Acid-Base & Water Balance — Multiple Choice Questions

Acid-Base & Water Balance — Multiple Choice Questions

1. Which fluid compartment contains the majority of body water?

A. Plasma

B. Extracellular fluid (ECF)

C. Intracellular fluid (ICF)

D. Interstitial fluid (IF)

Answer: C. Intracellular fluid (ICF)

2. What triggers the thirst mechanism in the hypothalamus?

A. Increased plasma osmolality

B. Decreased plasma osmolality by 2–3%

C. Increased blood volume

D. Low body temperature

Answer: B. Decreased plasma osmolality by 2–3%

3. Which hormone promotes sodium reabsorption and potassium secretion?

A. ADH

B. ANP

C. Aldosterone

D. Estrogen

Answer: C. Aldosterone

4. Which electrolyte is most abundant in the intracellular fluid?

A. Na+

B. Ca²⁺

C. Cl⁻

D. K⁺

Answer: D. K⁺

5. What is the major anion in the extracellular fluid?

A. HPO₄²⁻

B. Cl⁻

C. HCO₃⁻

D. SO₄²⁻

Answer: B. Cl⁻

6. Which condition results from excessive water intake or renal insufficiency?

A. Edema

B. Hypovolemia

C. Dehydration

D. Hypotonic hydration

Answer: D. Hypotonic hydration

7. What is the effect of ADH on the kidneys?

A. Increases sodium reabsorption

B. Decreases water reabsorption

C. Increases water reabsorption

D. Stimulates potassium secretion

Answer: C. Increases water reabsorption

8. Which buffer system is the most important in extracellular fluid?

A. Protein buffer system

B. Phosphate buffer system

C. Bicarbonate buffer system

D. Ammonia buffer system

Answer: C. Bicarbonate buffer system

9. Which type of acid-base imbalance is caused by hypoventilation?

A. Respiratory alkalosis

B. Metabolic acidosis

C. Metabolic alkalosis

D. Respiratory acidosis

Answer: D. Respiratory acidosis

10. How do the kidneys compensate for respiratory acidosis?

A. Secreting more bicarbonate

B. Reabsorbing less bicarbonate

C. Retaining bicarbonate ions

D. Decreasing CO₂ elimination

Answer: C. Retaining bicarbonate ions

Acid-Base & Water Balance — Multiple Choice Questions (Set 2)

