Fluid and Electrolyte Balance 2 Flashcards
6 cards from real CRNI practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Fluid and Electrolyte Balance 2 flashcards as text
Which electrolyte is the primary determinant of extracellular fluid osmolality?
Answer: Sodium
Sodium is the dominant cation in extracellular fluid and accounts for approximately 90% of extracellular osmolality, making it the principal regulator of ECF volume and tonicity.
Antidiuretic hormone (ADH) is released in response to which of the following stimuli?
Answer: Increased serum osmolality
ADH is secreted by the posterior pituitary when osmoreceptors detect a rise in plasma osmolality. ADH promotes water reabsorption in the renal collecting ducts to dilute the plasma and restore normal osmolality.
A patient has a serum potassium of 2.8 mEq/L. Which clinical finding would the nurse most expect to assess?
Answer: Muscle weakness and fatigue
Hypokalemia (serum K⁺ < 3.5 mEq/L) impairs neuromuscular conduction, leading to skeletal muscle weakness and fatigue. Peaked T waves and bradycardia are associated with hyperkalemia, not hypokalemia.
Which fluid compartment contains the largest proportion of total body water in an adult?
Answer: Intracellular fluid
Intracellular fluid (ICF) accounts for approximately 40% of body weight, or about two-thirds of total body water — far exceeding any other single compartment. Extracellular fluid (interstitial + intravascular) makes up the remaining one-third.
Which mechanism describes the movement of water across a semi-permeable membrane from an area of lower solute concentration to an area of higher solute concentration?
Answer: Osmosis
Osmosis is the passive movement of water across a semi-permeable membrane down its own concentration gradient — from a region of lower solute (higher water) concentration to higher solute (lower water) concentration — until equilibrium is reached.
A patient receiving rapid, large-volume infusion of 0.9% normal saline is at greatest risk for which electrolyte imbalance?
Answer: Hyperchloremic metabolic acidosis
Normal saline contains 154 mEq/L of chloride, which exceeds plasma chloride levels (~103 mEq/L). Large infusions deliver excess chloride, suppressing bicarbonate reabsorption and producing a dilutional hyperchloremic metabolic acidosis.