Correct Answer: D

Rationale: Intracellular to the extracellular fluid shift is not the cause of low blood pressure in this case. This fluid shift occurs when the cells lose water due to osmosis, such as in dehydration or hypernatremia. Interstitial to intravascular fluid shift is not the cause of low blood pressure in this case. This fluid shift occurs when the fluid moves from the tissue spaces to the blood vessels, such as in hypovolemia or hypotonic fluid administration. Interstitial to the intracellular fluid shift is not the cause of low blood pressure in this case. This fluid shift occurs when the fluid moves from the tissue spaces to the cells, such as in overhydration or hyponatremia. Intravascular to the interstitial fluid shift is the cause of low blood pressure in this case. This fluid shift occurs when the fluid moves from the blood vessels to the tissue spaces, such as in edema, inflammation, or increased capillary permeability. This reduces the blood volume and lowers the blood pressure.

Correct Answer: C

Rationale: This is incorrect because intracellular fluid is greater than extracellular fluid in a hypertonic state, not an isotonic state. A hypertonic state is when the solute concentration of the extracellular fluid is higher than the intracellular fluid, which causes water to move out of the cells and shrink them. This is incorrect because extracellular fluid is less than intracellular fluid in a hypotonic state, not an isotonic state. A hypotonic state is when the solute concentration of the extracellular fluid is lower than the intracellular fluid, which causes water to move into the cells and swell them. This is correct because intracellular and extracellular fluid is equal in an isotonic state. An isotonic state is when the solute concentration of the extracellular fluid is the same as the intracellular fluid, which causes no net movement of water across the cell membrane. This is incorrect because interstitial fluid is less than the transcellular fluid in a situation of fluid imbalance, not an isotonic state. Interstitial fluid is the fluid that surrounds the cells, while transcellular fluid is the fluid that is contained in specialized cavities, such as cerebrospinal fluid, synovial fluid, or pleural fluid.

Correct Answer: B

Rationale: Moist skin is not a sign of dehydration, but rather a sign of adequate hydration or sweating. Dehydration can cause dry skin, mucous membranes, and lips. Dark-colored urine is a sign of dehydration, as it indicates a high concentration of waste products and a low volume of water in the urine. Dehydration can cause the kidneys to conserve water and produce less urine. High blood pressure is not a sign of dehydration, but rather a sign of fluid overload or other factors such as stress, pain, or medication. Dehydration can cause low blood pressure, as it reduces the blood volume and the cardiac output. Distended neck veins are not a sign of dehydration, but rather a sign of fluid overload or right-sided heart failure. Dehydration can cause flat neck veins, as it reduces the venous return and the central venous pressure.

Correct Answer: D

Rationale: This is incorrect because the adrenal gland is not involved in the thirst mechanism. The adrenal gland is responsible for producing hormones such as cortisol, aldosterone, and adrenaline, which regulate stress response, blood pressure, and metabolism. This is incorrect because the cerebral cortex is not involved in the thirst mechanism. The cerebral cortex is the outer layer of the brain that is responsible for higher cognitive functions such as memory, language, and reasoning. This is incorrect because the pituitary gland is not directly involved in the thirst mechanism. The pituitary gland is a small gland at the base of the brain that produces hormones that control growth, reproduction, and metabolism. However, the pituitary gland does secrete antidiuretic hormone (ADH), which is regulated by the hypothalamus and affects water balance in the body. This is correct because the hypothalamus is the location of the thirst mechanism. The hypothalamus is a part of the brain that regulates many bodily functions such as temperature, appetite, sleep, and emotions. The hypothalamus also monitors the blood osmolarity and triggers the sensation of thirst when the blood is too concentrated.

Correct Answer: A

Rationale: This is correct because an isotonic solution has equal solute concentration on both sides of a semipermeable membrane, resulting in no net movement of water.