Correct Answer: A

Rationale: The correct answer is AV node. The AV node is responsible for delaying the impulse from the SA node, allowing the atria to contract before the ventricles. This delay ensures the effective pumping of blood in a coordinated manner. Choices B, C, and D are incorrect because the Bundle of His is responsible for transmitting the impulse to the Purkinje fibers, the SA node is the pacemaker of the heart responsible for initiating the heartbeat, and the aorta is the main artery carrying oxygenated blood from the heart to the body, respectively, none of which are involved in delaying the impulse to allow atrial contraction before ventricular contraction.

Correct Answer: C

Rationale: The correct answer is C: Tachycardia. Dobutamine is a medication that primarily increases heart rate (tachycardia) and blood pressure. Therefore, the adverse effects of dobutamine include tachycardia. Choices A, B, and D are incorrect. Heart failure is not an adverse effect of dobutamine; in fact, it is used to treat heart failure by increasing heart contractility. Bradycardia (slow heart rate) is not an expected adverse effect of dobutamine, as it usually increases heart rate. Respiratory distress is not a common adverse effect of dobutamine.

Correct Answer: A

Rationale: The correct answer is A: 'Anorexia can be a side effect of digoxin.' Anorexia, nausea, vomiting, and diarrhea are commonly known side effects of digoxin. Choice B, 'Tachycardia can be a side effect of digoxin,' is incorrect as digoxin is used to treat tachycardia, not cause it. Choice C, 'Constipation can be a side effect of digoxin,' is incorrect as constipation is not a typical side effect of digoxin. Choice D, 'Urinary retention can be a side effect of digoxin,' is also incorrect as urinary retention is not a common side effect associated with digoxin use.

Correct Answer: A

Rationale: A lobectomy is the correct answer. This surgical procedure involves removing one of the lobes of the lungs, commonly done to treat lung cancer or other serious lung ailments. Choice B, pneumonectomy, involves the complete removal of a lung, not just a lobe. Choice C, thoracotomy, is a surgical incision into the chest wall and is not specific to removing a lung lobe. Choice D, tracheostomy, is the creation of an opening in the windpipe to assist with breathing and is unrelated to lung lobe removal.

Correct Answer: A

Rationale: Cardiomyopathy is the correct answer. In cardiomyopathy, the heart muscle becomes weak and cannot pump blood effectively, which can lead to heart failure. Myocarditis (choice B) is inflammation of the heart muscle, not specifically causing muscle weakness. Endocarditis (choice C) is an infection of the inner lining of the heart chambers and valves. Pericarditis (choice D) is inflammation of the pericardium, the outer lining of the heart.