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Explain how arteries, veins, and capillaries are adapted for their functions. Describe what happens in coronary heart disease and explain how lifestyle may contribute to the development of this disease.

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Introduction

Explain how arteries, veins, and capillaries are adapted for their functions. Describe what happens in coronary heart disease and explain how lifestyle may contribute to the development of this disease. The human circulatory system is an essential network of tubes designed to transport a continuous flow of blood throughout the body delivering nutrients to and removing waste from every cell. Contemporary society is experiencing an increasing number of people suffering from an often preventable disease that occurs in this circulatory network named coronary heart disease. (Boyle, M., Senior, K. 2002). (www.nhlbi.nih.gov/health/public/heart/other/chdfacts.htm). This essay will explain how the circulatory systems' arteries, capillaries and veins are adapted for their functions, what happens in coronary heart disease, and how some contemporary lifestyles may contribute to the condition. The main organ of the circulatory system is the heart, situated in the chest between the lungs. It is a hollow muscular structure consisting of four main chambers. The lower left and right ventricles have thick muscular walls to pump blood, and the upper left and right atria that have thinner walls and receive blood. This is effectively a double circulatory system as both ventricles pump blood and both atria receive blood simultaneously. ...read more.

Middle

Although veins have the same composition as arteries, they have a much thinner layer of tunica adventitia and tunic media, as blood pressure is much lower. This structure has a wide lumen to reduce resistance in blood flow allowing for easier expansion and adapting them for their function as a reservoir for blood. To prevent the downward pull of gravity resulting in an accumulation of blood in the lower part of the body, the veins contain one-way pocket valves. In addition to this, the contracting of the skeletal muscles press against the veins narrowing them so creating pressure which forces the blood towards the heart. During inspiration, reduced pressure in the thorax encourages blood to flow towards the heart. The pocket valves prevent back flow during expiration when thoracic pressure is high. (www.medem.com/The Vascular System). (Boyle, M., Senior, K. 2002). The coronary arteries are an extensive network of vessels that supply the myocardium or heart muscle itself. Coronary heart disease (CHD) or ischaemic heart disease is the most common and the most preventable of all heart disease and it occurs in this particular network. The main risk factors are high blood cholesterol, hypertension, smoking, obesity, diabetes mellitus, physical inactivity or the genetic predisposition familial hyperlipidaemia. ...read more.

Conclusion

(Eades, M.R., Eades, M.D. 2000). (British Heart Foundation, Eating for your Heart, 1999). Regular physical activity raises HDL but does not affect LDL and can help to maintain a healthy weight and reduce obesity, hypertension and medication required for diabetes mellitus. It can also help to prevent hypertension and thrombosis by ensuring the artery walls are kept supple and less prone to the thickening that reduces the lumen, elevates pressure and increases the risk of damage to the endothelial cells. (British Heart Foundation, Physical Activity and your Heart, 1999). (Boyle, M., Senior, K. 2002). Cigarette smoke contains a vasoconstrictor nicotine that narrows the blood vessels increasing blood pressure. It also increases lipoproteins in the blood and the amount of fibrinogen, which causes the blood to clot. (Boyle, M., Senior, K. 2002). By reducing saturated fats, stopping smoking, increasing physical activity and generally eating a healthy balanced diet will reduce the risks of developing CHD. Unfortunately, the disease is still on the increase in developed countries and is a major killer. Luckily, there are many safe drugs available that can control symptoms or reduce them but, as an escalating problem, lifestyle changes are the safest, cheapest and healthiest ways of reducing or eliminating the risks. (Boyle, M., Senior, K. 2002). ...read more.

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Here's what a teacher thought of this essay

4 star(s)

This is a very good essay that outlines the structures and functions of the major blood vessels. It also discusses, symptoms, causes and risks of developing CHD. It would however benefit from diagrams to reinforce the text and develop the concept further. The references used were sometimes old and as science is so fast moving more recent references would have been beneficial.
4 stars.

Marked by teacher Louise Star 09/07/2013

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