A patient with stable COPD receives prescriptions for an inhaled glucocorticoid and an inhaled beta2-adrenergic agonist. Which statement by the patient indicates understanding of this medication regimen?

Choice A reason: This is the correct mechanism of action of propranolol. Propranolol is a beta blocker medication, which means that it blocks the beta receptors in the heart and blood vessels. This reduces the sympathetic stimulation in cardiac muscle, which lowers the heart rate, contractility, and oxygen demand. This also reduces the renin release from the kidneys, which lowers the blood pressure.

Choice B reason: This is not the mechanism of action of propranolol. Propranolol does not increase the diuretic response in the renal tubules. This is the effect of diuretic medications, such as furosemide or hydrochlorothiazide, which increase the urine output and decrease the blood volume and pressure.

Choice C reason: This is not the mechanism of action of propranolol. Propranolol does not inhibit the conversion of angiotensin I to angiotensin II. This is the effect of angiotensin-converting enzyme (ACE) inhibitors, such as lisinopril or enalapril, which block the formation of angiotensin II, a potent vasoconstrictor that raises the blood pressure.

Choice D reason: This is not the mechanism of action of propranolol. Propranolol does not block alpha receptors throughout the body. This is the effect of alpha blockers, such as doxazosin or prazosin, which block the alpha receptors in the blood vessels and cause vasodilation, which lowers the blood pressure.

Choice A reason: Cardiac output has not fallen below normal levels. Cardiac output is the amount of blood pumped by the heart per minute. It is affected by the heart rate and the stroke volume. Angina pectoris does not directly affect the cardiac output, but it can reduce the stroke volume due to impaired ventricular filling.

Choice B reason: The vagus nerve is not stimulated. The vagus nerve is a cranial nerve that innervates the heart and other organs. It is part of the parasympathetic nervous system, which slows down the heart rate and lowers the blood pressure. Angina pectoris does not activate the vagus nerve, but it can trigger the sympathetic nervous system, which increases the heart rate and blood pressure.

Choice C reason: Myocardial stretch has not exceeded the upper limits. Myocardial stretch is the degree of tension or load on the cardiac muscle fibers. It is determined by the end-diastolic volume, which is the amount of blood in the ventricle at the end of relaxation. Angina pectoris does not cause excessive myocardial stretch, but it can impair the myocardial contractility due to ischemia.

Choice D reason: The myocardial oxygen supply has fallen below demand. This is the main cause of angina pectoris. It occurs when the coronary arteries, which supply blood and oxygen to the heart muscle, are narrowed or blocked by atherosclerosis or spasm. This creates an imbalance between the oxygen demand of the heart, which increases during exertion, and the oxygen supply, which is reduced by the obstruction.