Cardiovascular System

The primary function of the cardiovascular system is to distribute and collect blood in all parts of the body. It consists of a pump (i.e., the heart) and a network of viscoelastic tubes (i.e., the aorta, arterioles, capillaries, venules, veins, and the superior and inferior vena cavae) (Detweiler, 1979, p. 33). In order to maintain adequate perfusion of the body's many organs and tissues, both blood pressure and blood flow must be intricately controlled. In general, all blood flowing through the aorta must also flow through the capillaries and veins. Although such flow is, hence, governed by the law of equality, the hydrostatic pressure in each of the three types of vessels is markedly different. For example, blood pressure is typically highest in the aorta, intermediate in the arteries, and low in the capillaries and veins. Thus, as blood flows throughout the body, the hydraulic energy provided by the heart is gradually dissipated via friction and heat (Detweiler, 1979, p. 33). The rate at which this loss occurs depends on vessels' resistance to blood flow. These relationships can be written as follows:

Volume flow (V) = Pressure gradient (P) / Resistance (R)

This formula is equivalent to Ohm's law of electrical circuits, i.e., I = E/R. Although it may be extremely useful for describing the direct relationship between blood pressure and blood flow, it fails to account for ei

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more strongly and pump out a greater amount of blood per beat" (Tokay, 1970, p. 61). Conversely, it may be assumed that whenever the supply of venous blood is decreased, the heart will pump out a lesser amount of blood per beat. Within the intermediate range of heart rate values, slower rates increase the amount of time spent in diastole, increase ventricle dilation, and ultimately cause the heart to beat more powerfully. In addition, within the same range of values, higher rates result in shortened diastole, a decrease in ventricle dilation, and a less powerful beat. These adjustments serve to enhance the body's physiological functioning. Regardless of the body's particular heart rate, cardiac output is maintained at a relatively constant level. Thus, heart rate, end-diastolic volume, and force of contraction are all closely related. Moreover, these characteristics of cardiac function are highly regulated. Each is modulated such that the heart pumps a quantity of blood sufficient to meet the body's physiological requirements (Tokay, 1970, p. 65). D. Explain the elevation of pulmonary capillary pressure that occurs in left heart failure. The clinical syndrome, chronic congestive heart failure, can be characterized as
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Some common words found in the essay are:
Harrison Resnik, Starling Curve, SV Katz, , According Laplace, Celsius West, O2 Hb, According Laplace's, PO2 Murray, M Wintrobe, blood flow, heart rate, cardiac output, heart failure, detweiler 1979, surface tension, katz 1992, oxygen dissociation, coronary artery, heart rates, oxygen dissociation curves, congestive heart failure, left heart failure, coronary artery perfusion, oxygen dissociation curve,
Approximate Word count = 5254
Approximate Pages = 21 (250 words per page)

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