The heart is located in the middle mediastinum of the chest. It has four chambers - right atrium, right ventricle, left atrium and left ventricle. The heart has four valves that separate its chambers and allow blood to flow in one direction. It is surrounded by membranes called pericardium. The heart develops from the cardiogenic area in the embryo and forms as a primitive heart tube that undergoes looping and partitioning into chambers.

1. ANATOMY OF
HEART

2. LOCATION
Placed in the middle of the
chest or thoracic cavity
( middle mediastinum),
posterior to the body of
sternum and the second to
sixth costal cartilages and
anterior to the fifth to the
eighth thoracic vertebrae.
The heart rests on the
superior surface of the
diaphragm.

3. SHAPE and size
• Roughly cone shaped hallow
muscular organ.
• 12 (5in.) long, 9 cm(3.5 in.)wide
and 6cm(2.5 in.) thick.
• Weight – 250g in adult females
and 300 g in adult males.

4. CHAMBERS
• Four Chambers:-
Right atrium
Right ventricle
Left atrium
Left ventricle

5. CHAMBERS
• Right atrium:- It is about 2-3 mm (0.08-0.12 in.) in
average thickness. The right atrium forms the
right border of the heart and receives blood from
three veins: the superior vena cava, inferior vena
cava and coronary sinus.
• Right ventricle:- The right ventricle is about 4-5
mm (0.16-0.2 in.) in average thickness and forms
most of the anterior surface of the heart and
receive blood from the right atrium and pumps it
into the pulmonary artery.

6. CHAMBERS
• Left atrium:- The left atrium is about the same
thickness as the right atrium and forms most of
the base of the heart. It receives oxygenated
blood from the pulmonary veins and pumps it
into the left ventricle.
• Left ventricle:- the thickest chamber of the heart,
averaging 10- 15mm (0.4-0.6 in.) and forms the
apex of the heart. It receives oxygenated blood
from the left atrium and pumps it into the aorta.

7. VALVES of the heart

8. VALVES OF THE HEART
• The heart has four valves, which separate its chambers. One
valve lies between each atrium and ventricle
• The valves between the atria and ventricles are called the
atrioventricular valves.
• Between the right atrium and the right ventricle is
the tricuspid valve. The tricuspid valve has three cusps.
• The mitral valve lies between the left atrium and left ventricle.
It is also known as the bicuspid valve due to its having two
cusps, an anterior and a posterior cusps.

9. VALVES OF THE HEART
• The aortic and pulmonary valves are known as
the semilunar valves.( semi= half, lunar= moon
shaped) because they are made up of three
crescent moon shaped cusps.

10. VALVES OF THE HEART
• The pulmonary valve is located at the base of the pulmonary
artery. This has three cusps which are not attached to any
papillary muscles. When the ventricle relaxes blood flows
back into the ventricle from the artery and this flow of blood
fills the pocket-like valve, pressing against the cusps which
close to seal the valve.
• The semilunar aortic valve is at the base of the aorta and also
is not attached to papillary muscles. This too has three cusps
which close with the pressure of the blood flowing back from
the aorta.

11. LAYERS OF THE HEART

12. LAYERS OF THE HEART
• Consists of three layers:-
 Epicardium( external layer)
 Myocardium(middle layer)
 Endocardium (inner layer)
 EPICARDIUM:- The thin , transparent outer layer of the heart wall,
also called the visceral layer of the serous pericardium. Is
composed of delicate connective tissue.
 MYOCARDIUM:- (MYO= muscle) which is cardiac muscle tissue,
makes up about 95% of the heart and is responsible for its pumping
action.
 ENDOCARDIUM:- (ENDO=within) is a thin layer of endothelium. It
provides smooth lining for the chambers of the heart and covers
the valves of the heart.

13. LAYERS OF THE HEART
• PERICARDIUM:- The membrane that surrounds and
protects the heart is the pericardium.
• The pericardium consists of two main parts:-
Fibrous pericardium (superficial):- Is composed of tough,
inelastic, dense irregular connective tissue. It resembles a
bag that rests on and attaches to the diaphragm.
Serous pericardium( deeper):- Thin, more delicate
membrane that forms a double layer around the heart.
The outer parietal layer of the serous pericardium is
fused to the fibrous pericardium. The inner visceral layer
of the serous pericardium also called the epicardium. The
space that contains the few millimeters of pericardial
fluid is called the pericardial cavity.

