Correct Answer: A

Rationale: When administering furosemide (Lasix), it is crucial to monitor potassium levels closely. Furosemide is a loop diuretic that can lead to potassium loss, potentially causing hypokalemia. Monitoring potassium levels helps prevent adverse effects associated with low potassium, such as cardiac arrhythmias. While monitoring sodium, calcium, and chloride levels may also be important in certain situations, potassium is the most critical to monitor when administering furosemide.

Correct Answer: A

Rationale: The correct answer is A, Myocarditis. Myocarditis is an inflammation of the heart muscle, typically caused by a viral infection. It can impair the heart's ability to pump blood efficiently, potentially leading to other complications. Endocarditis (choice B) is an inflammation of the inner lining of the heart chambers and valves. Pericarditis (choice C) is inflammation of the pericardium, the outer lining of the heart. Cardiomyopathy (choice D) is a disease of the heart muscle that affects the heart's ability to pump blood.

Correct Answer: A

Rationale: The PR interval measures the time it takes for the electrical impulse to travel from the atria to the ventricles. It is crucial in diagnosing heart rhythm disorders, as abnormalities in this interval can indicate conduction abnormalities between the atria and ventricles. Choices B, C, and D are incorrect. The QRS complex represents ventricular depolarization, the QT interval represents the duration of ventricular repolarization, and the ST segment represents the time between ventricular depolarization and repolarization.

Correct Answer: A

Rationale: The correct answer is A, the carotid body. The carotid body is the major chemoreceptor of the heart responsible for detecting changes in blood oxygen, carbon dioxide, and pH levels. This specialized structure helps regulate the cardiovascular system's response to maintain appropriate oxygen levels in the blood. Choices B, C, and D are incorrect as they are not directly involved in chemoreception in the heart. The aortic body is primarily involved in blood pressure regulation, the vagus nerve is a cranial nerve responsible for parasympathetic innervation, and the SA node is known as the heart's natural pacemaker.

Correct Answer: A

Rationale: Pulmonary hypertension is a condition characterized by the thickening and stiffening of the arteries in the lungs, resulting in elevated blood pressure in the pulmonary arteries. This condition is distinct from the other choices provided. Pulmonary fibrosis involves scarring of lung tissue, pulmonary embolism is a blockage in the pulmonary artery, and pulmonary edema is the accumulation of fluid in the lungs.