Correct Answer: C

Rationale: In dehydration, the body first draws fluid from the interstitial space to maintain blood volume, leading to a decrease in interstitial fluid volume. This is why choice C is correct. Choice A is incorrect because intracellular fluid is not the first to be affected. Choice B is also incorrect as plasma volume reduction typically occurs after interstitial fluid loss. Choice D is incorrect as dehydration impacts both interstitial and intracellular fluid volumes.

Correct Answer: B

Rationale: When selecting a site for IV insertion on the hand or arm, it is important to consider the potential effects on the patient's mobility. The chosen site should not interfere with the patient's movement. Instructing the patient to hold his arm in a dependent position helps increase blood flow, aiding in vein visualization and insertion. It is advisable to choose a site with minimal hair if possible for better adhesion of the dressing. Removing the tourniquet after 2 minutes is recommended to prevent complications like hemoconcentration and potential vein damage. Therefore, option B is the correct choice as it aligns with best practices for IV insertion.

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: B

Rationale: The correct answer is interstitial fluid. Interstitial fluid is the fluid that surrounds and fills the spaces between cells, facilitating nutrient and waste exchange. Plasma, referred to in choice A, is the liquid part of blood. Choice C, intracellular fluid, is the fluid inside cells. Choice D, edema, is an abnormal accumulation of fluid in interstitial spaces, causing swelling.

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.