ATI RN
ATI Fluid and Electrolytes
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: 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.
2. Under normal circumstances, the kidneys provide the greatest means of water loss. Which organ provides the second greatest means of water loss?
- A. Skin
- B. Lungs
- C. Intestines
- D. Muscles
Correct answer: A
Rationale: The correct answer is A: Skin. After the kidneys, the skin is the second largest route of water loss through perspiration. Choice B, Lungs, is incorrect as the lungs primarily exchange gases and do not play a significant role in water loss. Choice C, Intestines, is also incorrect as water loss through the intestines is minimal since most water is reabsorbed during digestion. Choice D, Muscles, is incorrect as muscles are not a major source of water loss in the body.
3. 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.
4. A nurse in the neurologic ICU has orders to infuse a hypertonic solution into a patient with increased intracranial pressure. This solution will increase the number of dissolved particles in the patient's blood, creating pressure for fluids in the tissues to shift into the capillaries and increase the blood volume. This process is best described as which of the following?
- A. Hydrostatic pressure
- B. Osmosis and osmolality
- C. Diffusion
- D. Active transport
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.
5. 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.
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