1. What is the main cation in extracellular fluid (ECF)?

A. K⁺

B. Ca²⁺

C. Na⁺

D. Mg²⁺

Answer: C. Na⁺

2. What happens to cells during dehydration?

A. They swell due to water gain

B. They divide rapidly

C. They lose water and shrink

D. They stop producing ATP

Answer: C. They lose water and shrink

3. Which hormone is released by the heart to lower blood pressure and blood volume?

A. Renin

B. Aldosterone

C. ADH

D. ANP

Answer: D. ANP

4. What condition is characterized by fluid buildup in interstitial spaces?

A. Hypotonic hydration

B. Dehydration

C. Edema

D. Hemolysis

Answer: C. Edema

5. Which buffer system functions primarily in urine and ICF?

A. Bicarbonate buffer system

B. Phosphate buffer system

C. Protein buffer system

D. Respiratory buffer system

Answer: B. Phosphate buffer system

6. Which chemical reaction represents the respiratory regulation of pH?

A. H₂O + NaCl ⇌ Na⁺ + Cl⁻

B. CO₂ + H₂O ⇌ H₂CO₃ ⇌ H⁺ + HCO₃⁻

C. H⁺ + OH⁻ ⇌ H₂O

D. CO₂ ⇌ CO₃²⁻

Answer: B. CO₂ + H₂O ⇌ H₂CO₃ ⇌ H⁺ + HCO₃⁻

7. What happens to pH when CO₂ levels rise in the blood?

A. pH increases

B. pH stays the same

C. pH decreases

D. pH stabilizes at 7.4

Answer: C. pH decreases

8. Which of the following is a cause of metabolic alkalosis?

A. Diabetic ketoacidosis

B. Vomiting of stomach acid

C. Excessive alcohol intake

D. Renal failure

Answer: B. Vomiting of stomach acid

9. Which cells in the nephron secrete H⁺ and reabsorb bicarbonate during acidosis?

A. Type B intercalated cells

B. Principal cells

C. Macula densa cells

D. Type A intercalated cells

Answer: D. Type A intercalated cells

10. What acid-base imbalance is commonly caused by hyperventilation?

A. Metabolic alkalosis

B. Respiratory alkalosis

C. Respiratory acidosis

D. Metabolic acidosis

Answer: B. Respiratory alkalosis

1. Which hormone causes the kidneys to reabsorb water directly?

A. Aldosterone

B. ADH

C. ANP

D. Estrogen

Answer: B. ADH

2. Which of the following best defines acidosis?

A. Arterial blood pH above 7.45

B. Venous blood pH below 7.0

C. Arterial blood pH below 7.35

D. Interstitial fluid pH above 7.4

Answer: C. Arterial blood pH below 7.35

3. What effect does hyperkalemia have on resting membrane potential (RMP)?

A. It makes the RMP more negative

B. It increases responsiveness

C. It causes hyperpolarization

D. It causes depolarization and reduces excitability

Answer: D. It causes depolarization and reduces excitability

4. What electrolyte imbalance may occur with renal failure or excessive ingestion of potassium-rich food?

A. Hypokalemia

B. Hypercalcemia

C. Hyperkalemia

D. Hypochloremia

Answer: C. Hyperkalemia

5. Which buffer system is the most powerful and abundant in intracellular fluid?

A. Bicarbonate buffer system

B. Phosphate buffer system

C. Protein buffer system

D. Respiratory buffer system

Answer: C. Protein buffer system

6. What condition results when blood pH drops below 7.0?

A. Muscle tetany

B. Nervous system excitement

C. CNS depression and possible coma

D. Excessive urine production

Answer: C. CNS depression and possible coma

7. Which renal mechanism generates new bicarbonate ions by excreting ammonium (NH₄⁺)?

A. H⁺ ATPase pump

B. Glutamine metabolism in PCT

C. Phosphate buffering

D. HCO₃⁻-Cl⁻ antiport

Answer: B. Glutamine metabolism in PCT

8. What is the effect of aldosterone on potassium levels?

A. It increases potassium retention

B. It decreases potassium secretion

C. It stimulates potassium secretion

D. It promotes potassium absorption from food

Answer: C. It stimulates potassium secretion

9. Which condition is a result of excess loss of bicarbonate due to diarrhea?

A. Metabolic alkalosis

B. Respiratory alkalosis

C. Metabolic acidosis

D. Respiratory acidosis

Answer: C. Metabolic acidosis

10. What is the normal pH range for arterial blood?

A. 6.8–7.2

B. 7.35–7.45

C. 7.5–8.0

D. 6.5–7.0

Answer: B. 7.35–7.45

Acid-Base & Water Balance — Multiple Choice Questions (Set 4)

