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: 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: Tachycardia. Tachycardia, which is an increased heart rate, is a classic clinical manifestation of hyperthyroidism. In hyperthyroidism, there is an excess production of thyroid hormones, leading to an increased metabolic rate. This increased metabolism can cause symptoms such as a rapid heart rate. Choices B, C, and D are incorrect because constipation, weight gain, and fatigue are more commonly associated with hypothyroidism, where there is a deficiency of thyroid hormones leading to a slower metabolic rate.

Correct Answer: B

Rationale: The correct answer is B: Red blood cells. Hematopoiesis is the process of blood cell formation that primarily occurs in the bone marrow. Red blood cells are one of the main cell types formed during this process. Pancreatic beta cells (Choice A), gastric parietal cells (Choice C), and neurons and glial cells (Choice D) are not formed during hematopoiesis. Pancreatic beta cells are involved in insulin production, gastric parietal cells secrete gastric acid, and neurons and glial cells are part of the nervous system.

Correct Answer: C

Rationale: The correct answer is C: Increased secretion of antidiuretic hormone (ADH). Syndrome of inappropriate antidiuretic hormone (SIADH) is characterized by the excessive release of ADH, which leads to water retention and dilution of blood sodium levels. Choices A, B, and D are incorrect because SIADH is not associated with decreased insulin production, decreased ADH production, or increased production of insulin.