
membranous ATRIAL SEPTUM
RA
(valves separate RA/RV,
LA/LV)

LA
--- -- --- -- -- - --- --- ---
LV
Ventricles separated by the muscular
INTERVENTRICULAR SEPTUM
4 CARDIAC VALVES
 The Heart has 4 valves,
important in regulating the
filling
flowing
&
of the chambers
of the blood
TRICUSPID VALVE (Right Atrium / Right Ventricle)
MITRAL VALVE
(Left Atrium / Left Ventricle)
PULMONIC VALVE (right Ventricle / Pulmonary trunk {artery} )
AORTIC VALVE
(Left Ventricle / Aorta)
The Atrioventricular
valves
(tricuspid and mitral)
are composed of flat
flaps (cusps),
are connected
to the interior
ventricular walls via
Connective tissue
chords -- (CHORDAE
Tricuspid
TENDONAE),
valve
and
PAPILLARY MUSCLES.
The Pulmonic and the Aortic Valves are semilunar
valves,
Each with three billowy, pocket-like
leaflets
Chordae
tendonae
Pulmonic
valve
Aortic valve
Mitral
valve
Chordae
tendonae
Papillary
muscle
Auricles of Right and Left
Atria
 On both the Right & the Left Atrium,

there is an ear-like extension called the Auricle
these are visible on the external surface of the
heart:
Auricle of right atrium
Auricle of right atrium
Left ventricle
Apex of the heart
The HEART
VESSELS
and GREAT
 Each of the 4 cardiac chambers is associated with
Major Blood vessel/s:
(entering or exiting)
 Right Atrium : (in) Superior & Inferior Vena Cavae
 Right ventricle: Pulmonary Trunk (R & L pulm. arteries)
(out)
 Left Atrium:
Pulmonary veins
 Left Ventricle: Aorta
(out)
(in)
Superior Vena
Cava
Aorta
Pulmonary Trunk:
R & L Pulmonary arteries
Pulmonary veins
Inferior
Vena Cava
Note: red oxygenated, blue unoxygenated blood
(more on these to follow)
To remember great vessels: in order
VC, AA, PT, PV
vena cavae,
aortic arch,
Heart: posterior view
Triple layered Covering of
the heart: PERICARDIAL SAC
Heart coverings
protectthe
against
 Fibrous
Pericardium:
thick,friction
tough outer sac,
which is lined
By the
 Serous Pericardium: a thin, moist
double membrane,
the parietal layer,
which lines the fibrous
pericardium, and
the visceral layer, which adheres to & covers
the heart, it is also known as
THE EPICARDIUM
Coverings of the Heart
 Fibrous pericardium
 Serous pericardium (two-layered)


Parietal layer lines fibrous pericardium
Visceral layer (epicardium) forms outermost part of
heart wall

3 Layers of the heart
wall thin , moist - is the visceral
Epicardium:
pericardial membrane
 MYOCARDIUM - the Heart Muscle,
the left ventricular wall is three times as thick as
the right ventricle
 ENDOCARDIUM - the inner lining, made up of
single layer of ENDOTHELIUM,
( endothelium also lines the blood vessels of the
entire CVS)
Ventricles
( FYI )
 Two lower chambers known as pumping chambers
because, upon contraction, they push blood into
the large network of vessels
 Ventricular myocardium is thicker than the atrial
myocardium because great force must be
generated to pump the blood a large distance,
against systemic resistance. Myocardium of left
ventricle is thicker than the right for same reasons –
distance and increased resistance.
2
3
CIRCUITS
 A. PULMONARY CIRCUIT:
Right heart: unoxygenated blood from SVC & IVC
Right Atrium >>> Right Ventricle>>> Pulmonary Trunk
Right and left Pulmonary arteries, into the LUNGS,
for gases exchange; then to Heart via Pulm veins

B. SYSTEMIC CIRCUIT:
Left heart: oxygenated blood from PULM Veins
Left atrium >>> Left Ventricle >>> Aorta , and
the systemic arterial, capillary, venous network
C. CORONARY CIRCULATION: blood flow to the heart
***Flow of Blood Through Heart***
 Right side of heart is pulmonary circuit
pump
 Left side of heart is systemic circuit pump
right atrium (tricuspid valve) -> right ventricle
(pulmonary SL valve) -> lungs -> left atrium
(bicuspid (mitral) valve) -> left ventricle
(aortic SL valve) -> body tissues
Systemic & Pulmonary Circuits
Lung Bypasses in Fetal Heart


Foramen ovale – opening between right &left
atria; after birth closes to form fossa ovalis.
Ductus arteriosus – connection between
pulmonary trunk & aorta; closes to form
ligamentum arteriosum.
CORONARY ARTERIES:
BLOOD SUPPLY TO THE HEART
 THE FIRST BRANCHES off the AORTA,
immediately superior to the Aortic valve:
RIGHT CORONARY ARTERY,
LEFT MAINSTEM CORONARY ARTERY,
with its 2 quick branches: LEFT CIRCUMFLEX,
LEFT ANTERIOR DESCENDING.
Coronary blood flow actually occurs when the aortic
valve cusps are closed, during back-flow; not during
the powerful “systolic” pulsation of blood out of
the ventricle during contraction.
(systole)
(diastole)

CORONARY VEINS
Veins of the coronary circulation
 As a rule, veins follow a course that closely
parallels that of coronary
arteries.
After going through cardiac veins, blood enters
the CORONARY SINUS to drain into the right
atrium
 Several veins drain directly into the right atrium
posterior
anterior