14. CONDUCTION SYSTEM

15. • SA Node (located in the right atrial wall just inferior
and lateral to the opening of the superior vena
cava).
• AV Node( located in the interatrial septum, just
anterior to the opening of the coronary sinus.
• AV Bundle(located at the inferior end of the
interatrial septum to the ventricles of the heart)
• Purkinje Fibre( Located in the inner ventricular walls
of the heart, just beneath the Endocardium in a
space called the subendocardium).

16. CARDIAC CYCLE
• It depends upon 3 mechanisms:-
Atrial systole
Ventricular systole
Relaxation period

17. CARDIAC CYCLE

18. SYSTEMIC AND PULMONARY
CIRCULATION

20. CARDIAC OUTPUT
• It is the volume of blood ejected from the left
ventricle or the right ventricle into the aorta or
pulmonary trunk each minute.
• Cardiac output is the equals the stroke volume
(SV) , the volume of blood ejected by the
ventricle during each contraction, multiplied
by the heart rate (HR), the number of
heartbeats per minute:-

21. CARDIAC OUTPUT
CO = SV X HR
(mL/MIN) (mL/beat) (beats/min)
Stroke volume average 70 ML/beat, and heart
rate is about 75 beats/min. Thus, average
cardiac output is
CO= 70mL/beat x 75 beats
=5250 mL/min =5.25 L/min

22. HEART SOUNDS
• In a healthy heart, there are only two audible heart
sounds, called S1 and S2. The first heart sound S1, is
the sound created by the closing of the
atrioventricular valves during ventricular contraction
and is normally described as "lub". The second heart
sound, S2, is the sound of the semilunar valves
closing during ventricular diastole and is described as
"dub"

23. HEART SOUNDS
• Additional heart sounds may also be present and
these give rise to gallop rhythms. A third heart sound,
S3 usually indicates an increase in ventricular blood
volume. A fourth heart sound S4 is referred to as an
atrial gallop and is produced by the sound of blood
being forced into a stiff ventricle. The combined
presence of S3 and S4 give a quadruple gallop.

24. BLOOD VESSELS

25. • The three structural layers of a blood vessel
TUNICA INTERNA:- It forms the inner lining of a blood
vessel and is in direct contact with the blood as it
flows through the lumen.(squamous epithelium
called endothelium).
TUNICA MEDIA:- It is a middle layer. Muscular and
connective tissue layer.
TUNICA EXTERNA:- The outer covering of a blood
vessel, consists of elastic and collagen fibers.

26. EMBRYOLOGY OF HEART

27. EMBRYOLOGY OF HEART
The cardiovascular system is one of the first systems to form in
an embryo and the heart is the first functional organ.
19 DAYS( Location of cardiogenic area):- The heart begins its
development from mesoderm on day 18 or 19 following
fertilization. In the head end of the embryo the heart
develops from a group of the mesodermal cells called the
Cardiogenic area.( cardio= heart, genic= producing)
20 DAYS(FORMATION OF ENDOCARDIAL TUBES):- In response to signals
from the underlying endoderm, the mesoderm in the
Cardiogenic area forms a pair of elongated strands called
Cardiogenic cords. Shortly after these cords develop a hollow
center and then become known as endocardial tubes.

28. EMBRYOLOGY OF HEART
• 21 DAYS( FORMATION OF PRIMITIVE HEART TUBE):- With lateral
folding of the embryo, the paired endocardial tubes
approach each other and fuse into a single tube called
the primitive heart tube.
• 22 DAYS (DEVELOPMENT OF REGIONS IN THE PRIMITIVE HEART
TUBE):- The primitive heart tube develops into five
distinct regions and begins to pump blood. From tail
end to head end they are the:-
 Sinus venosus(develops into part of the right atrium,
coronary sinus, and sinoatrial (SA) node.
 Atrium (develops into part of the right atrium, right
auricle and the left atrium and left auricle.
 Ventricle ( gives rise to the left ventricle)
 Bulbus cordis ( develops into the right ventricle)
 Truncus arteriosus ( gives rise to the ascending aorta
and pulmonary trunk)

29. • 23 DAY(BENDING OF THE PRIMITIVE HEART):- The primitive
heart tubes elongates a. Because the bulbus cordis
and ventricle grow more rapidly than other parts of
the tube and the tube begins to loop and fold. At
first, the primitive heart tube assumes a U shaped;
later it becomes S shaped.
• 28-35 DAYS (ORIENTATION OF ATRIA AND VENTRICLES TO THEIR
FINAL ADULT POISITION):- The atria and ventricles of the
future heart are reoriented to assume their final
adult positions.