Bell ringer
• Why does our heart need to have fluid
surrounding it?
Cardiovascular System:
The Human Heart
EQ
• What are the different structures of the heart
that allow it to pump blood throughout our
bodies?
• FOCUS: external layers of the heart and heart
wall.
The Human Heart
• Located between the
lungs in thoracic cavity
• Pointed end called apex
• Acts as a pump to
propel blood through
the body
Layers of the heart
• Outer Membrane
–Pericardium
• Heart Wall ( from outside to inside)
–Epicardium
–Myocardium
–Endocardium
Pericardium
• Membrane that surrounds and protects the
heart
• Made of two layers:
– Fibrous Pericardium
– Serous Pericardium
Fibrous Pericardium (Outer)
• Outer layer of the
pericardium
• Tough, dense, inelastic
connective tissue
• Prevents stretching of
the heart
• Provides protection
• Anchors heart in place
Serous Pericardium (Inner)
• Thin membrane
• Forms a double layer
around the heart
– Parietal Layer (outer layer)
– Visceral Layer (inner layer)
• Same as epicardium
• Pericardial Cavity
– Between parietal and
visceral layer
– Contains pericardial fluid ->
reduces friction between
membranes as heart
moves
Heart Wall
• Epicardium
– also visceral layer of serous
pericardium
– Thin transparent outer
layer of the heart wall
• Myocardium
– Consists of cardiac muscle
tissue -> only found in the
heart
– Makes up the bulk of the
heart
– Responsible for pumping
action of the heart
Heart Wall
• Endocardium
– Thin epithelial layer that
lines the inside of the
heart
– Covers the valves and
tendons inside the heart
– Continuous with
epithelial lining of large
blood vessels
Parts of the Heart
The Heart: Chambers
• Right and left side act as separate pumps
• Four chambers
– Atria
• Receiving chambers
– Right atrium
– Left atrium
– Ventricles
• Discharging chambers
– Right ventricle
– Left ventricle
Figure 11.2c
Blood Circulation
Figure 11.3
The Heart: Valves
• Allow blood to flow in only one direction
• Four valves
– Atrioventricular valves – between atria and
ventricles
• Bicuspid valve (left)
• Tricuspid valve (right)
– Semilunar valves between ventricle and artery
• Pulmonary semilunar valve
• Aortic semilunar valve
The Heart: Valves
• Valves open as blood is pumped through
• Held in place by chordae tendineae (“heart
strings”)
• Close to prevent backflow
The Heart: Associated Great Vessels
• Aorta
– Leaves left ventricle
• Pulmonary arteries
– Leave right ventricle
• Vena cava
– Enters right atrium
• Pulmonary veins (four)
– Enter left atrium