The Lungs
These are the organs used to exchange air between the blood and the external environment.
Air passes from the environment to trachea or wind passage and through to the bronchi, which divide I to the two lungs. Within each lung, each bronchus divides and subdivides, ending in air sacs called alveoli. It is the alveoli which effect the passage of oxygen into and carbon dioxide out of the blood stream.
The Heart
The heart is a muscle that acts as a pump to circulate blood through the body. It does this at a rate of approximately 72 beats per minute in the average middle-aged male (80 bpm for female), each beat being called a pulse.
The heart, lungs, muscles and organs are connected by veins and arteries that allow blood to be cycled from the lungs, around the body and back again to the lungs for replenishing with oxygen and disposal of wastes.
The fact that the heart is called upon to supply more blood to an exercising muscle than a resting muscle is important to the fitness, because it means that pulse rate can be used as a means of determining the individual`s response to exercise and an exercise program can be planned accordingly.
MAJOR PROBLEMS OF THE CARDIOVASCULAR SYSTEM
Coronary Artery Disease
A heart attack (myocardial infarction) results when an artery carrying blood to the heart muscle (coronary artery) becomes blocked. This generally occurs in the presence of partial blockage caused by a disease called atherosclerosis.
Atherosclerosis
is a build up of fats (cholesterol in particular) and fibrous material on the lining of the arteries. This build up is gradual and take place over a person's lifetime. When complete blockage occurs, and this is usually a sudden event, a part of the heart muscle loses its blood supply and dies, hence the term myocardial (heart muscle) infarction (death of tissue).
Angina pectoris
Is an episode of chest pain or discomfort that may radiate to the neck or jaw, or down either arm to tbe elbow. It signifies the heart muscle is not receiving sufficient oxygen-rich blood for its immediate needs. Angina usually occurs during physical exertion, emotional arousal or even after a heavy meal where the heart is having to work harder. Angina is not a heart attack but is often considered a precurser to a heart attack. Reducing exercise intensity, or medication in the form of nitroglycerine, usually relieves it.
Thrombosis
Is the blockage of blood vessel by a blood clot. It is most likely to occur in the presence of atherosclerosis, but also occurs when blood flow is sluggish.
Coronary thrombosis
Occurs when a clot may block off blood flow to part of the heart, which may cause the affected part to die. If more than 30% of the heart muscle is damaged death may result. On the other hand, damage to less than 5% may go unnoticed.
Stroke affects the brain - not the heart
It is included here because both stroke and coronary heart disease often share the same underlying causes. A stroke occurs when the blood supply to a part of the brain is either cut off or significantly reduced. When this occurs, part of the brin is starved of oxygen, causing cell damage which may result in paralysis, impaired speech, etc.
Valvular disease
The heaart has valves which allow blood to flow in one direction but not the other. If these valves become damaged the normal passage of blood flow is interrupted. The damage can often be detected by heart murmur or a whooshing sound which is clearly audible through a stethoscope.
Arrhythmia
When heart muscle is impaired by an oxygen shortage, the neural stimulation to the cardiac muscle can be affected. This can cause extra heart beats and non rhythmic muscle contractions that interfere with pumping efficiency.
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