EVOLVE CH 31

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University of Texas, El Paso *

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5319

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Biology

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Feb 20, 2024

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1. 1. 1. ID: 25066824811 Which cardiac chamber has the thickest wall? A. Left atrium B. Right atrium C. Left ventricle Correct D. Right ventricle Incorrect The atria are approximately 1–2 mm thick. The right ventricle is 4–5 mm thick, and the left ventricle, the most muscular chamber, is approximately 12–15 mm thick. Awarded 0.0 points out of 1.0 possible points. 2. 2. ID: 25066824816 Which statement accurately describes blood flow through the heart? A. Blood flows from the left atrium through the tricuspid valve to the left ventricle. B. Blood flows from the right atrium through the aortic valve to the right ventricle. Incorrect C. Blood flows from the right ventricle through the pulmonic semilunar valve. Correct D. Blood flows from the left ventricle through the bicuspid valve. Blood flows from the right atrium through the tricuspid valve to the right ventricle. Blood then travels from the right ventricle through the pulmonic semilunar valve to the pulmonary circulation. Once in the pulmonary circulation, it is oxygenated and travels to the left atrium through the bicuspid valve to the left ventricle. Blood leaves the left ventricle through the aortic valve and enters the systemic circulation. Awarded 0.0 points out of 1.0 possible points. 3. 3. ID: 25066824821 Which statement correctly describes the A wave? A. The A wave is generated by atrial contraction. Correct B. The filling of the atrium causes early diastolic peak of the A wave. C. The A wave is produced as a result of the descent of the tricuspid valve ring. D. The A wave reflects the rapid flow of blood from the great veins and right atrium into right ventricle. The A wave is generated by atrial contraction. The V wave is the early diastolic peak caused by the filling of the atrium. The X descent follows the A wave and is produced because of the descent of the tricuspid valve ring. The Y descent follows the V wave and reflects

the rapid flow of blood from the great veins and right atrium into the right ventricle. Awarded 1.0 points out of 1.0 possible points. 4. 4. ID: 25066824826 Which artery travels in the coronary sulcus between the left atrium and the left ventricle? A. Left anterior descending Incorrect B. Circumflex Correct C. Right coronary D. Left coronary The circumflex artery travels in the coronary sulcus. The left anterior descending artery travels down the anterior surface of the interventricular septum. The right coronary artery originates from an ostium behind the right aortic cusp and travels behind the pulmonary artery. The left coronary artery passes between the left atrial appendage and the pulmonary artery and generally divides into two branches. Awarded 0.0 points out of 1.0 possible points. 5. 5. ID: 25066824831 Which part of the heart is responsible for electrical impulse stimulation? A. Atrioventricular node Incorrect B. Sinus node Correct C. Bundle of His D. Right bundle branch The sinus node, the pacemaker of the heart, is the site of impulse formation. The atrioventricular node is the junction of the electrical transmission between the atria and the ventricles. The impulse then travels to the bundle of His and, finally, to the right and left bundle branches. The terminal branches are the Purkinje fibers. Awarded 0.0 points out of 1.0 possible points. 6. 6. ID: 25066824836 Which cardiac event represents the measure of time from the onset of atrial activation to the onset of ventricular activation? A. PR interval Correct B. QRS complex C. ST interval D. QT interval The PR interval measures the time of onset of atrial activation to the onset of ventricular activation. The QRS complex represents the sum of all ventricular muscle cell depolarization. The ST interval is the time when the entire ventricular myocardium is depolarized. The QT interval is often called electrical systole.