1. What is the primary trigger for aldosterone release from the adrenal cortex?

A. High sodium levels

B. Low potassium levels

C. Renin-angiotensin mechanism

D. Hypocalcemia

Answer: C. Renin-angiotensin mechanism

2. What is the role of baroreceptors in water and electrolyte balance?

A. They regulate digestive enzymes

B. They stimulate potassium secretion

C. They alert the brain to blood pressure changes

D. They control bone calcium levels

Answer: C. They alert the brain to blood pressure changes

3. Which ion is secreted in exchange for bicarbonate reabsorption during acidosis?

A. Na⁺

B. Cl⁻

C. K⁺

D. H⁺

Answer: D. H⁺

4. What happens when plasma osmolality increases?

A. Thirst is suppressed

B. ADH release decreases

C. Thirst is triggered and ADH is released

D. Water excretion increases

Answer: C. Thirst is triggered and ADH is released

5. Which of the following contributes to fluid shifts between compartments?

A. Nerve signals

B. Hormone levels only

C. Osmotic and hydrostatic pressure

D. Red blood cell count

Answer: C. Osmotic and hydrostatic pressure

6. Which of the following is a symptom of severe hypotonic hydration?

A. Dry flushed skin

B. Cell shrinkage

C. Cerebral edema

D. Polyuria

Answer: C. Cerebral edema

7. What does hypocalcemia cause?

A. Muscle paralysis

B. Decreased membrane permeability

C. Cardiac arrest

D. Increased excitability and muscle tetany

Answer: D. Increased excitability and muscle tetany

8. Which hormone opposes aldosterone by promoting Na⁺ and water loss?

A. ADH

B. Estrogen

C. ANP

D. Cortisol

Answer: C. ANP

9. Which of the following is a volatile acid removed by the lungs?

A. Phosphoric acid

B. Lactic acid

C. Uric acid

D. Carbonic acid

Answer: D. Carbonic acid

10. What occurs in respiratory alkalosis?

A. Increased CO₂ and low pH

B. Decreased CO₂ and high pH

C. Increased HCO₃⁻

D. High potassium levels

Answer: B. Decreased CO₂ and high pH

Acid-Base & Water Balance — Multiple Choice Questions (Set 5)

1. What is the minimum volume of urine required daily to excrete body wastes?

A. 100 mL

B. 250 mL

C. 500 mL

D. 1,000 mL

Answer: C. 500 mL

2. Which hormone increases NaCl reabsorption similar to aldosterone?

A. Progesterone

B. Estrogen

C. ANP

D. Glucagon

Answer: B. Estrogen

3. What effect does progesterone have on sodium levels?

A. Promotes Na⁺ reabsorption

B. Has no effect

C. Blocks aldosterone and decreases Na⁺ reabsorption

D. Stimulates aldosterone

Answer: C. Blocks aldosterone and decreases Na⁺ reabsorption

4. What is the primary function of phosphate buffering?

A. Buffers ECF

B. Buffers blood plasma

C. Buffers urine and ICF

D. Buffers CO₂ only

Answer: C. Buffers urine and ICF

5. Which of the following is considered a fixed acid that the kidneys must excrete?

A. Carbonic acid

B. Acetic acid

C. Lactic acid

D. Bicarbonate

Answer: C. Lactic acid

6. Which hormone helps the kidneys retain calcium?

A. Aldosterone

B. PTH (Parathyroid Hormone)

C. ANP

D. ADH

Answer: B. PTH (Parathyroid Hormone)

