The Heart Essay Research Paper CONTENTS3 — страница 4

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As their size decreases, so do their concentration of triglycerides, but the smaller they are, the more cholesterol they contain. Pre- beta-lipoproteins are also known as low density lipoproteins (LDL), and beta lipoproteins are also called very low density lipoproteins (VLDL). They are most significant in the development of atheroma. The smallest lipoprotein particles, the alpha lipoproteins, contain a low concentration of cholesterol and triglycerides, but a high level of proteins, and are also known as high density lipoproteins (HDL). They are thought to be protective against the development of atherosclerotic plaque. In fact, they are transported to the liver rather than to the blood vessels. Lipoproteins and Atheroma The theory is that lipoproteins pass between the lining

cells of the arteries and some of them accumulate underneath. All except the chylomicra, which are too big, have a chance to accumulate. The protein in the lipoproteins are broken down by enzymes, leaving behind the cholesterol and triglycerides. These fats are trapped and set up a small inflammatory reaction. The alpha particles do not react with the enzymes are returned to the circulation. RISK FACTORS There are several risk factors that contribute to the development of atherosclerosis and angina: Family history, Diabetes, Hypertension, Cholesterol, and Smoking. Family History We all carry approximately 50 genes that affect the function and structure of the heart and blood vessels. Genetics can determine one’s risk of having heart disease. There are many cases today where

heart disease runs in a family, for many generations. Diabetes Diabetics are at least twice as likely to develop angina than nondiabetics, and the risk is higher in women than in men. Diabetes causes metabolic injury to the lining of arteries, as a result, the tiny blood vessels that nourish the walls of medium-size arteries throughout the body, including the coronary arteries, become defective. These microscopic vessels become blocked, impeding the delivery of blood to the lining of the larger arteries, causing them to deteriorate, and artherosclerosis results. Hypertension High blood pressure directly injures the artery lining by several mechanisms. The increased pressure compresses the tiny vessels that feed the artery wall, causing structural changes in these tiny arteries.

Microscopic fracture lines then develop in the arterial wall. The cells lining the arteries are compressed and injured, and can no longer act as an adequate barrier to cholesterol and other substances collecting in the inner walls of the blood vessels. Cholesterol Cholesterol has become one of the most important issues in the last decade. Reducing cholesterol intake can directly decrease one’s risk of developing heart disease, and people today are more conscious of what they eat, and how much cholesterol their foods contain. Cholesterol causes atherosclerosis by progressively narrowing the arteries and reduces blood flow. The building up of fatty deposits actually begins at an early age, and the process progresses slowly. By the time the person reaches middle-age, a high

cholesterol level can be expected. Smoking It has been proven that about the only thing smoking do is shorten a person’s life. Despite all the warnings by the surgeon general, people still manage to find an excuse to quit smoking. Cigarette smoke contains carbon monoxide, radioactive polonium, nicotine, arsenious oxide, benzopyrene, and levels of radon and molybdenum that are TWENTY times the allowable limit for ambient factory air. The two agents that have the most significant effect on the cardiovascular system are carbon monoxide and nicotine. Nicotine has no direct effect on the heart or the blood vessels, but it stimulates the nerves on these structures to cause the secretion of adrenaline. The increase of adrenaline and noradrenaline increases blood pressure and heart

rate by about 10% for an hour per cigarette. In simpler words, nicotine causes the heart to beat more vigorously. Carbon monoxide, on the other hand, poisons the normal transport systems of cell membranes lining the coronary arteries. This protective lining breaks down, exposing the undersurface to the ravages of the passing blood, with all its clotting factors as well as cholesterol. Multiple Risk Factors The five major risk factors described above do more than just add to one another. There is a virtual multiplication effect in victims with more than one risk factor. (Chart: Risk Factors) DIAGNOSIS It is very important for patients to tell their doctors of the symptoms as honestly and accurately as possible. The doctor will need to know about other symptoms that may distinguish