Question 1

Which of the following best explains why sodium (Na+) is the most important cation in the regulation of extracellular fluid (ECF) volume and water distribution?

Accepted Answer

Na+ is the only cation exerting significant osmotic pressure in the ECF, so water follows salt.

Question 2

A patient presents with confusion, muscle twitching, and convulsions after running a marathon and drinking excessive water without electrolyte replacement. Laboratory results show low plasma sodium. What is the most likely diagnosis?

Accepted Answer

Hypotonic hydration (water intoxication)

Question 3

Which equation correctly represents the dissociation of magnesium chloride (MgCl$$_2) in $$water?

Accepted Answer

$$\mathrm{$$MgCl_2$$ \rightarrow Mg$$^{2+}$$ + 2Cl^-}$$

Question 4

Which of the following is a consequence of dehydration at the cellular level?

Accepted Answer

Cells shrink due to water loss by osmosis.

Question 5

A patient with Addison’s disease is at risk for hypovolemia because they cannot produce enough aldosterone. What is the physiological consequence of this deficiency?

Accepted Answer

Increased sodium and water loss in urine

Question 6

Which buffer system is the most important for buffering pH changes in the extracellular fluid (ECF)?

Accepted Answer

Bicarbonate buffer system

Question 7

If a patient is experiencing metabolic acidosis, which compensatory mechanism would you expect to be activated?

Accepted Answer

Increased respiratory rate to blow off CO$$_2$$

Question 8

Which of the following best describes the movement of water between compartments when ECF osmolality increases?

Accepted Answer

Water moves from the ICF into the ECF

Question 9

A patient with chronic obstructive pulmonary disease (COPD) has a blood pH of 7.30, PCO$$_2 of 55 mm Hg$$, and elevated HCO$$_3^-. $$Which acid-base disorder and compensation are present?

Accepted Answer

Respiratory acidosis with renal compensation

Question 10

Which of the following is a direct effect of parathyroid hormone (PTH) on the kidneys?

Accepted Answer

Increases calcium reabsorption and decreases phosphate reabsorption

Question 11

Which of the following best explains why infants are more susceptible to dehydration and acidosis than adults?

Accepted Answer

Infants have a higher proportion of ECF, higher metabolic rate, and immature kidneys.

Question 12

Which of the following is true regarding the phosphate buffer system?

Accepted Answer

It is most effective in buffering urine and intracellular fluid.

Question 13

A patient with severe vomiting loses large amounts of stomach acid. What acid-base imbalance is most likely to develop?

Accepted Answer

Metabolic alkalosis

Question 14

Which of the following best describes the effect of aldosterone on renal tubules?

Accepted Answer

Increases Na+ reabsorption and K+ secretion

Question 15

Which of the following is a likely consequence of hypocalcemia?

Accepted Answer

Muscle tetany due to increased neuromuscular excitability

Question 16

Which of the following equations represents the reversible equilibrium for CO$$_2$$ buffering in blood?

Accepted Answer

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

Question 17

Which of the following is a primary mechanism by which the kidneys compensate for respiratory acidosis?

Accepted Answer

Reabsorbing more HCO$$_3^-$$ and secreting more H$$^+$$

Question 18

Which of the following is a characteristic of edema?

Accepted Answer

Atypical accumulation of interstitial fluid, causing tissue swelling

Question 19

Which of the following best describes the effect of hyperkalemia on cardiac muscle?

Accepted Answer

Hyperkalemia increases resting membrane potential, causing depolarization and reduced excitability.

Fluid, Electrolyte, and Acid-Base Balance: ANP Study Notes

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