Awarded 1.0 points out of 1.0 possible points. 7. 7. ID: 25066824841 Which two items are related in the Frank-Starling law of the heart? A. Resting sarcomere length to tension generation Correct B. Resting sarcomere length to end-diastolic volume C. Tension generation and left ventricular pressure D. Tension generation and diastolic filling pressures The Frank-Starling law of the heart relates resting sarcomere length (expressed as the volume of blood in the heart at the end of diastole or end-diastolic volume) to tension generation (development of left ventricular pressure). In summary, this means the volume of blood in the heart at the end of diastole is directly related to the force of contraction of the next systole. Awarded 1.0 points out of 1.0 possible points. 8. 8. ID: 25066824846 Which statement correctly defines preload? A. Resistance to the ejection of blood from the left ventricle B. Wall tension that is related to internal blood vessel radius C. Pressure generated by atrial contraction Incorrect D. Pressure generated by the end-diastolic volume Correct Preload is the pressure generated in the left ventricle at the end of diastole (end-diastolic volume). Afterload is the resistance or impedance to the ejection of blood from the left ventricle. Wall tension is directly related to the product of the intraventricular pressure and internal radius, and inversely related to the wall thickness (Laplace’s law). A tension curve lower than normal is characteristic of congestive heart failure. Awarded 0.0 points out of 1.0 possible points. 9. 9. ID: 25066824851 Which process is responsible for slowing the heart rate? A. Sympathetic excitation Incorrect B. Parasympathetic excitation Correct C. Bainbridge reflex D. Baroreceptor reflex The parasympathetic excitation slows the heart rate and is often referred to as the cardioinhibitory center. The sympathetic stimulation is often called the cardioexcitation center because the heart rate increases. The Bainbridge reflex causes the heart rate to increase after intravenous infusions of blood or fluid. The baroreceptor reflex facilitates blood pressure changes and heart rate changes. Awarded 0.0 points out of 1.0 possible points. 10.10. ID: 25066824856

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Which factors determine cardiac output? A. Parasympathetic and sympathetic activity B. Preload and afterload C. Heart rate and stroke volume Correct D. Right and left atrial pressure Cardiac output is directly related to the heart rate and stroke volume. Changes in either variable affect the cardiac output. Preload is the pressure generated in the left ventricle at the end of diastole (end- diastolic volume). Afterload is the resistance or impedance to the ejection of blood from the left ventricle. Although the parasympathetic stimulation has a bradycardic effect and sympathetic nervous system increases the frequency of the cardiac pacemaker and may influence cardiac output, these factors are not used in the cardiac output formula; neither are atrial pressures. Awarded 0.0 points out of 1.0 possible points. 11.11. ID: 25066824861 Which statement is true regarding the thoracic duct? A. The thoracic duct is the major source of venous return to the heart. B. The thoracic duct receives lymph from most of the body. Correct C. The thoracic duct receives lymph from the right arm, head, and thorax. D. Blood is dumped into the right atrium through the thoracic duct. Lymph is primarily water and small amounts of protein. It is reabsorbed through the lymph nodes and delivered to either the right lymphatic duct (lymph from right arm, head, and thorax) or the thoracic duct (rest of the body). These structures, in turn, dump the lymph into the inferior vena cava and superior vena cava (major sources of venous return to the heart), which conduct blood to the right atrium. Awarded 0.0 points out of 1.0 possible points. 12.12. ID: 25066824866 Which are the functions of the pericardial sac? (Select all that apply.) A. Prevents displacement of the heart during gravitational acceleration or deceleration Correct B. Physical barrier that protects the heart against infection and inflammation Correct C. Forms a lining that is continuous with the arteries, veins, and capillaries of the body D. Contains pain receptors and mechanoreceptors that affect blood pressure Correct

E. Creates a continuous closed circulatory system Functions of the pericardial sac are: (1) to prevent the displacement of the heart during gravitational acceleration or deceleration, (2) to provide a physical barrier that protects the heart against infection and inflammation from the lungs and pleural space, and (3) to provide pain receptors and mechanoreceptors that can elicit reflex changes in blood pressure and heart rate. The endocardium is the lining that is continuous with the arteries, veins, and capillaries of the body and creates a continuous closed circulatory system. Awarded 0.0 points out of 1.0 possible points.

EVOLVE CH 31

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