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Atherosclerosis

Atherosclerosis is narrowing of arteries caused by accumulation of fatty deposits on the arterial walls.

On June 22, 2002 the St. Louis Cardinals were preparing for their upcoming baseball game against the Chicago cubs. Concern arose when their prized pitcher, 33-year old Darryl Kile did not show up for practice. Soon after, he was found still in his hotel room where he had suddenly died in his sleep (New York Times, 2002). It was discovered that the cause of death was related to three of his coronary arteries being 80-90% blocked as a result of atherosclerosis (New York Times, 2002), which ultimately caused him to undergo a heart attack.

Answer to the assignment questions:

1. Why would atherosclerosis result in a heart attack?

Atherosclerosis is a chronic focal disease of the arteries, characterized by accumulation of the lipid-containing proteins and cholesterol in the inner shell of the vessel, accompanied by the growth of the connecting tissue and the formation of the so-called atherosclerotic plaques. These plaques narrow the artery (which leads to stenosis – narrowing of the arteries) which results in development of a chronic shortage of blood supply to the body organs. (Maton,1993)

The basis of the pathological process in atherosclerosis is the defeat of blood vessels that causes secondary disorders of blood circulation and blood supply to the internal organs. There is also possible an acute blockage (occlusion) or the vessel with thrombus or with the broken plaque. The gradual artery atherosclerosis develops slowly and begins almost from birth, and the first clinical signs of disease (pain in heart, heartbeat, high blood pressure and others) occur in the working-age adults. Sometimes the disease leads to acute myocardial infarction or stroke, which results in disability or death. (Maton,1993)

Nowadays the most wide is the theory of the lipid atherosclerosis, which stresses the leading role of lipoproteins of different classes, and especially cholesterol, in the development of biochemical and morphological changes in the arterial wall, the ultimate manifestation of which is the formation of atherosclerotic plaque. It is assumed that increase in the level of cholesterol in the blood plasma to 1% greatly increases the risk of coronary heart disease and other manifestations of atherosclerosis.

2. Blood circulation. How are arteries different from veins and capillaries? Describe the functions of both.

Blood is the most important means of transport of substances through the body, as blood circulates in the blood vessel system, covering all agencies. Circulation is the primary objective function of the heart, as the heart acts as a pump, which alternately compresses and sucks blood. Blood moves through vessels resulting from rhythmic heart beat and the pressure difference in various parts of the circulatory system, while rhythmic heart function creates and maintains the pressure difference in the vessels. When pressure increases, the blood flow in large arteries of the general circulation, and when the pressure decreases, the blood from large veins enters the atrium. (Tortora, 2000)

Arteries are blood vessels that carry blood from the heart. They are cylinder tubes in which blood flows from heart to organs and tissues. The nervous system controls muscle cells in artery walls: if they are compressed, the diameter of the arteries decreases and less blood flows through them. Arteries must rich all the parts of the body, so they are divided into arterioles and then branch out and become capillaries – the smallest blood vessels, which “penetrate” into all the body tissues. After passing through the capillaries, blood flow increases again in the cross section and passes through the venules, which form small veins and larger veins (large veins carry blood back to the heart). (Van De Graaff, 2003)

The difference between veins and arteries lies in the walls thickness, since the walls of veins are thinner than of the arteries. Another difference is related to blood pressure, which is significantly lower in veins, and the volume of blood flowing in the veins is much greater than in the arteries.

3. Briefly explain how the lymphatic system is associated with the circulatory system? Describe one disease that affects the lymphatic vessels

A special role in the circulation has the lymphatic system, which is a complex system of vessels with lymph nodes. The lymphatic system along with the veins provide the absorption of tissue: it complements the circulatory system, removing excess fluid in the blood, accumulating in the tissues. Along with the veins of the body lymph vessels carry the drainage function. (Tortora, 2000)

The most clinically significant disease of lymphatic vessels is lymphedema. There are primary and secondary forms of the disease. Primary lymphedema in 4% of cases is hereditary, and in 94% cases is sporadic, due to hypoplasia or aplasia of the lymphatic vessels. In secondary lymphedema the causes of violations of lymph drainage are inflammation, trauma, surgical surgery associated with damage or removal of lymph nodes.

References:

“Baseball: Coroner Verifies the Cause of Kile’s Death as Natural” (2002, July 17). The New York Times. Retrieved: http://www.nytimes.com/2002/07/17/sports/baseball-coroner-verifies-the-cause-of-kile-s-death-as-natural.html?ref=darryl_kile
Tortora, G. & Grabowski, S. (2000). Principles of Anatomy & Physiology. Wiley & Sons
Van De Graaff, Kent M. (2002). Human Anatomy. McGraw Hill Publishing
Maton, A. et al (1993). Human Biology and Health. Englewood Cliffs, New Jersey, USA: Prentice Hall.