Download heart

Dr.Sisara Bandara Gunaherath
MBBS
CVS consists of:
Heart
 Blood vessels

heartarteries arterioles


veinsvenules capillaries
What is the function of CVS

Circulate blood throughout entire body
for
◦
◦
◦
◦
Transport of oxygen to cells
Transport of CO2 away from cells
Transport of nutrients (glucose) to cells
Movement of immune system components
(cells, antibodies)
◦ Transport of endocrine gland secretions
Heart
The heart is a cone-shaped, muscular organ
 An adult human heart weighs between 200
and 425 grams (7 and 15 ounces) and is
slightly larger than a fist.
 The heart is located between the lungs in the
middle of the chest, behind and slightly to the
left of the sternum and in front of the spine

A double-layered membrane called the
pericardium surrounds the heart like a sac.
Layers of the heart wall
 Three layers of tissue form the heart wall. The
outer layer of the heart wall is the epicardium,
the middle layer is the myocardium, and the
inner layer is the endocardium.

Epicardium
The epicardium is the outer layer of the
wall of the heart. It is composed of
connective tissue ( mainly Adipose Tissue)
covered by epithelium.
 Coronary vessels and cardiac nerves
 The epicardium is also known as the
visceral pericardium
 Provides an outer protective layer for the
heart.

Cardiac Muscle/Myocardium
Intercalated Disc
Myocardium is the muscular middle layer
of the wall of the heart. It is composed of
spontaneously contracting cardiac muscle
fibers which allow the heart to contract.
 Stimulates heart contractions to pump
blood from the ventricles and relaxes the
heart to allow the artria to receive blood.

Endocardium
The endocardium is the inner layer of the
heart. It consists of epithelial tissue and
connective tissue.
 Lines the inner cavities of the heart,
covers heart valves and is continuous
with the inner lining of blood vessels.
 Purkinje fibers are located in the
endocardium. They participate in the
contraction of the heart muscle.
Pericardium
The pericardium is the fluid filled sac that surrounds the heart and
the proximal ends of the aorta, vena cava, and the pulmonary
artery.
 Pericardial Membranes
 The pericardium is divided into two layers:
Fibrous Pericardium - the outer fibrous sac that covers the
heart.
Serous Pericaridum – The membranous covering on the outside

The serous pericardium is divided in to

Parietal Pericardium

Visceral Pericardium
Functions of Pericardium

Keeps the heart contained in the chest
cavity.

Prevents the heart from over expanding
when blood volume increases.

Limits heart motion.
Chambers of the heart
The human heart has four chambers. The
upper chambers are called the left and
right atria, and the lower chambers are
called the left and right ventricles.
 A wall of muscle called the septum
separates the left and right atria and the
left and right ventricles.

The two atria are thin-walled chambers that
receive blood from the veins: the right atrium
receives deoxygenated blood from systemic
veins, while the left atrium receives
oxygenated blood from the pulmonary veins.
 The two ventricles are thick-walled chambers
that forcefully pump blood out of the heart.

Differences in thickness of the heart
chamber walls are due to variations in the
amount of myocardium present, which
reflects the amount of force each
chamber is required to generate.
 The left ventricle is the largest and
strongest chamber

Valves

Valves are flap-like structures that allow
blood to flow in one direction. The heart
has two kinds of valves, atrioventricular
and semilunar valves.
Atrioventricular Valves
The atrioventricular valves are thin
structures that are composed of
endocardium and connective tissue. They
are located between the atria and the
ventricles.
Mitral Valve
Tricuspid Valve

Semilunar Valves
The semilunar valves are flaps of
endocardium and connective tissue
reinforced by fibers which prevent the
valves from turning inside out.
 They are shaped like a half moon, hence
the name semilunar (semi-, -lunar).

The semilunar valves are located between
the aorta and the left ventricle and
between the pulmonary artery and the
right ventricle.
Aortic Valve
Pulmonary Valve

Function of the Heart
Right Side of the Heart

The right side of the heart receives deoxygenated blood from the body tissues
(from the upper- and lower-body via the
Superior Vena Cava and the Inferior Vena
Cava, respectively) into the right atrium.
This de-oxygenated blood passes through
the tricuspid valve into the right ventricle.
 This blood is then pumped under higher
pressure from the right ventricle to the
lungs via the pulmonary artery

Left-Hand Side of the Heart
The left-hand side of the heart receives
oxygenated blood from the lungs (via the
pulmonary veins) into the left atrium.
 This oxygenated blood then passes through
the bicuspid valve into the left ventricle.

It is then pumped to the aorta under greater
pressure
 This higher pressure ensures that the
oxygenated blood leaving the heart via the
aorta is effectively delivered to other parts of
the body via the vascular system of blood
vessels (incl. arteries, arterioles, and
capillaries).
