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The cause and consequences of atherosclerosis and hypertension and the use and action of Beta blockers.

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Introduction

Rohit Gumber The cause and consequences of atherosclerosis and hypertension and the use and action of Beta blockers. As animals grew in size and complexity, the need arose for a system to transport materials, especially food, oxygen, carbon dioxide and wastes. This system must service every cell in the body. In humans, this is achieved by having capillaries within diffusing distance of them. The fluid is circulated by a specialised pump - the heart. The blood is circulated around the body in vessels called arteries and returned to the blood by veins. Arteriosclerosis is a chronic disease caused by the abnormal thickening and hardening of the arteries, with a resulting loss of elasticity. The major form of arteriosclerosis is atherosclerosis. Atherosclerosis is a disease of both large and medium sized arteries, in which plaques of fatty deposits, or atheromas, form on the inner walls of the arteries. In atherosclerosis, cholesterol-carrying lipoproteins in the circulating blood are gradually deposited on the inner linings of arteries over a period of years. As more cholesterol is deposited on the lining, initially tiny lesions enlarge and thicken to form plaques, narrowing the vessel channel and interfering with the flow of blood through it. ...read more.

Middle

Over time, this higher pressure, or hypertension, can damage the arterioles (the small terminal twigs of an artery that end in capillaries) in such organs as the liver, kidney, or brain and can also weaken the overworked heart. The increased risk of death from congestive heart failure, kidney failure, or stroke is the chief danger of hypertension. (Microsoft, 1996, Encarta 97 Encyclopedia) From Heartpoint: High Blood Pressure Information I found that 90 percent of people who have high blood pressure have something called essential hypertension. This type of high blood pressure has no known cause. However, studies have pointed out several contributing factors. Included among these are family history, obesity, high salt intake, smoking, high alcohol consumption, and emotional and physical stress. Another type of high blood pressure that occurs is called secondary hypertension. This may result from a wide range of uncommon causes * A number of kidney diseases cause high blood pressure. * Disorders of the adrenal glands: * Pheochromocytoma, This tumour produces adrenaline and/or similar substances. Patients with this disorder typically have spells of high blood pressure which are accompanied by strong and rapid heart beats, sweating and headaches. ...read more.

Conclusion

Therefore, blocking the beta 1 receptor (and all beta blockers block the beta 1 receptor) results in the heart rate slowing down and the heart beating less forcefully. This causes the heart to require less oxygen, less blood is ejected from the heart, and blood pressure is lowered. Beta blockers are a fundamental treatment in myocardial infarctions ("Heart Attacks"). The main beta 1 selective drugs used are metoprolol (Lopressor) and atenolol (Tenormin). These drugs do not allow the hormones that cause the blood vessels to constrict (norepinepherine and epinephrine) bind to their site on the blood vessel. Because these hormones cannot bind, the blood vessels do not contract and the blood pressure is lowered. Stimulating the beta 2 receptor causes smooth muscle (muscles that control body functions which you do not have control over) to relax. This means that lungs relax (bronchodilation), uterus relaxes, and arterioles (a type of blood vessel) relax. They also cause skeletal muscles (as in biceps, triceps, etc.) to become activated and large. Therefore, drugs which block the beta 2 receptor have adverse effects and uses in addition to the effects mentioned for beta 1 blockade. The classic non-selective beta blocker is propranolol (Inderal). Other examples include: Nadolol Acebutolol Labetolol (About Beta Blockers - Marshall U. ...read more.

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