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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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.  

The pulmonary system starts in the right ventricle where deoxygenated blood is pumped via the pulmonary artery to the lungs.  Here it is reoxygenated and returned to the left atrium via the pulmonary vein.

The systemic system pumps the oxygenated blood from the left ventricle via the aorta.  The aorta branches into the carotid artery that serves the head and forelimbs, the hepatic artery the liver, the mesenteric artery the gut, and the renal artery the kidneys and lower limbs.  From the gut deoxygenated blood travels to the liver via the heptic portal vein.  From the kidneys and lower limbs, deoxygenated blood leaves via the renal vein and from the liver via the hepatic vein.  These veins join the inferior vena cava which in turn joins the superior vena cava carrying deoxygenated blood from the head and forelimbs and re-enters the heart through the right atria.   (Roberts, M.B.V. 1976).

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Arteries transport blood away from the heart at high pressure to supply the organs and body tissue with oxygen and nutrients required to maintain life.  Their walls have a thick muscular structure, which adapts them for high pressure and any change in pressure due to increased activity.

The outer walls, tunica adventitia are connective tissue and the inner walls tunica media, are elastic tissue forming smooth muscle.  A single layer of flattened endothelial cells form a smooth muscular tube within these walls.  This structure enables diastole and systole with each pulse of blood pumped by the heart.  Semilunar valves ...

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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.