Correct Answer: A

Rationale: The correct answer is A: Skin. After the kidneys, the skin is the second largest route of water loss through perspiration. Choice B, Lungs, is incorrect as the lungs primarily exchange gases and do not play a significant role in water loss. Choice C, Intestines, is also incorrect as water loss through the intestines is minimal since most water is reabsorbed during digestion. Choice D, Muscles, is incorrect as muscles are not a major source of water loss in the body.

Correct Answer: D

Rationale: Dehydration can result from significant fluid loss due to vomiting, diarrhea, or inadequate fluid intake. Prolonged vomiting and diarrhea lead to excessive fluid loss from the body, contributing to dehydration. Similarly, not consuming enough fluids can also result in dehydration. Choice A and B are too specific as they only mention one cause each, while choice C is also correct but does not encompass all the potential causes of dehydration as mentioned in choice D.

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: C

Rationale: Inelastic skin is a normal change of aging. However, this does not mean that skin turgor cannot be assessed in older patients. Dehydration, not overhydration, causes inelastic skin with tenting. Overhydration, not dehydration, causes the skin to appear edematous and spongy. Choice A is incorrect because overhydration is not common among healthy older adults. Choice B is incorrect because dehydration leads to inelastic skin, not sponginess. Choice D is incorrect as skin turgor assessment can be done in patients of any age, including those over 70.

Correct Answer: B

Rationale: The correct answer is B, Interstitial fluid. Interstitial fluid is the fluid that surrounds and occupies the spaces between cells, providing them with nutrients and removing waste. Choices A, C, and D are incorrect because intracellular fluid refers to fluid inside cells, plasma refers to the liquid component of blood, and electrolyte refers to substances that dissociate into ions in solution, affecting fluid balance but not specifically found in spaces between cells.