Question 1

Which of the following best describes the effect of antidiuretic hormone (ADH) on the kidneys?

Accepted Answer

ADH triggers the insertion of aquaporins in the distal tubule and collecting ducts, increasing water reabsorption.

Question 2

A patient presents with confusion, muscle weakness, and cardiac arrhythmias. Laboratory results show elevated potassium levels. Which of the following best explains the physiological consequence of this electrolyte imbalance?

Accepted Answer

Hyperkalemia makes the resting membrane potential of excitable cells more positive, impairing their ability to function.

Question 3

Which of the following equations represents the carbonic acid-bicarbonate buffer system in the blood?

Accepted Answer

$$ \mathrm{CO_2$ + H_2O \rightleftharpoons H_2CO_3 \rightleftharpoons $$HCO_3$$^- + H^+} $$

Question 4

A marathon runner collapses after the race. He is confused, his skin is dry, and his blood sodium is elevated. Which of the following best explains the sequence of events leading to his symptoms?

Accepted Answer

Profuse sweating without fluid replacement caused dehydration, increasing ECF osmolarity and drawing water out of cells.

Question 5

Which hormone is primarily responsible for increasing sodium reabsorption in the kidneys in response to low extracellular sodium concentration?

Accepted Answer

Aldosterone

Question 6

A patient with chronic obstructive pulmonary disease (COPD) is found to have a low blood pH and elevated $$ \mathrm{$$PCO_2$$} . $$Which acid-base disorder is most likely present?

Accepted Answer

Respiratory acidosis

Question 7

Which of the following best describes the movement of water between the plasma and interstitial fluid at the arteriolar end of a capillary?

Accepted Answer

High hydrostatic pressure pushes water out of the capillary into the interstitial fluid.

Question 8

Which of the following is a direct effect of aldosterone secretion?

Accepted Answer

Increased sodium reabsorption and increased potassium secretion in the kidneys

Question 9

A patient is given a large amount of intravenous isotonic saline. Which of the following best describes the expected effect on the patient’s fluid compartments?

Accepted Answer

ECF volume increases without a change in osmotic pressure; cell volume remains unchanged.

Question 10

Which of the following best explains why hypocalcemia increases neuronal excitability?

Accepted Answer

Low calcium increases sodium permeability of neurons, making them more likely to depolarize.

Question 11

Which of the following is the main source of metabolic acids in the body?

Accepted Answer

Carbon dioxide produced during glucose metabolism

Question 12

A patient with severe vomiting is at risk for which acid-base disturbance, and what is the primary compensatory response?

Accepted Answer

Metabolic alkalosis; compensation by hypoventilation

Question 13

Which of the following best describes the effect of atrial natriuretic peptide (ANP) on sodium and water balance?

Accepted Answer

ANP decreases sodium and water reabsorption, increasing urine output.

Question 14

Which of the following buffer systems is most important for resisting changes in blood pH?

Accepted Answer

Carbonic acid-bicarbonate buffer system

Question 15

A patient with diabetic ketoacidosis is hyperventilating. Which of the following best explains this compensatory response?

Accepted Answer

Hyperventilation decreases CO2, reducing H+ and raising blood pH.

Question 16

Which of the following best describes the effect of overhydration (hypotonic hydration) on cells?

Accepted Answer

Cells gain water and swell due to decreased ECF osmolarity.

Question 17

Which of the following is a direct effect of parathyroid hormone (PTH) when plasma calcium levels are low?

Accepted Answer

Increased calcium reabsorption in the kidneys and release from bone

Question 18

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

Accepted Answer

The amount of water and electrolytes gained must equal the amount lost.

Question 19

Which of the following best explains why a patient with severe diarrhea is at risk for metabolic acidosis?

Accepted Answer

Loss of bicarbonate ions in intestinal fluids reduces buffering capacity, increasing H+ concentration.

Question 20

Which of the following best describes the effect of a hypertonic extracellular fluid (ECF) on a cell?

Accepted Answer

Water moves out of the cell, causing it to shrink.

Fluid, Electrolyte, and Acid-Base Homeostasis: Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards