Correct Answer: C

Rationale: This is a low value for serum calcium, which indicates hypocalcemia. Hypocalcemia can cause muscle spasms, tetany, seizures, and cardiac arrhythmias. This is also a low value for serum calcium, which indicates hypocalcemia. Hypocalcemia can cause muscle spasms, tetany, seizures, and cardiac arrhythmias. This is the normal range of serum calcium in adults. Calcium is essential for bone health, muscle contraction, nerve transmission, and blood clotting. This is a high value for serum calcium, which indicates hypercalcemia. Hypercalcemia can cause nausea, vomiting, constipation, confusion, lethargy, and kidney stones.

Correct Answer: D

Rationale: Kidney function is not indicated by the PaCO2 level, but rather by the creatinine and blood urea nitrogen (BUN) levels. The kidneys are responsible for regulating the HCO3- level, which is the other component of the carbonic acid-bicarbonate buffer system. Bicarbonate buffers are not indicated by the PaCO2 level, but rather by the HCO3- level. Bicarbonate buffers are substances that can accept or donate hydrogen ions to maintain the pH of the blood. They are part of the carbonic acid-bicarbonate buffer system, which is the main buffer system in the body. Phosphate buffers are not indicated by the PaCO2 level, but rather by the PO4^3^- level. Phosphate buffers are substances that can accept or donate hydrogen ions to maintain the pH of the intracellular fluid and the urine. They are part of the phosphoric acid-phosphate buffer system, which is the second most important buffer system in the body. Lung ventilation is indicated by the PaCO2 level, which is the partial pressure of carbon dioxide in the blood. Lung ventilation is the process of moving air in and out of the lungs, which affects the amount of carbon dioxide exhaled. The lungs are responsible for regulating the PaCO2 level, which is the other component of the carbonic acid-bicarbonate buffer system.

Correct Answer: A

Rationale: Narrow, peaked T waves are a sign of hyperkalemia, which is a high level of potassium in the blood. Potassium is an electrolyte that affects the electrical activity of the heart. Hyperkalemia can cause the T waves, which represent the repolarization of the ventricles, to become narrow and peaked, indicating a rapid and excessive repolarization. ST elevation is a sign of myocardial infarction, which is a heart attack. It indicates that the myocardium, or the heart muscle, is damaged and deprived of oxygen. ST elevation is not related to the potassium level, but rather to the coronary artery blood flow. Peaked P waves are a sign of atrial hypertrophy, which is an enlargement of the atria, the upper chambers of the heart. It indicates that the atria are under increased pressure or workload. Peaked P waves are not related to the potassium level, but rather to the atrial function. Prominent U waves are a sign of hypokalemia, which is a low level of potassium in the blood. Potassium is an electrolyte that affects the electrical activity of the heart. Hypokalemia can cause the U waves, which represent the repolarization of the Purkinje fibers, to become prominent and visible, indicating a delayed and prolonged repolarization.

Correct Answer: C

Rationale: One slice of wheat bread is not the best source of potassium, as it contains only about 70 mg of potassium per serving. The recommended daily intake of potassium for adults is 4,700 mg. One wedge of cantaloupe is a good source of potassium, as it contains about 430 mg of potassium per serving. However, it is not the best source of potassium among the choices given. One banana is the best source of potassium among the choices given, as it contains about 420 mg of potassium per serving. Bananas are also rich in fiber, vitamin C, and antioxidants. One slice of cheddar cheese is not the best source of potassium, as it contains only about 28 mg of potassium per serving. Cheese is also high in sodium, fat, and calories, which can have negative effects on blood pressure and cholesterol levels.

Correct Answer: A

Rationale: Renal failure can cause hyperkalemia because the kidneys are unable to excrete excess potassium from the body. This can lead to high levels of potassium in the blood, which can affect the heart and muscles. Diarrhea can cause hypokalemia, not hyperkalemia, because it can lead to loss of potassium from the gastrointestinal tract. This can result in low levels of potassium in the blood, which can also affect the heart and muscles. Blood transfusion can cause hyperkalemia if the blood is old or hemolyzed, meaning that the red blood cells have broken down and released potassium into the plasma. This can increase the potassium levels in the recipient's blood. Diaphoresis, or sweating, can cause hypokalemia, not hyperkalemia, because it can lead to loss of potassium from the skin. This can also lower the potassium levels in the blood.