What is the primary cause of angina?

Correct Answer: B

Rationale: The correct answer is B: Obstruction of the coronary arteries. Angina is primarily caused by a reduced blood flow to the heart due to blockages or narrowing in the coronary arteries. Choice A is incorrect because while increased oxygen demand can contribute to angina symptoms, it is not the primary cause. Choice C is incorrect as angina is not caused by a lack of oxygen in the lungs. Choice D is also incorrect as angina is not related to decreased blood supply to the liver.

Correct Answer: A

Rationale: The correct answer is A: Erythropoietin. The kidneys produce erythropoietin to stimulate the production of red blood cells. Insulin and glycogen are not hormones secreted by the kidneys; insulin is produced by the pancreas, and glycogen is a stored form of glucose. Testosterone is a hormone primarily produced by the testes in males and to a lesser extent in females. Thyroid stimulating hormone is produced by the pituitary gland to regulate thyroid function, not red blood cell production.

Correct Answer: B

Rationale: A pulmonary embolism is commonly caused by a blood clot that originates in the venous system of the lower extremity and travels to the lungs, blocking blood flow. This clot is known as a venous thromboembolism. An autoimmune disorder (Choice A) is not typically associated with pulmonary embolism. Intracranial pressure (Choice C) refers to pressure inside the skull and is unrelated to pulmonary embolism. Hypotension (Choice D) is low blood pressure and is not a common cause of pulmonary embolism.

Correct Answer: A

Rationale: Renin is the correct answer. When arterial blood pressure decreases, the kidneys release renin, which triggers a series of reactions ultimately leading to an increase in blood pressure and peripheral resistance. Antidiuretic hormone (choice B) is involved in water retention, atrial natriuretic hormone (choice C) promotes sodium excretion and lowers blood pressure, and insulin (choice D) regulates glucose metabolism, not blood pressure.

Correct Answer: A

Rationale: The correct answer is A: Respiratory acidosis. In respiratory acidosis, there is an accumulation of CO2 in the blood, leading to a decrease in pH. The elevated PaCO2 of 55 mmHg in the given results indicates hypoventilation, causing respiratory acidosis. Choices B, C, and D are incorrect because the provided data does not show metabolic acidosis, respiratory alkalosis, or metabolic alkalosis.