ATI RN
ATI Fluid and Electrolytes
1. What is the most abundant positive ion in blood plasma?
- A. Potassium.
- B. Calcium.
- C. Sodium.
- D. Both potassium and sodium are in equal concentrations.
Correct answer: C
Rationale: The correct answer is C: Sodium. Sodium (Na+) is the most abundant cation in the extracellular fluid, including blood plasma. It plays a crucial role in maintaining fluid balance, nerve function, and is essential for various physiological processes. Choice A, Potassium, is also an important ion in the body but is predominantly found intracellularly. Choice B, Calcium, is an essential mineral in the body but is not the most abundant positive ion in blood plasma. Choice D is incorrect as sodium is the primary positive ion in blood plasma, with a much higher concentration compared to potassium.
2. Which negative ion is most important in intracellular fluid?
- A. Phosphate ions.
- B. Protein molecules.
- C. Chlorine.
- D. Phosphate ions and protein molecules.
Correct answer: D
Rationale: Intracellular fluid contains phosphate ions and protein molecules as essential anions. Phosphate ions play a crucial role in various cellular processes, including energy transfer. Proteins, being large molecules with negative charges, also contribute significantly to the negative ion concentration within cells. Chlorine is primarily an extracellular anion and is not as prominent as phosphate ions and proteins within intracellular fluid, making it a less important negative ion in this context. Therefore, the correct answer is D because both phosphate ions and protein molecules are crucial negative ions in intracellular fluid.
3. The nurse is admitting a patient with a suspected fluid imbalance. The most sensitive indicator of body fluid balance is:
- A. Daily weight
- B. Serum sodium levels
- C. Measured intake and output
- D. Blood pressure
Correct answer: A
Rationale: Daily weight is the most sensitive indicator of body fluid balance because it can show trends over time, helping in assessing the effectiveness of interventions and medications. While serum sodium levels provide objective data on electrolyte balance, they may not accurately reflect fluid balance, especially if a patient is dehydrated. Measured intake and output are crucial for assessing fluid balance, but it can be challenging to match the two due to various ways fluid is lost from the body. Blood pressure and other vital signs may not always be reliable indicators of fluid balance as they can be influenced by other factors beyond fluid status.
4. The healthcare provider is evaluating a patient's laboratory results. Based on the laboratory findings, what results will cause the release of an antidiuretic hormone (ADH)?
- A. Increased serum sodium
- B. Decreased serum sodium
- C. Decrease in serum osmolality
- D. Decrease in thirst
Correct answer: A
Rationale: The correct answer is A: Increased serum sodium. When serum sodium levels increase, it triggers the release of ADH by the posterior pituitary gland. ADH helps in retaining water, reducing urine output, and maintaining fluid balance. Choices B, C, and D are incorrect because decreased serum sodium, decrease in serum osmolality, and decrease in thirst do not stimulate the release of ADH.
5. A patient who is in renal failure partially loses the ability to regulate changes in pH because the kidneys:
- A. Regulate and reabsorb carbonic acid to change and maintain pH
- B. Buffer acids through electrolyte changes
- C. Regenerate and reabsorb bicarbonate to maintain a stable pH
- D. Combine carbonic acid and bicarbonate to maintain a stable pH
Correct answer: C
Rationale: The correct answer is C. In renal failure, the kidneys lose the ability to regulate pH by controlling bicarbonate levels in the extracellular fluid (ECF). The kidneys can regenerate and reabsorb bicarbonate ions to maintain a stable pH. Choices A, B, and D are incorrect because the kidneys do not primarily regulate or reabsorb carbonic acid, buffer acids through electrolyte changes, or combine carbonic acid and bicarbonate to maintain pH. The key function of the kidneys in maintaining pH balance lies in the control of bicarbonate levels.
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