Anatomy Practical
[PHL 212]
Cardiovascular System
The Cardiovascular System
 A closed system of the heart and blood vessels
• The heart pumps blood
• Blood vessels allow blood to circulate to all parts of
the body
a. Pulmonary circuit—flow of blood through the lungs.
 Pulmonary arteries—carry O2-poor blood from right ventricle to
the lungs.
 Pulmonary veins—carry O2-rich blood from lungs to the left
atrium.
b. Systemic circuit—flow of blood through the rest of the body.
 Aorta—carries O2-rich blood to all body tissues.
 Vena cava—returns O2-poor blood to the right atrium.
 The function of the cardiovascular system is to deliver
oxygen and nutrients and to remove carbon dioxide and
other waste products
The Heart: Size & Location
 The heart is a hollow, cone-shaped, muscular pump
 Nine (9) inches long x three (3) inches wide.
 Located in the centre of Thorax between the lungs
posteriorly by the backbone, and anteriorly by the
sternum & resting upon the diaphragm.
 Base--attached to several large blood vessels and
lies beneath the second rib.
 Pointed apex at the fifth intercostal space directed
toward left
Location of Heart in thorax
The Heart: Coverings
 The heart and the proximal ends of the large blood
vessels are enclosed by the pericardium.
 Consists of an outer fibrous pericardium which
surrounds a more delicate double-layered sac.
 Inner layer of this sac--visceral pericardium
(epicardium) covers the heart.
 At the base of the heart the visceral pericardium
turns back on itself to become the parietal
pericardium.
 Between the parietal and visceral layers is the
pericardial cavity which contains serous fluid-pericardial fluid.
The Heart: Heart Wall
 Three layers
 Epicardium (Outer layer)
 consists of connective tissue covered by epithelium
 Functions as an outer protective layer
 Myocardium (Middle layer)
 Relatively thick
 Consists largely of cardiac muscle tissue responsible for forcing blood
out of the heart chambers
 Pumps 70 ml blood with each contraction
 Endocardium (Inner layer)
 Relatively thin sheet consists of epithelial and connective tissue that
contains many elastic and collagenous fibers.
 Lines all of the heart chambers and covers heart valves
Heart Wall
The Heart: Associated Great Vessels
 Aorta
 Leaves left ventricle
 Pulmonary arteries
 Leave right ventricle
 Vena cava
 Enters right atrium
 Pulmonary veins
 Enter left atrium
External Heart Anatomy
The Heart: Chambers
 Four chambers
 The Atrium
Upper two chambers
Divided into the Left Atria and the Right Atria
Brings in Blood from the Veins
Receiving chambers
 Ventricles
Lower two chambers
Divided into Left Ventricle and Right Ventricle
Pumps in Blood into the arteries
Discharging chambers
The Heart: Valves
 Allow blood to flow only in one direction
 Four valves
 Atrioventricular valves – between atria and
ventricles
 Bicuspid or Mitral valve (left)
 Tricuspid valve (right)
 Semilunar valves between ventricle and artery
 Pulmonary semilunar valve
 Aortic semilunar valve
Right Heart Chambers
• Right Atrium
– Receives O2-poor blood from body via Superior and Inferior vena cava
• Right Ventricle
– Receives O2-poor blood from right atrium through tricuspid valve
– Pumps blood to lungs via Pulmonary Semilunar Valve in pulmonary
trunk
Left Heart Chambers
• Left Atrium
– Receives O2-rich blood from lungs via 4 Pulmonary Veins
• Left Ventricle (forms apex of heart)
– Receives blood from Left Atrium via bicuspid valve (Mitral valve )
– Pumps blood into aorta via Aortic Semilunar Valve to body
Heart Chambers and Valves
Blood Circulation
Two circulatory paths
Systemic
Pulmonary
Walls of Arteries and Veins
• Tunica externa
– Outermost layer
– Connective tissue with varying
quantities of elastic fibers and
collagen fibers
• Tunica media
– Middle layer
– Circular Smooth Muscle
– Vaso-constriction/dilation
• Tunica intima
– Innermost layer
– Simple squamous epithelium
(endothelium).
– Minimize friction
• Lumen
Differences Between Artery & Vein
Arteries
Veins
Direction of flow Blood Away from Heart Blood to Heart
THICKER: Tunica
THINNER: Tunica
Walls
media thicker than tunica externa thicker
externa
than tunica media
Lumen
Pressure
Valves
Smaller
Larger
Higher
Lower
No valves
Valves
1. Blood transported by the pulmonary veins returns to the
left atrium.
right atrium.
right ventricle.
left ventricle.
2. The valve between the left ventricle and the blood vessel leaving the left
ventricle is the
bicuspid valve.
tricuspid valve.
pulmonary semilunar valve.
aortic semilunar valve.
3. The valve located between the right atrium and the right ventricle is the
tricuspid valve.
bicuspid valve.
mitral valve.
semilunar valve.