NURS231/ NURS 231 Exam 3: (Latest 2026/ 2027 Update) Pathophysiology: Fluid and Electrolyte Balance, Acid-Base Disorders, and Hematology Review| Practice Questions with Verified Answers and Detailed Rationales| Grade A| 100% Correct (Verified Solutions)

INSTANT PDF DOWNLOAD — This comprehensive practice test for NURS 231 Exam 3 at Portage Learning covers Pathophysiology for the 2026/2027 academic year third examination. It features practice questions with verified answers and detailed rationales in multiple-choice, select-all-that-apply, true/false, and short answer formats aligned with the Portage Learning nursing curriculum. FLUID AND ELECTROLYTE BALANCE (EXAM 3 FOCUS) Fundamental Concepts Question 1: Body Fluid Compartments Which statement correctly describes the distribution of body fluids in a healthy adult? A) Intracellular fluid (ICF) accounts for approximately one-third of total body water B) Extracellular fluid (ECF) is subdivided into interstitial fluid and plasma C) The majority of body water is located in the extracellular compartment D) Transcellular fluid includes cerebrospinal fluid, synovial fluid, and peritoneal fluid Correct Answer: B, D Rationale: In a healthy adult, total body water (TBW) is distributed as follows: Intracellular fluid (ICF) accounts for approximately two-thirds (about 65-75%) of TBW, not one-third. Extracellular fluid (ECF) accounts for approximately one-third of TBW and is subdivided into: interstitial fluid (fluid between cells, about 75% of ECF), plasma (fluid within blood vessels, about 25% of ECF), and transcellular fluid (cerebrospinal fluid, synovial fluid, peritoneal fluid, pleural fluid, intraocular fluid, digestive secretions). Transcellular fluid is a small fraction of ECF (about 1-3%). Both statements B and D are correct. NGN Item Type: Select-All-That-Apply (SATA) Question 2: Osmosis and Tonicity A patient receives an intravenous infusion of 0.45% sodium chloride (half-normal saline). This solution is considered: A) Isotonic – will not cause fluid shifts between compartments B) Hypertonic – will draw fluid from the intracellular space into the intravascular space C) Hypotonic – will cause fluid to move from the intravascular space into the intracellular space D) Hypertonic – will cause cells to shrink Correct Answer: C Rationale: 0.45% sodium chloride (half-normal saline) is a hypotonic solution relative to plasma. It has a lower osmolality than extracellular fluid. Therefore, water moves by osmosis from the intravascular space (higher water concentration) into the interstitial space and then into the intracellular space (lower water concentration). This causes cells to swell. Isotonic solutions (e.g., 0.9% normal saline, lactated Ringer's) do not cause fluid shifts. Hypertonic solutions (e.g., 3% saline, D10W) draw fluid out of cells, causing them to shrink. Hypotonic solutions are used to treat cellular dehydration (e.g., hypernatremia). Portage Learning Alignment: Understanding tonicity is essential for safe IV fluid administration and management of electrolyte disorders. Electrolyte Imbalances – Sodium Question 3: Hyponatremia A patient presents with nausea, headache, confusion, and muscle cramps. Laboratory results show serum sodium of 128 mEq/L (normal 135-145). The nurse practitioner recognizes that this patient is at risk for which severe complication? A) Cardiac arrhythmias due to hypokalemia B) Cerebral edema and seizures C) Metabolic alkalosis D) Hypervolemia and pulmonary edema Correct Answer: B Rationale: Hyponatremia (low serum sodium) creates an osmotic gradient that causes water to shift from the intravascular space into the intracellular space. In the brain, this leads to cerebral edema (swelling of brain cells). Severe or acute hyponatremia can cause headache, confusion, seizures, coma, and respiratory arrest due to brainstem herniation. Rapid correction of chronic hyponatremia is dangerous due to risk of osmotic demyelination syndrome (central pontine myelinolysis). Treatment depends on volume status and symptoms; severe symptomatic hyponatremia may require hypertonic saline (3% NaCl). Portage Learning Alignment: Hyponatremia is the most common electrolyte disorder in hospitalized patients and can be life-threatening if not recognized. Question 4: Hypernatremia A patient has a serum sodium level of 155 mEq/L. Which clinical finding would the nurse practitioner expect? A) Dry mucous membranes and decreased skin turgor