ATI RN
ATI Fluid Electrolyte and Acid-Base Regulation
1. You are working on a burns unit, and one of your acutely ill patients is exhibiting signs and symptoms of third spacing. Based on this change in status, you should expect the patient to exhibit signs and symptoms of what imbalance?
- A. Metabolic alkalosis
- B. Hypermagnesemia
- C. Hypercalcemia
- D. Hypovolemia
Correct answer: D
Rationale: Third spacing refers to the loss of fluid from the intravascular space into the interstitial or third space, leading to a decrease in circulating blood volume. This condition results in hypovolemia, which is characterized by decreased blood volume. Metabolic alkalosis, hypermagnesemia, and hypercalcemia are not directly associated with third spacing. Metabolic alkalosis is an acid-base imbalance, hypermagnesemia is an excess of magnesium in the blood, and hypercalcemia is an excess of calcium in the blood, none of which are the primary concerns in cases of third spacing.
2. Which hormone reduces the amount of water in the body?
- A. ADH
- B. aldosterone
- C. ANH
- D. ADH and aldosterone
Correct answer: B
Rationale: The correct answer is 'aldosterone.' Aldosterone is the hormone that reduces the amount of water in the body by increasing the reabsorption of sodium and water from the kidney tubules. ANH (atrial natriuretic hormone) actually works to increase the excretion of sodium and water by the kidneys, leading to a reduction in blood volume and pressure. ADH (antidiuretic hormone) works to increase water reabsorption by the kidneys, thereby increasing blood volume. Therefore, choices A (ADH) and D (ADH and aldosterone) are incorrect in the context of reducing the amount of water in the body.
3. What happens first in dehydration?
- A. Intercellular fluid volume drops first.
- B. Plasma volume drops first.
- C. Interstitial fluid drops first.
- D. Neither interstitial nor intracellular fluid volume are affected.
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.
4. A nurse is taking care of a 65-year-old female patient in a medical-surgical unit who is in renal failure; during the assessment, the patient complains of tingling in her lips and fingers. When the nurse takes her blood pressure, she has a spasm in her wrist and hand. The nurse suspects:
- A. Hypophosphatemia
- B. Hypocalcemia
- C. Hypermagnesemia
- D. Hyperkalemia
Correct answer: B
Rationale: The patient's symptoms of tingling in the lips and fingers along with the wrist and hand spasm are indicative of tetany, a characteristic manifestation of hypocalcemia. Hypocalcemia and hypomagnesemia can present with sensations of tingling in the extremities and around the mouth. The spasm in the wrist and hand when taking blood pressure could be due to slight ischemia of the ulnar nerve, further supporting the suspicion of hypocalcemia in this patient. Hypophosphatemia, hypermagnesemia, and hyperkalemia do not typically present with these specific symptoms and manifestations.
5. Which positive ion is most prevalent in intracellular fluid?
- A. Calcium
- B. Potassium
- C. Sodium
- D. Magnesium
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.
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