Correct Answer: C

Rationale: The correct answer is C: Protein in the blood plasma. Plasma proteins, especially albumin, create oncotic pressure, which is the main force responsible for holding water within the blood capillaries. Capillary blood pressure (Choice A) is involved in pushing blood through the capillaries, while sodium and chloride in the blood plasma (Choices B and D) are electrolytes and do not play a significant role in the water-holding force within capillaries.

Correct Answer: A

Rationale: The correct answer is A: Kidneys. The kidneys play a crucial role in regulating the amount of sodium in the body. They achieve this by filtering blood and controlling the excretion or reabsorption of sodium. The small intestine is primarily responsible for nutrient absorption, not sodium regulation. The large intestine is mainly involved in water absorption and waste elimination, not sodium balance. The skin helps regulate body temperature through sweating and does not directly regulate sodium levels.

Correct Answer: A

Rationale: Corrected Rationale: To assess a patient's magnesium status, the nurse should check deep tendon reflexes. Diminished deep tendon reflexes may indicate high serum magnesium levels, as hypermagnesemia can lead to neuromuscular effects. Tachycardia, cool clammy skin, and acute flank pain are not typically associated with high magnesium levels and are not priority assessments in this situation.

Correct Answer: B

Rationale: The symptoms described, including tingling in the lips and fingers, intermittent spasms, and increased muscle tone, are indicative of tetany, which is a common manifestation of hypocalcemia. Hypocalcemia can lead to neuromuscular irritability, causing symptoms such as paresthesias and muscle spasms. Hypophosphatemia primarily affects the central nervous system, resulting in seizures and coma. Hypermagnesemia typically presents with hypoactive reflexes and somnolence. Hyperkalemia can cause paresthesias and anxiety, but in this case, the patient's symptoms are more suggestive of hypocalcemia.

Correct Answer: D

Rationale: The correct answer is D, ADH and aldosterone. Both antidiuretic hormone (ADH) and aldosterone increase water retention by the kidneys, thereby increasing blood volume. ADH acts on the kidneys to increase water reabsorption, while aldosterone acts on the kidneys to promote sodium reabsorption, leading to water retention. Choice A, ADH, is partially correct as it alone increases water retention. Choice B, aldosterone, is also partially correct as it alone increases water retention. Choice C, ANH (atrial natriuretic hormone), actually decreases water retention by promoting sodium excretion and inhibiting aldosterone release.