Correct Answer: A

Rationale: This is correct because 3.5 to 5.0 mEq/L is the normal range of serum potassium level in adults. Potassium is an electrolyte that is important for nerve and muscle function, as well as acid-base balance. This is incorrect because 8.5 to 10.5 mg/dL is the normal range of serum calcium level in adults, not potassium. Calcium is an electrolyte that is involved in bone health, muscle contraction, and blood clotting. This is incorrect because 135 to 145 mEq/L is the normal range of serum sodium level in adults, not potassium. Sodium is an electrolyte that is essential for fluid balance, nerve transmission, and muscle contraction. This is incorrect because 1.8 to 2.6 mEq/L is the normal range of serum magnesium level in adults, not potassium. Magnesium is an electrolyte that is important for muscle and nerve function, as well as enzyme activity.

Correct Answer: B

Rationale: Potassium (K+) imbalance can cause cardiac and neuromuscular symptoms, such as arrhythmias, palpitations, muscle weakness, or paralysis, but not abdominal pain, urinary retention, or confusion.

Correct Answer: D

Rationale: Producing phosphate buffers is not the main function of the kidneys in response to acid-base disturbances. Phosphate buffers are mainly found in the intracellular fluid and the urine, where they help to maintain the pH by binding or releasing hydrogen ions. Adjusting PaCO2 levels is not the function of the kidneys, but rather the function of the lungs in response to acid-base disturbances. The lungs regulate the PaCO2 levels by increasing or decreasing the rate and depth of respiration, which affects the amount of carbon dioxide exhaled. Producing protein buffers is not the function of the kidneys, but rather the function of the cells and the plasma in response to acid-base disturbances. Protein buffers are the most abundant and versatile buffers in the body, as they can act as acids or bases by donating or accepting hydrogen ions. Excreting or reabsorbing hydrogen or bicarbonate is the main function of the kidneys in response to acid-base disturbances. The kidneys regulate the HCO3- levels by either reabsorbing it from the filtrate or generating it from carbon dioxide and water. The kidneys also regulate the hydrogen ion levels by either excreting it into the urine or exchanging it for sodium ions.

Correct Answer: B

Rationale: This is incorrect because 120 to 140 mEq/L is a low range for serum sodium, which indicates hyponatremia. Hyponatremia can cause confusion, lethargy, seizures, and coma. This is correct because 135 to 145 mEq/L is the normal range of serum sodium in adults. Sodium is essential for fluid balance, nerve transmission, and muscle contraction. This is incorrect because 150 to 160 mEq/L is a high range for serum sodium, which indicates hypernatremia. Hypernatremia can cause thirst, dry mouth, agitation, and convulsions. This is incorrect because 165 to 175 mEq/L is a very high range for serum sodium, which indicates severe hypernatremia. Severe hypernatremia can cause irreversible brain damage and death.

Correct Answer: A

Rationale: This is correct because acidosis is a condition where the serum pH is lower than the normal range of 7.35 to 7.45. Acidosis can be caused by an excess of acids or a loss of bases in the body, which can affect the function of various organs and systems. This is incorrect because equal bicarbonate is not a condition, but a term that describes the balance between bicarbonate (HCO3-) and carbonic acid (H2CO3) in the blood. Bicarbonate is a base that buffers the acids in the blood and maintains the pH. Equal bicarbonate means that the ratio of bicarbonate to carbonic acid is 20:1, which is the normal value. This is incorrect because neutral carbonic acid is not a condition, but a term that describes the pH of carbonic acid (H2CO3) in the blood. Carbonic acid is an acid that forms when carbon dioxide (CO2) dissolves in water. Neutral carbonic acid means that the pH of carbonic acid is 7.0, which is neither acidic nor basic. This is incorrect because alkalosis is a condition where the serum pH is higher than the normal range of 7.35 to 7.45. Alkalosis can be caused by a loss of acids or an excess of bases in the body, which can affect the function of various organs and systems.