Nurs601 ADVANCED PATHOPHYSIOLOGY Quiz 4

1. Which statement made by a student indicates the healthcare professional needs to describe the pericardium again? a. The pericardium is a double-walled membranous sac that encloses the heart. b. It is made up of connective tissue and a surface layer of squamous cells. c. The pericardium protects the heart against infection and inflammation from the lungs and pleural space. d. It contains pain and mechanoreceptors that can elicit reflex changes in blood pressure and heart rate. - ANS: B The pericardium is made up of a surface layer of mesothelium over a thin layer of connective tissue. The healthcare professional would need to re-explain if the student stated the pericardium is made up of connective tissue and a layer of squamous cells. The other statements are accurate. 1. Which cardiac chambers have the thinnest wall and why? a. The right and left atria; they are low-pressure chambers that serve as storage units and conduits for blood. b. The right and left atria; they are not directly involved in the preload, contractility, or afterload of the heart. c. The left ventricle; the mean pressure of blood coming into this ventricle is from the lung, which has a low pressure. d. The right ventricle; it pumps blood into the pulmonary capillaries, which have a lower pressure compared with the systemic circulation. - ANS: A The two atria have the thinnest walls because they are low-pressure chambers that serve as storage units and conduits for blood that is emptied into the ventricles. The ventricles have thicker walls in order to pump blood against resistance. 1. Which chamber of the heart endures the highest pressures? a. Right atrium b. Left atrium c. Left ventricle d. Right ventricle - ANS: C Pressure is greatest in the left ventricle with a systolic range of 90 to 140 mmHg. The right ventricle is next with a systolic range of 15 to 28 mmHg, followed by the left and right atria, respectively. 1. What is the process that ensures mitral and tricuspid valve closure after the ventricles are filled with blood? a. Chordae tendineae relax, which allows the valves to close. b. Increased pressure in the ventricles pushes the valves to close. c. Trabeculae carneae contract, which pulls the valves closed. d. Reduced pressure in the atria creates a negative pressure that pulls the valves closed. - ANS: B During ventricular relaxation, the two atrioventricular valves open and blood flows from the higher pressure atria to the relaxed ventricles. With increasing ventricular pressure, these valves close and prevent backflow into the atria as the ventricles contract. The chordae tendineae attach the bottom end of the AV valves to the papillary muscles. The endocardium covers beamlike projections of muscle tissue, called trabeculae carneae. The valves are not pulled closed by reduced atrial pressure. 1. A student asks the healthcare professional to explain the function of the papillary muscles. What response by the professional is best? a. The papillary muscles close the semilunar valves. b. These muscles prevent backward expulsion of the atrioventricular valves. c. They open the atrioventricular valves. d. The papillary muscles open the semilunar valves. - ANS: B The papillary muscles are extensions of the myocardium that pull the cusps of the AV valves together and downward at the onset of ventricular contraction, thus preventing their backward expulsion into the atria. They do not close the semilunar valves or open the AV valves or semilunar valves. 1. During the cardiac cycle, why do the aortic and pulmonic valves close after the ventricles relax? a. Papillary muscles relax, which allows the valves to close. b. Chordae tendineae contract, which pulls the valves closed. c. Reduced pressure in the ventricles creates a negative pressure, which pulls the valves closed. d. Blood fills the cusps of the valves and causes the edges to merge, closing the valves. - ANS: D When the ventricles relax, blood fills the cusps and causes their free edges to meet