ATI Fluid and Electrolytes

Correct Answer: D

Rationale: The correct answer is D, ADH (Antidiuretic hormone). ADH is produced by the pituitary gland and functions to increase water reabsorption in the kidneys. Choices A, B, and C are incorrect as they do not refer to a hormone responsible for increasing water absorption in the kidney.

Correct Answer: C

Rationale: The correct answer is C: increased aldosterone secretion. Aldosterone, a hormone produced by the adrenal glands, increases sodium reabsorption in the kidneys, leading to retention of sodium and water in the interstitial fluid. Increased aldosterone secretion enhances the reabsorption of sodium, thereby increasing its retention. Choice A is incorrect because decreased aldosterone secretion would lead to less sodium reabsorption and increased excretion. Choice B is incorrect because increased ADH secretion primarily affects water reabsorption rather than sodium. Choice D is incorrect because decreased ADH secretion would lead to increased water excretion but not necessarily affect sodium retention.

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: 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 Potassium (K+). Potassium is the predominant cation found within cells, making it the most prevalent positive ion in intracellular fluid. Calcium, sodium, and magnesium are also essential ions in the body, but they are not as abundant in intracellular fluid. Calcium is vital for bone health and muscle function, sodium helps in maintaining fluid balance and nerve function, and magnesium is involved in numerous biochemical reactions.