Cardiovascular System
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Review of The Heart
Cardiovascular System
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For the purpose of this course, interest in
cardiovascular system are limited to :
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Blood circulation system
Cardiac cycle
Cardiac output
Cardiac work
We’ll try to relate the cardiac function of the
heart with the operation of heart assist device
particularly VAD.
Cardiovascular System
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Anatomy of The Heart
Cardiovascular System
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Heart is a muscular organ in human body where the main function is
to pumps blood to all over the body.
Located in the chest between the lungs behind the sternum and
above the diaphragm.
Heart walls composed of three layer of muscles : epicardium,
myocardium and endocardium.
Myocardium is the thickest muscle among them. It is the one that
contracts and thus responsible for pumping action of the heart.
The heart also has four chambers consists of two atria and two
ventricles.
Blood flow into atria and then fill the ventricles. Then blood will be
pumped out from the heart when ventricles wall contracts.
Atria acts like a reservoir which receives blood that returns to the
heart while ventricles acts as a pump which ejects blood out to the
body.
Cardiovascular System
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Layers of Heart Muscle
Cardiovascular System
Valves
 There are four valves in the heart which will ensure only one-way
flow of blood through heart chambers.
 All these valves can be categorized into two types i.e.
atrioventricular valves and semilunar valves.
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Atrioventricular (AV) valves located between atrial and ventricular
chambers. It prevents backflow to atria when ventricles contract.
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AV consists of mitral valve (also known as biscupid valve) at left
side of the heart and tricuspid valve on the other side
 Semilunar valves consists of pulmonary valve and aortic valve.
 These valves guards the bases of the two large arteries leaving the
ventricular chambers.
Cardiovascular System
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Blood Circulatory System
Cardiovascular System
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Human blood circulatory system can be divided into two parts i.e.
pulmonary circulation and systemic circulation.
Oxygenated blood is oxygen rich, CO2 poor blood indicated by red color.
Deoxygenated blood CO2 rich, oxygen poor blood indicated by blue color.
Pulmonary Circulation
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Circulation of blood from heart to lungs and back to heart.
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Deoxygenated blood flow out of heart through pulmonary artery to the
lungs.
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At lungs, oxygen is picked up and CO2 unloaded.
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Oxygenated blood then goes back to heart via pulmonary vein.
Systemic Circulation
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Blood circulates from heart to all other parts of body except lung.
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Oxygenated blood leaves heart through aorta to the body.
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Oxygen in blood diffuses into cells and CO2 diffuses from cells into blood.
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Deoxygenated blood then goes back to the heart through vena cava.
Cardiovascular System
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Physiology of The Heart
Blood Flow in The Heart
 Deoxygenated blood from the body returns to the heart via vena
cava and enters the right atrium.
 Then, the blood will fill the left ventricle before the ventricles contract
ejecting the blood to the lungs through pulmonary artery.
 Oxygenated blood from the lungs goes into the heart via pulmonary
vein and enters the left atrium.
 The blood then passes into left ventricle and ejected into the aorta.
Mechanism of Pumping
 Blood returning to heart will enter the atria
 The blood put pressure against the AV valves which forces the
valves to open.
 Blood will fills the ventricles. Contraction of atria will force additional
blood into ventricles.
 Then, when ventricles contracts, blood will forces the AV valve to
close.
Cardiovascular System
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At the same time, blood will put pressure against semilunar valves
forcing them to open.
As ventricles relax, blood flows back from arteries, filling the leaflets
of semilunar valves and forcing them to close.
Notes:
 ‘Blood Flow in The Heart’ describes the path which blood go through
in the heart.
 ‘Mechanism of Pumping’ describes what happens in the heart during
one cardiac cycle.