 Three essential components of the circulatory system are:
1. Heart – a pump to push blood through the system
2. Blood vessels – a connecting series of tubes through
which blood travels
3. Blood – a transport medium used to move materials
throughout the system.
 The human heart is an organ that pumps blood
throughout the body via the circulatory system,
supplying oxygen and nutrients to the tissues and
removing carbon dioxide and other wastes.
 The function of the heart is to maintain a
constant circulation of blood around the
body by its pumping action.
 The walls of the heart consist of cardiac muscle,
which never tires.
 Heart muscles are myogenic
 Four (4) chambers
 Right Atrium
 Left Atrium
 Right Ventricle
 Left Ventricle
 Superior and Inferior vena cava > right atrium > tricuspid
valve > right ventricle > pulmonary valve > pulmonary
arteries > lungs > pulmonary veins > left atrium > bicuspid
valve > left ventricle > aortic valve > aorta > body (except
lungs).
A group of special muscle cells that sends
electrical signals to the heart from the brain to
speed up or slow down.
 There are two (2) types of systole:
1. Atrial systole – Atria contracts, tricuspid and bicuspid
valves open for blood to be expelled into the ventricles
and pulmonary and aortic valve are closed to prevent
backflow of blood.
2. Ventricular systole – Ventricles contract, pulmonary and
aortic valves open for blood to be expelled into the
arteries (aorta and pulmonary artery) and the bicuspid
and tricuspid valves close to prevent backflow of blood.
 Diastole is a pause during which all parts of the heart relax
and atria fill with blood.
 With each beat the heart moves blood through the body.
 Complete contraction and relaxation of the heart produces
two-tune sound, lub-dub. The first tone, lub, heard is due to
the closing of the bicuspid and tricuspid valve as the
ventricles contract during systole. The second, dub, comes
from the closing of the semi-lunar valves when the heart is
relaxing during diastole.
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 The heart has its own blood supply, called coronary circulation, providing it with
oxygen and removing dissolved metabolic waste substances.
 A heart attack can be caused by a accumulation of fatty substances, cholesterol,
calcium and other substances that make up plaque.
 Plaque begins to build up in the inner linings of larger arteries of the body.
However it takes a very long time for this condition to become dangerous. This
process of plaque build up is called atherosclerosis.
 High blood pressure, cholesterol, diabetes or especially smoking can accelerate
this process.
 A heart attack can also be caused by a severe spasm or tightening of the coronary
artery, which can cut off blood flow to the heart.
 Obesity
 High blood levels of cholesterol
 Permanently raised blood pressure
 Excessive psychological and emotional distress.
UNAVOIDABLE RISK FACTORS
 Increasing age
 Men are more at risk than women
 It tends to run in the family
 Severe pain in the chest, neck and arm
 Sweating
 Faintness and sickness
 Tiredness
 Shortness of breath
 Anxiety
 A fast heart beat
 Low blood pressure
 A sense of indigestion
 Coronary by-pass surgery: coronary artery damaged by
atherosclerosis can be by-passed using parts of an artery or a vein
taken from another part of the body.
 Heart transplant surgery: becomes necessary with severe heart
damage or complete heart failure. Not very common because of:
 Shortage of donors
 High costs
 Risk of rejection of the heart by the patients immune system.
Stroke condition where carotid arteries,
arteries supplying the brain with blood, are
blocked or rupture. They can be blocked by
plaque or a blood clot
 Hypertension
 Smoking
 Obesity
 High Cholesterol
 Diabetes
 Cardiovascular disease
 It tends to run in families
 Men are at a higher risk
 Increasing age
 Not smoking
 Exercising regularly
 Proper diet
 Taking aspirin
Usually surgery to open up the
carotid arteries to remove plaque or
blood clot. A stent maybe inserted to
support the artery.