Pernicious anemia results when the person's stomach fails to produce intrinsic factor, which is necessary for the normal absorption of vitamin B-12.

Leukemia

A great increase in abnormal leukocytes may occur for unknown reasons, resulting in the diseases known as the leukemias. These range in severity from the chronic lymphocytic leukemia, in which a person may live for many years, to devastating acute leukemia, often causing death within months.

Thromboembolic Disease

A more common disease is abnormal clotting in the blood vessels, known as thromboembolic disease. This group of disorders, caused by a relatively inactive lifestyle, or by a person's confinement to bed, is one of the most common causes of death in middle-aged and elderly persons.

Heart Diseases

Heart attacks are the number-one cause of death in the United States. Cardiovascular diseases are the leading cause of death worldwide. Cardiovascular diseases include a wide range of disorders that affect the heart and the blood vessels and are the product of many factors, which range in nature from hereditary to nutritional and environmental. Because capillaries are the site where oxygen and nutrients enter body cells and waste products are removed by the bloodstream, any peripheral vascular disease will affect the function of the tissues supplied by the capillaries. Cardiovascular diseases can therefore cause disease in all other tissues and organs of the body.

Artery Diseases

The single major cause of artery disease is the thickening and hardening of arterial walls by deposits of fatty materials, known as arteriosclerosis. In major vessels such as the aorta, this process is called atherosclerosis.

Atherosclerosis

Atherosclerosis is a disorder of large and medium-sized arteries, such as the large coronary arteries that supply the heart muscle with oxygen. The disorder is characterized by a buildup of fatty deposits, called plaques, on the inner walls of arteries. These yellowish plaques consist of materials such as cholesterol, lipids, and cellular debris. They lead to a loss of elasticity in the artery and to ischemia, or a narrowing of the blood's passageway. The resulting decrease in smooth blood flow may ultimately deprive a vital organ, such as the heart or brain, of its blood supply. Loss of circulation to a limb may also occur.

Atherosclerosis is the most common cause of coronary heart disease, including heart attacks. It is also a major cause of stroke. Half the mortality in Western societies results from heart and blood-vessel diseases, of which atherosclerosis, the most common lethal disease, is the major cause.

The causes of atherosclerosis are not yet fully understood, but certain characteristics called risk factors tend occur in persons prone to atherosclerosis. These include high blood pressure, or hypertension, and high blood-cholesterol levels. Resistance to these factors appears to diminish with age, especially when accompanied by obesity and cigarette smoking. Atherosclerosis may also be manifested fairly rapidly in diseases such as diabetes, in which the concentration of blood lipids is raised.

Medical evidence indicates that a low fiber diet high in saturated fats tends to promote atherosclerosis; while a healthy diet rich in antioxidants, regular exercise, and avoidance of smoking and hypertension can delay atherosclerosis, even in persons prone to the disease.

Atherosclerosis may result in occlusion or blockage of an artery. In many cases the cause of the blockage is a clot formation in a narrowed atherosclerotic area. In the coronary arteries this is the major cause of myocardial infarctions, or heart attacks. In peripheral arteries, such as those of the legs, severe narrowing can result in gangrene and can lead to surgical amputation. Since the condition appears to be accelerated in patients with diabetes mellitus, gangrene of the lower extremity is a significant danger for these persons.

Bypass surgery, the surgical replacement of the narrowed segment of artery with a vein taken from elsewhere in the body, is a common medical treatment for arterial narrowing in coronary arteries. However, this procedure has been proven to be both dangerous and mostly ineffective. Statistically, patients who receive bypass surgery do not live any longer than those who choose not to receive the surgery. Additionally, the new artery has a much greater chance of developing atherosclerosis.

Another medical therapy, angioplasty, is the dilation of the narrowed segment with a tiny balloon delivered by catheter. It has been demonstrated that this procedure also has very limited, if any, benefit. It is also a dangerous procedure since there is a significant risk of death by heart attack while the procedure is being done.

Aneurysms

Other major diseases of the aorta include true aneurysms and so-called dissecting aneurysms. The former are balloon-like swellings that result from weakening of the aorta wall, most commonly because of atherosclerosis. Dissecting aneurysms are thought to be the result of an inherited degeneration of the middle layer of the aorta wall, leading to a separation (a dissection) of the layers by blood, under high pressure, pouring through a tear in the inner layer. A danger in any aneurysm is rupture and sudden death. Additionally, true aneurysms may cause severe symptoms by exerting pressure on nearby structures.

Vein Diseases

The most important peripheral vascular disease of the veins is thrombophlebitis or phlebitis. This disorder involves the formation of a blood clot (or clots) in large veins, usually in the leg or pelvis. Any or all of three major factors can cause such clots: slowing of the bloodstream (or even stoppage for a short period of time), increase of coagulability of the blood, and injury to the lining of the vein. The disorder can cause local inflammation, redness, and swelling, but it may also be entirely free of local symptoms. In either case, but particularly in the latter one, the clot may break off and travel to the right side of the heart. From there it is pumped to the lung where it is trapped as the pulmonary artery branches and narrows, blocking the blood supply to a portion of the lung, a process called pulmonary infarction. The immediate shock may be fatal and is one of the major causes of sudden death in postoperative hospitalized patients. To prevent such an occurrence postoperative patients are constantly monitored and encouraged to walk as soon as possible.

A distressing but usually minor disorder of the veins, known as varicose veins, results from a failure of valves in the veins to keep blood flowing back toward the heart. In some cases, however, the condition can lead to varicose ulcers or the inflammation of vein walls, with resulting development of clots and of thrombophlebitis.

Hypertension

High blood pressure is a common disorder that affects up to 20 percent of the adult population in the United States. By far the most common type is essential hypertension, the causes of which are medically unknown. The remaining cases of high blood pressure are secondary to at least 30 different conditions. High blood pressure is often secondary to hardening of the arteries. As the arteries lose their elasticity, the heart has to beat harder to force the blood through. The result is high blood pressure. Untreated hypertension can cause severe kidney damage, precipitate a cerebral hemorrhage (stroke), or result in heart failure.

Stroke

Stroke, also known as CerebroVascular Accident (CVA), involves damage to the brain because of impaired blood supply and causes a sudden malfunction of the brain. In the United States, stroke is the third-ranking cause of death after heart disease and cancer, and about one-fourth of the neurologic patients in nursing homes are stroke victims.

Stroke victims are generally elderly people with degeneration of blood vessels, but children and young adults also can have a stroke. Some stroke risk factors include increasing age, gender (more men have strokes), diabetes mellitus, prior stroke, and family history of stroke, hypertension, heart disease, cigarette smoking, high cholesterol, and transient ischemic attacks (TIAs), or little strokes. Women using oral contraceptives also tend to have more strokes.

The risk factors for stroke include ________.

smoking
diabetes mellitus
hypertension
high cholesterol
all of the above

(Select the best answer and click on the "Continue" button.)

       

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