Correct Answer: A

Rationale: The correct answer is Parathyroid hormone (Choice A). Parathyroid hormone plays a key role in regulating calcium levels in the blood. When there is an imbalance in parathyroid hormone secretion, it can lead to increased calcium levels in the blood. Antidiuretic hormone (Choice B) is involved in regulating water balance, not calcium levels. Calcitonin (Choice C) helps lower blood calcium levels and is unlikely to cause an increase. Melatonin (Choice D) regulates sleep-wake cycles and does not have a direct effect on calcium levels in the blood.

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: Contact dermatitis is typically caused by contact with a skin allergen that triggers an allergic reaction. Choice A, fungal infection, is incorrect as contact dermatitis is not caused by fungi. Choice B, long-term disorder from gout, is also incorrect as gout is not typically associated with contact dermatitis. Choice D, Staphylococcal infection, is incorrect as contact dermatitis is primarily an allergic reaction rather than a bacterial infection.

Correct Answer: D

Rationale: The sinoatrial node (SA node) in the atrium is indeed responsible for initiating the electrical impulse that starts the heart's rhythm. The SA node is known as the heart's natural pacemaker. Choices A, B, and C are incorrect because while the Purkinje fibers, bundle branches, and atrioventricular node play crucial roles in the conduction of the electrical impulse throughout the heart, the SA node is specifically responsible for initiating this impulse.

Correct Answer: B

Rationale: Aldosterone functions by causing the retention of sodium in the body, which results in an increase in fluid volume and blood pressure. Choice A is incorrect because aldosterone actually promotes sodium retention rather than release. Choice C is incorrect as it states that aldosterone decreases fluid volume, which is not accurate. Choice D is incorrect because aldosterone does not enhance intracellular sodium production; instead, it primarily acts on sodium reabsorption in the kidneys.