2. Lies within the
pericardium in middle
mediastinum.
Behind the body of
sternum and from 2nd to
5th inter-costal spaces.
A third of it lies to the
right of median plane and
2/3 to the left.
3. A hollow muscular organ,
pyramidal in shape,
Consists of four chambers( right
and left atria, right and left
ventricles).
Cardiac Apex is formed by left
ventricle and is directed
downwards and forwards to the
left.
It lies at the level of the 5th left
intercostal space.
EXTERNAL CHARACTERISTIC
4. ►Approximately the size of your fist.
►Wt.= 250-300 grams
►Cardiac base is formed by the left
atrium and to a small extent by the
right atrium. It faces backward,
upward and to the right.
6. FOUR GROOVES
■ Coronary sulcus which
marks the
the division between atria and
ventricles
■ Interatrial groove separates
the two atria
■ Interventricular groove-
anterior and posterior, marks
the division between ventricles
7. ●Pericardium- a double walled
sac around the heart.
Composed of:
A superficial fibrous
pericardium
A deep two-layer serous
pericardium
Interatrial septum
Located between right and left atria.
Contains fossa ovalis
Interventricular septum
Located between right and left atria
9. Atria- receiving chambers of
the heart.
■Receive venous blood
returning to heart.
■Separated by an interatrial
septum.
■Blood enters right atria from
superior and inferior vena cava
and coronary sinus.
■Blood enters left atria from
pulmonary veins.
10. VENTRICLE OF THE HEART
Ventricles- are the discharging
chambers of the heart.
■Separated by an interventricular
septum
Contains components of the conduction
system.
■Right ventricle pumps blood into
the pulmonary trunk.
■Left ventricle pumps blood into
the aorta.
11. Two major types:
■Atrioventricular valves
■Semilunar valves
Atrioventricular(AV) valves lie
between the atria and the
ventricles
R-AV VALVE = Tricuspid valve
L-AV VALVE= Bicuspid or mitral
valve
12. ■Semilunar valves prevent backflow of
blood into the ventricles.
■Aortic semilunar valve lies between the
Ventricles and pulmonary trunk.
■Pulmonary semilunar valve lies between
the right ventricle and pulmonary trunk.
■Heart sounds (“lub-dub”) due to valves
Closing
“Lub”- closing of atrioventricular valve
“Dub”- closing of semilunar valves
13. The heart is supplied by sympathetic and
parasympathetic fibers via the cardiac plexus
situated below the arch of aorta.
The beating of the heart is regulated by the
Intrinsic conduction (Nodal) system.
1. Sinoatrial(SA)node[Pacemaker] located in
the right atrium it generates the impulse.
2. Atrioventricular(AV)node is located at the
junction of the atria and the ventricles
3. Atrioventricular(AV)bundle(bundle of his)
is located in the interventricular septum.
14. The arterial supply of the heart
is provided by the right and left
coronary arteries
Drains into the right atrium
through coronary sinus.
It is continuation of great cardiac
vein
15. Clinical correlation of various
anatomical structures
1.Congenital Atrial Septal Defects
Failure of fusion of septum primum and septum
secundum leads to a patent foramen ovale after birth.
2. Endocarditis
Inflammation of endocardium is referred to endocarditis
and that of myocardium as myocarditis.
3. Mitral stenosis
Due to infection and subsequent fibrosis , the cusps
become thick with reduced mobility often fuse with each
other.
16. 4.Pericarditis
Inflammation of pericardium
5.Pericardial effusion
The pericardial cavity may be filled by fluid
6.Aortic aneurysms
A dilatation of a segment of aorta is called as aneurysm
7.Myocardial infarction
Complete blockage of a branch of a coronary artery
leads to death of a part of myocardium supplied by that
branch.
8.Atherosclerosis
Building up of fats, cholesterol and other substances in
and on artery walls.
17. The heartbeat originates in a specialized cardiac
conduction system.
The heart beats normally in an orderly sequence:
Contraction of atria (atrial systole) is followed by
contraction of the ventricles (ventricular systole)
and during diastole all four chambers are
relaxed.
18. Action potentials (electrical
impulses) in the heart originate in
specialized cardiac muscle cells,
called autorhythmic cells.
These cells are self-excitable, able to
generate an action potential without
external stimulation by nerve cells.
The autorhythmic cells serve as a
pacemaker to initiate the cardiac
cycle and provide a conducting
system to coordinate the contraction
of muscle cells throughout the heart.
19. The autorhythmic cells are concentrated in
the structures that make up the conduction
system
The sinoatrial node (SA node)
The internodal atrial pathways
The atrioventricular node (AV node)
The bundle of His and its branches
The purkinje system.
20. Sino atrial node
It is a part of the wall of
right atrium close to the
opening of superior
venacava.
It generates impulses
approximately at the rate of
72 times/min.
Atrio ventricular node
It is a part of the wall of
right atrium close to the
atrioventricular septum
and near to the tricuspid
valve.
It generates impulses
approximately at the rate
of 60 times/min.
21. Bundle of His
It is a thick band of
muscle fibers starting
from AV node.
It generates impulses
approximately at the
rate of 40 times/min.
Purkinje Fibers
These fibers arise from
the branches of bundle
of His.
This fibers pierce into
the ventricular
myocardium.
