Question 1

Which of the following best describes the principle of mass balance as it applies to fluid and electrolyte homeostasis in the human body?

Accepted Answer

The amount of water and electrolytes gained by the body must equal the amount lost to maintain homeostasis.

Question 2

A patient is given an intravenous (IV) solution that is hypertonic compared to their cytosol. What is the most likely effect on their red blood cells?

Accepted Answer

Water will move out of the cells, causing them to shrink (crenate).

Question 3

Which hormone is primarily responsible for increasing water reabsorption in the kidneys by inserting aquaporins into the distal tubule and collecting duct membranes?

Accepted Answer

Antidiuretic hormone (ADH)

Question 4

A patient presents with muscle weakness, mental status changes, and a slowed heart rate after taking diuretics. Laboratory results show a plasma potassium ion concentration of 3.2 mEq/L. What is the most likely diagnosis?

Accepted Answer

Hypokalemia

Question 5

Which of the following best explains why overhydration (hypotonic hydration) can lead to cerebral edema and potentially fatal complications?

Accepted Answer

Water moves into neurons due to a hypotonic extracellular fluid, causing them to swell.

Question 6

Which buffer system is most important for resisting changes in pH in the cytosol and in the filtrate within the kidney tubule?

Accepted Answer

Phosphate buffer system

Question 7

A patient with chronic obstructive pulmonary disease (COPD) has a blood pH of 7.30 and elevated arterial $$\mathrm{CO_2$}$$ levels. Which acid-base disorder is most likely present?

Accepted Answer

Respiratory acidosis

Question 8

Which of the following is a direct effect of parathyroid hormone (PTH) on calcium and phosphate homeostasis?

Accepted Answer

Increases osteoclast activity, raising blood calcium and decreasing phosphate reabsorption in the kidney.

Question 9

A patient is experiencing prolonged vomiting and is found to have an elevated blood pH and high bicarbonate ion concentration. Which compensatory response would you expect to see?

Accepted Answer

Hypoventilation to retain $$\mathrm{CO_2$}$$ and increase hydrogen ion concentration.

Question 10

Which of the following best describes the effect of aldosterone on electrolyte balance in the distal tubule of the nephron?

Accepted Answer

Increases sodium reabsorption and potassium secretion.

Question 11

A patient with severe diarrhea is at risk for which acid-base disturbance, and what is the primary mechanism?

Accepted Answer

Metabolic acidosis due to loss of bicarbonate ions from the gastrointestinal tract.

Question 12

Which of the following statements about the distribution of water in the body is correct?

Accepted Answer

About 60% of total body water is found inside cells as cytosol (intracellular fluid).

Question 13

Which of the following best explains why a person with normal sodium ion content but decreased total body water will develop hypernatremia?

Accepted Answer

The concentration of sodium ions increases as the number of water molecules decreases.

Question 14

Which of the following is a function of chloride ions in the body?

Accepted Answer

They are involved in the production of hydrochloric acid in the stomach.

Question 15

A patient with renal failure is unable to excrete fixed acids efficiently. What acid-base disturbance is most likely to develop?

Accepted Answer

Metabolic acidosis

Question 16

Which of the following best describes the role of the carbonic acid–bicarbonate buffer system in the blood?

Accepted Answer

It minimizes changes in pH by binding or releasing hydrogen ions as needed.

Question 17

A patient with a plasma calcium ion concentration of 11.2 mg/dL is most likely to experience which of the following symptoms?

Accepted Answer

Mental sluggishness and weak muscle activity

Question 18

Which of the following is a direct effect of antidiuretic hormone (ADH) on the kidneys?

Accepted Answer

Increases water reabsorption by inserting aquaporins into the collecting duct.

Question 19

A patient is found to have a blood pH of 7.48, low arterial $$\mathrm{CO_2$}$$, and low bicarbonate ion concentration. Which acid-base disorder and compensation are present?

Accepted Answer

Respiratory alkalosis with partial renal compensation

Fluid, Electrolyte, and Acid-Base Homeostasis: ANP College Study Guide

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