Bio+Passage+12+PDF

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Abilene Christian University *

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112

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Mechanical Engineering

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Dec 6, 2023

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Passage (Questions 39-43) One of the most common age-related changes to the heart is valvular calcification, especially of the aortic and mitral valves. As the valves calcify, the caliber of the valves becomes smaller, resulting in changes in the dynamics of how blood flows within the heart. One of the ways in which the dynamics of flow within the heart can be measured and graphed includes pressure-volume loops. A pressure-volume loop has pressure on the y-axis and volume on the x-axis. The pressures and volumes of the left ventricle are measured during a single cardiac cycle and graphed. Examples of pressure-volume loops in aortic and mitral stenosis are shown below. Aortic _4 Stenosis LVP (mmHMg) Control LVV (ul) Figure 1 Aortic Stenosis pressure-volume loop Mitral Stenosis LVP (mmHg) Control Loop gfi——- LVV (ul) Figure 2 Mitral Stenosis pressure-volume loop A researcher conducted a study comparing the volumes of the left atrium and left ventricle between 50 women with normal valvular function, mitral stenosis, and aortic stenosis. Results are summarized in the following table. Group Average Left Atrial Volume | Average Left Ventricular Diastolic Volume Normal Valves 47.8cm° +12.8 48.6 cm® + 11.6 Aortic Stenosis 73.2cm° £ 24.2 156.3 cm® + 22.6 Mitral Stenosis 78.6 cm® + 18.6 52.3 cm® + 10.9 Table 1 Average volume for atrium and ventriculum for different patient populations

Question 39 Which of the statements is only representative of aortic stenosis? O A. Left ventricular volumes are lower than expected. O B. Left ventricular pressures are lower than expected. O €. Stroke volume is reduced at lower left ventricle pressures. O D. Left ventricle pressures are higher at lower stroke volumes. Question 40 Which of the following conclusions can reliably be drawn from the data in Table 1? O A. Mitral stenosis causes the largest increase in left atrial volume. O B. Aortic stenosis causes the largest increase in left atrial volume. O €. Mitral stenosis causes the largest increase in left ventricular volume. O D. Aortic stenosis causes the largest increase in left ventricular volume. Question 41 Which of the following subject groups should be excluded from the subjects in the study described in the passage? O A. Subjects with aortic stenosis for 10 years O B. Subjects with both aortic and mitral stenosis O C. Subjects with mitral stenosis for 5 years O D. Subjects with normal valvular function

Question 42 Which of the following nervous system changes would be expected in a patient with aortic stenosis? O A. Increased parasympathetic nervous system activity O B. Increased sympathetic nervous system activity O €. Decreased autonomic nervous system activity O D. Increased cortical coordination of cardiac activity Question 43 Regurgitation is a condition that results from an incompetent valve. Regurgitation of which valve is likely to be directly responsible for dilation of the right ventricle? O A. Aortic valve O B. Mitral valve O €. Pulmonic valve O D. Tricuspid valve

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