Cardiovascular System
The Heart
Location & Size
Size of a fist; less than a pound
 Apex – points to left hip
 Base – points towards right shoulder

Pericardium

Visceral pericardium (epicardium)
– hugs external surface of heart
– part of the heart wall

Parietal pericardium
– anchors the heart to surrounding structures
such as the diaphragm and sternum.
Layers of Heart Wall

Epicardium (visceral pericardium)
– Outer layer

Myocardium
– Layer that contracts
– Thick bundles of cardiac muscle

Endocardium
– Thin sheet of endothelium
– Lines the heart chambers
Chambers

Atria (2)
– Receiving chambers

Ventricles (2)
– Discharging chambers
Interventricular or interatrial septum –
divides the heart longitudinally
http://www.starsandseas.com/SAS_Images/SAS_Physiol_Images/SAS%20cardiopics/heart_chambers.jpg
Blood Vessels

Superior & inferior venae cavae
– Receives deoxygenated blood from veins of
the body

Pulmonary trunk
– Receives deoxygenated blood pumped out
from the right ventricle
Blood Vessels

Right and left pulmonary arteries
– Branches off from pulmonary trunk

Pulmonary veins (4)
– Receives oxygenated blood from the lungs

Aorta
– Receives oxygenated blood pumped out from
the left ventricle
Valves
Atrioventricular valves (AV valves)
 Chordae tendineae
 Semilunar valves

Atrioventricular valves (AV valves)
Located between atrium and ventricle
 Prevents backflow into the atria when
ventricles contract
 Bicuspid valve

– Left AV valve
– Consists of two cusps or flaps

Tricuspid valve
– Right AV valve
– Has three cusps
Chordae tendineae

Tiny white
cords that
anchor the
cusps to the
walls of the
ventricles.
Semilunar valves

Each valve has three cusps
– cusps forced open as ventricles contract
– Blood flows back after contraction closing
cusps.

Pulmonary semilunar valve
– Between right ventricle and pulmonary trunk

Aortic semilunar valve
– Between left ventricle and aorta