Answer Key - Week 11 - Exercise 44-46 - Heart Structure, Cardiac Cycle, ECG

docx

School

CUNY College of Staten Island *

*We aren’t endorsed by this school

Course

BIO-150

Subject

Mechanical Engineering

Date

Jan 9, 2024

Type

docx

Pages

Uploaded by Rudddy03

Laboratory Exercise 44 Heart Structure Pre-Lab Answers 1. b 4. d 7. a 2. a 5. a 8. b 3. c 6. b 9. a Laboratory Assessments Answers Part A: Assessments Fig. 44.13 1. Brachiocephalic trunk 6. Left common carotid artery 2. Superior vena cava 7. Aortic arch 3. Ascending aorta 8. Pulmonary trunk 4. Right atrium 9. Left ventricle 5. Right ventricle 10. Apex of heart Fig. 44.14 1. Superior vena cava 6. Right ventricle 11. Apex of heart 2. Aorta 7. Interventricular septum 3. Right atrium 8. Left atrium 4. Aortic valve 9. Mitral valve 5. Tricuspid valve 10. Left ventricle Fig. 44.15 1. Aorta 6. Inferior vena cava 11. Pulmonary valve 2. Superior vena cava 7. Left pulmonary artery 12. Mitral valve 3. Aortic valve 8. Pulmonary trunk 13. Left ventricle 4. Right atrium 9. Left pulmonary veins 14. Right ventricle 5. Tricuspid valve 10. Left atrium Part B: Assessments Matching: 1. h 6. d 11. c 2. l 7. e 12. a 3. j 8. g 4. f 9. i 5. k 10. B Part C: Assessments 1. The left atrioventricular (mitral) valve has two cusps and attached chordae tendineae on the cusps. The aortic valve has three semilunar cusps and lacks any chordae tendinae attachments to the cusps. 2. The chordae tendineae and the papillary muscles prevent the cusps of the AV valves from swinging into the atria when the ventricles contract. 3. The thicker wall of the aorta allows it to withstand the higher pressure of the blood pumped out of the left ventricle. The thinner wall of the pulmonary trunk (artery) is related to the lower pressure of the blood that leaves the right ventricle. 4. Vena cava, right atrium, right AV (tricuspid) valve, right ventricle, pulmonary valve, pulmonary trunk, lungs, pulmonary vein, left atrium, left AV (mitral) valve, left ventricle, aortic valve, aorta. 5. The left ventricle chamber appears round, while the right ventricle chamber is somewhat curved around the left ventricle. 6. Answers will vary; answers will vary, but the right ventricle wall is thinner than the left ventricle wall. Critical Thinking Assessment: The thicker left ventricle wall contracts with a great force and pressure pumping blood into the extensive systemic circuit. The thinner right ventricle creates a somewhat lower pressure needed pumping blood into the pulmonary circuit.

Laboratory Exercise 45 Cardiac Cycle Pre-Lab Answers 1. a 4. c 7. a 2. d 5. a 8. b 3. b 6. b Laboratory Assessments Answers Part A: Assessments 1. Systole 5. Ventricles 2. Diastole 6. AV valves 3. Closed 7. Semilunar valves 4. Open 8. Murmur Part B: Assessments 1. (experimental results) 2. (experimental results) Part C: Assessments 1. SA 5. Atria 2. AV 6. Ventricles 3. Purkinje 7. Ventricles 4. Electrocardiogram 8. Atrial repolarization occurs at the same time as the ventricular fibers depolarize. The QRS complex obscures any recording of the atrial repolarization. Critical Thinking Assessment: Heart sounds; heart sounds are a mechanical functioning of the heart valves; thus, if the valves were stenotic or incompetent impairing their ability to open and close, then the heart sounds would be unusual. An ECG measures the electrical activity of the heart, which involves the depolarization and repolarization of the atrial and ventricular fibers of the myocardium. Part D: Assessments Fig. 45.7 1. SA node 5. Right bundle branch 9. Left bundle branch 2. Right atrium 6. Left atrium 10. Purkinje fibers 3. AV node 7. AV bundle 4. Right ventricle 8. Left ventricle Part E: Assessments 1. (experimental results) 2. Answers will vary. 3. Normal is 0.12-0.20 seconds. 4. The P-Q (P-R) interval indicates the time it takes for the atria to depolarize and the cardiac impulse to reach the AV node. 5. Because each QRS complex in an ECG pattern indicates a ventricular contraction, the heart rate can be determined by counting the QRS complexes that occur in one minute. 6. (experimental results) Critical Thinking Assessment: This person's heart rate is 72 beats per minute, and for each heart beat, there is one QRS complex. There are 60 seconds in one minute. Therefore, half of 72 beats per minute (which is 36) would indicated the number of QRS complexes that would have appeared on an ECG in the first 30 seconds. Critical Thinking Assessment: First; the QRS complex represents ventricular fibers depolarizing which leads to (causes) ventricular systole. When the ventricles are in systole, pressure builds within the chambers. Toward the end of the QRS complex, the entire ventricular myocardium has been depolarized. The pressure in the ventricles exceeds the pressure in the great arteries, so the ventricles are able to eject blood, which also pushes the AV valves closed (first "lubb" heart sound). During this time, the chordae tendineae are pulled taut by papillary muscles to prevent the valves from inverting; thus, allowing one-way flow out the ventricles to the great arteries. Second; the T wave represents the repolarization of the ventricular fibers which leads to (causes) ventricular relaxation (diastole). During diastole, pressure within the ventricles is much lower than the pressure in the great arteries; consequently, blood in the great arteries pushes against the semilunar valves, closing them and causing the second ("dupp") heart sound.

Laboratory Exercise 46 Electrocardiography: BIOPAC Exercise Laboratory Assessments Answers Part A: Data and Calculations Assessments 1. (experimental results) 2. (experimental results) 3a. (experimental results) 3b. (experimental results) Part B: Assessments 1. Yes. There was an increase in heart rate after getting up into the sitting position. While relaxing in the supine position, the heart rate is kept at its resting rate, due to parasympathetic control over the SA node. When a person rises from the supine position to a sitting position, there is a slight increase in the activity level. This results in an increase in sympathetic control over the SA node, and an increase in heart rate. 2. Yes. When a person is sitting at rest, there is parasympathetic control and the heart is at its resting rate. During and just after exercise, sympathetic control is dominant. This causes the heart rate to increase significantly to deliver oxygen and nutrients to active tissues, such as the heart and skeletal muscles. 3. There was a slight decrease in the duration of ventricular systole during exercise, which was still present at the beginning of the post-exercise period. Shortening the duration of systole is one way to increase the heart rate during exercise. If the duration of systole was shortened too much though, the heart rate would not be able to pump blood to the body efficiently. 4. There was a much more significant decrease in the duration of ventricular diastole in Segment 4 (post-exercise), compared to the change in systole. Shortening the relaxation period of the ventricles can greatly increase the heart rate during exercise. Since most of the ventricular filling occurs in the early stage of diastole, shortening the duration of diastole does not affect the filling of the ventricles very much. 5. The heart rate increased slightly during inhalation, and decreased slightly during exhalation. The sympathetic nervous system is dominant during inhalation, resulting in the increase in heart rate. The parasympathetic nervous system dominates during exhalation, which causes the heart rate to decrease.

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version