Реферат: Cholesterol Essay Research Paper For years cholesterol
Cholesterol Essay, Research Paper
For years, cholesterol has been a major concern for millions of people around the world. This fear of cholesterol has led to many consultations with specialists like physicians and nutritionists. It seems that there is a great misconception about this molecule. A majority of the population is conscious of the harm that it can cause, but they are not aware that it has pertinent values to our body. There are two major forms that cholesterol comes in: 1) low density lipoprotein, which is generally considered “bad” cholesterol and 2) high density lipoprotein, which is known as “good” cholesterol. Although given these names, there is nothing inherently good or bad about them. This research will clarify a lot of the misconceptions that are associated with cholesterol and the overall effect that cholesterol has on the human body.
Cholesterol is a soft, fat like substance made up of carbon, hydrogen, and oxygen, that is found in all the body’s cells and is used to form cell membranes, manufacture hormones and other necessary substances. It is an organic compound belonging to the sterol family that also encompasses steroids.
Cholesterol is produced two ways. The first is by the liver. “The liver produces about 50,000,000,000,000,000 cholesterol molecules a second” (Body Mechanics 1), or about 1,000 mg of cholesterol a day. The second is by the intake of the foods eaten like animal fats (saturated and polysaturated fats) such as cheese, lard, egg yolks, red or marbled meat, pork, processed meat, gravies, palm or coconut oil, deep fried foods, whole milk, butter, etc… This second process is accountable for another 400 mg – 500 mg of cholesterol a day.
Once eaten, the cholesterol in the food goes into the intestines to await digestion. “Chylomicrons (fatty particles containing mainly triglycerides, but also cholesterol, phospholipids and protein) are produced in the intestinal wall” (Arthersclerosis 3). Once the chylomicrons enter the bloodstream, they bind to receptors on the capillaries. A large percentage of triglycerides is broken down and released into circulation. “The remainder of the chylomicron (the ‘chylomicron remnant’), now richer in cholesterol, continues in circulation until it reaches the liver and is absorbed (Athersclerosis 3). Since cholesterol is like a fat, it is hydrophobic and unable to mix with water or blood. In order for it to be carried through the blood, the liver the combines the cholesterol with triglycerides and proteins (called lipoproteins) to form packages called very low density lipoproteins (VLDL). These packages, which account for 10-15 percent of the cholesterol in the body, are dispersed into the bloodstream and are “transported to tissue capillaries where triglycerides are broken down and either used for energy or stored by muscle or fat cells” (Athersclerosis 3). After the release of the triglycerides, the package now has a higher percentage of cholesterol. This package is now called low density lipoproteins or “LDL”.
LDL’s, also known as the “bad” cholesterol, is transported through the bloodstream to build cells, make hormones, and act as an insulation for nerves. Low density lipoproteins account for “60-70 percent of the total serum cholesterol” in the body (ATP: Chapter 1 1). This package of cholesterol is very useful to the body. It is necessary in the membranes of cells. If the cell gets too cold, the cholesterol kept the cell from freezing or turning solid. Conversely, as the cell gets too hot, the cholesterol keeps the cell from melting. This so called “bad” cholesterol, maintain the cell’s fluidity. Once the LDL’s have completed their tasks, they are removed from the body though the bloodstream to the liver. However, this removal process can occur at slower rates in certain people than others. This causes a build up of the cholesterol within the walls of the arteries. This build up, over time, can slow down or even prevent the circulation of blood to the heart and brain and can cause such disorders as Atherosclerosis, in which “deposits of cholesterol and other fatty substances circulating in the blood accumulate in the interior walls of the blood vessels”, and hypercholesterolemia, which is an elevated level of cholesterol in the blood, and ultimately coronary heart disease (CHD), which causes heart attacks (Britannica Online 1). This is where the LDL’s get their “bad” reputation.
In addition to VLDL’s and LDL’s, there is another form of lipoprotein called high density lipoprotein or “HDL”. This package, which counts for 20-30 percent of the bodies total blood cholesterol, is also synthesized in the liver but it contains a higher percentage of triglycerides and a lower percentage of cholesterol. It is believed by many researchers to be “good” cholesterol because whereas low density lipoproteins are sent through the bloodstream to the different parts of the body that needs the cholesterol, the HDL’s are sent through the bloodstream to collect the excess cholesterol, take it away from the arteries, and bring it back to the liver where it is broken down, reprocessed, or excreted. This process decreases the accumulation of cholesterol in the arteries which in turn reduces the risk of heart disease, which is where HDL’s get their reputation of being the “good” cholesterol.
Both LDL’s and HDL’s are relatively safe as long as their levels found in the body do not exceed what is recommended. When getting cholesterol checked by a physician, there are two variables that are looked at: 1) the concentration of total cholesterol in the blood, and 2) the HDL cholesterol in your blood. According to the American Heart Association (AHA), below 200 mg/dL (milligrams per deciliter of blood) is the desirable measurement for total cholesterol. With this reading, the risk for a heart attack is relatively low and should be checked every five years. A reading of between 200 and 239 mg/dL, which is the average for most Americans, is borderline to high blood cholesterol according to the AHA. Someone with this reading is at twice the risk of a heart attack than someone with a reading of 200 mg/dL, and should change or modify your diet and do physical activity 3-5 times a week. They should also get their levels rechecked at least every other year. The third measurement bracket is above 240 mg/dL. This reading is considered high blood cholesterol by the AHA. Someone with this reading is in serious risk of a heart attack, and should work very closely with a physician to work out a program to reduce this reading.
When checking the HDL cholesterol in the blood, a desirable reading would be above 35 mg/dL. For Americans, the average level is between 45 and 65 mg/dL. There is evidence that shows that for every 1 mg/dL decrease in HDL, your risk for heart disease increases by 2 to 3 percent. Another way to measure the HDL in the blood is by a “cholesterol ratio”. This is determined by taking the total cholesterol in the blood and dividing it by the HDL level in the blood. According to the AHA, a safe ratio is below 5:1, with the ideal ratio being 3.5:1.
There are many factors that can lower the LDL in the blood. The first is the diet. Cutting down on saturated fats in a diet can decrease your total cholesterol ratio. Eating healthier, like using unsaturated fats such as corn, peanut, safflower, olive, and soybean oils can raise HDL levels in the body. Other safe foods are: lean meats, skinless chicken, beans, fruit, low fat milk, grains, fish, substituting eggs with egg beaters, margarine, etc… Cigarette smoking is another factor that can raise LDL build up. Another problem is smoking. Smoking causes the heart to beat and pump harder, which is able to push LDL’s into the arteries easier than nonsmokers to cause a build up. The cholesterol levels are higher in men than in women. There is evidence that has shown that women during their childbearing years have a much lower level of cholesterol than men. The estrogen that is produced before menopause lowers the risk of high cholesterol. After menopause, women’s risk of CHD increases.
In conclusion, both LDL’s and HDL’s are neither good nor bad. They each have a specific purpose and function that is vital to the human body. Only when excessive amounts are taken, do they present a risk to the health of a human. Watching what is eaten, exercise, and regular testing can assure a long and healthy life without the concern of cholesterol.