Correct Answer: B

Rationale: The correct answer is B: Osmosis and osmolality. Osmosis is the movement of fluid from a region of low solute concentration to a region of high solute concentration across a semipermeable membrane. In this case, the hypertonic solution increases the number of dissolved particles in the blood, causing fluids to shift into the capillaries due to the osmotic pressure gradient. Osmolality refers to the concentration of solutes in a solution. Hydrostatic pressure refers to changes in water or volume related to water pressure, not the movement of fluids due to solute concentration differences. Diffusion is the movement of solutes from an area of greater concentration to lesser concentration; in an intact vascular system, solutes are unable to move freely, so diffusion does not play a significant role in this scenario. Active transport involves the movement of molecules against the concentration gradient with the use of energy, typically at the cellular level, and is not related to the vascular volume changes described in the question.

Correct Answer: D

Rationale: When a patient exhibits signs and symptoms of third-spacing, where fluid moves out of the intravascular space but not into the intracellular space, hypovolemia is expected. This leads to a decreased circulating blood volume. Increased calcium and magnesium levels are not typically associated with third-spacing fluid shift. Burns usually result in acidosis rather than alkalosis, making metabolic alkalosis an incorrect choice. Therefore, hypovolemia is the correct answer in this scenario.

Correct Answer: D

Rationale: Specific gravity is a test used to determine the concentration of solutes in the urine, reflecting the kidney's ability to concentrate urine. Changes in specific gravity can indicate fluid volume status, such as dehydration (fluid volume deficit) or overhydration (fluid volume excess). Options A, B, and C are incorrect as specific gravity does not directly detect nutritional deficits, hyperkalemia, or hypercalcemia.

Correct Answer: C

Rationale: The correct answer is C: hypernatremia. Hypernatremia refers to an elevated level of sodium in the blood, specifically when it is more than 145 mEq/L. Choice A, hyponatremia, is incorrect as it refers to low sodium levels. Choice B, hyperkalemia, is incorrect as it refers to high potassium levels, not sodium. Choice D, hypercalcemia, is also incorrect as it relates to elevated calcium levels, not sodium.

Correct Answer: D

Rationale: The correct answer is D. All the listed organs (lungs, skin, and intestines) contribute to fluid loss from the body. Lungs contribute to fluid loss through respiration, skin through sweating, and intestines through excretion. Therefore, none of the organs listed in the options retain fluids within the body. Choices A, B, and C are incorrect because all of these organs play a role in fluid output from the body.