7. What is the effect of high blood pressure on baroreceptors?

A. Activates sympathetic nervous system

B. Stimulates renin release

C. Causes afferent arteriole dilation and Na⁺ excretion

D. Decreases urine formation

Answer: C. Causes afferent arteriole dilation and Na⁺ excretion

8. What happens to HCO₃⁻ during respiratory acidosis with renal compensation?

A. It decreases

B. It increases

C. It remains the same

D. It converts to CO₂

Answer: B. It increases

9. Which of the following conditions causes metabolic acidosis?

A. Hyperventilation

B. Excessive antacid use

C. Starvation and ketone accumulation

D. Vomiting

Answer: C. Starvation and ketone accumulation

10. What happens to breathing during metabolic alkalosis as compensation?

A. Becomes fast and deep

B. Becomes slow and shallow

C. Stops completely

D. Becomes irregular

Answer: B. Becomes slow and shallow

1. What is the primary effect of antidiuretic hormone (ADH)?

A. Increases sodium excretion

B. Stimulates thirst

C. Increases water reabsorption in the kidneys

D. Promotes calcium retention

Answer: C. Increases water reabsorption in the kidneys

2. What causes fluid to leave the capillaries into interstitial space?

A. Low capillary hydrostatic pressure

B. High colloid osmotic pressure

C. High capillary hydrostatic pressure

D. High plasma protein concentration

Answer: C. High capillary hydrostatic pressure

3. Which hormone promotes vasodilation and inhibits renin release?

A. ADH

B. Aldosterone

C. ANP

D. PTH

Answer: C. ANP

4. Which condition causes excessive dilution of extracellular fluid and cellular swelling?

A. Edema

B. Hypovolemia

C. Dehydration

D. Hypotonic hydration

Answer: D. Hypotonic hydration

5. Which of the following is a weak acid in the bicarbonate buffer system?

A. H₂O

B. NaHCO₃

C. H₂CO₃

D. CO₂

Answer: C. H₂CO₃

6. What happens to HCO₃⁻ in the nephron during acidosis?

A. It is secreted

B. It is excreted in urine

C. It is reabsorbed or newly generated

D. It is converted into potassium

Answer: C. It is reabsorbed or newly generated

7. What is the role of respiratory centers in the brainstem during acidosis?

A. Inhibit breathing

B. Increase breathing rate and depth

C. Shut down CO₂ production

D. Increase bicarbonate secretion

Answer: B. Increase breathing rate and depth

8. Which renal cells are active during alkalosis?

A. Type A intercalated cells

B. Juxtaglomerular cells

C. Macula densa

D. Type B intercalated cells

Answer: D. Type B intercalated cells

9. Which hormone increases during low blood pressure and stimulates sodium reabsorption?

A. ANP

B. ADH

C. Renin

D. Aldosterone

Answer: D. Aldosterone

10. Which of the following is a function of phosphate in the body?

A. Major ECF anion

B. Regulates potassium excretion

C. Strong acid buffer in ECF

D. Weak acid buffer in ICF and urine

Answer: D. Weak acid buffer in ICF and urine

1. What is the most abundant solute in body fluids that contributes to osmotic pressure?

A. Glucose

B. Electrolytes

C. Lipids

D. Urea

Answer: B. Electrolytes

2. What term describes a condition where blood plasma proteins are too low, reducing reabsorption at capillaries?

A. Hypovolemia

B. Hypoproteinemia

C. Hyperkalemia

D. Hyponatremia

Answer: B. Hypoproteinemia

3. What is the effect of PTH on the bones?

A. Activates osteoblasts

B. Inhibits calcium absorption

C. Activates osteoclasts to release calcium

D. Decreases phosphate reabsorption

Answer: C. Activates osteoclasts to release calcium

4. What happens in metabolic alkalosis?

A. Blood pH decreases, and HCO₃⁻ drops

B. Blood pH increases, and HCO₃⁻ rises

C. CO₂ levels rise

D. Bicarbonate is eliminated in urine

Answer: B. Blood pH increases, and HCO₃⁻ rises

5. Which electrolyte is closely regulated to prevent cardiac arrhythmias?

A. Calcium

B. Sodium

C. Chloride

D. Potassium

Answer: D. Potassium

6. How does aldosterone respond to high potassium levels in the ECF?

A. Suppresses sodium reabsorption

B. Inhibits ADH release

C. Stimulates potassium secretion

D. Decreases renin production

Answer: C. Stimulates potassium secretion

7. What is the result of a loss of HCO₃⁻ through prolonged diarrhea?

A. Metabolic alkalosis

B. Respiratory alkalosis

C. Respiratory acidosis

D. Metabolic acidosis

Answer: D. Metabolic acidosis

8. Which of the following contributes to insensible water loss?

A. Sweat glands

B. Feces

C. Urine

D. Lungs and skin evaporation

Answer: D. Lungs and skin evaporation

9. Which mechanism compensates for a drop in blood pressure by increasing sodium reabsorption?

A. ANP release

B. Sympathetic inhibition

C. Renin-angiotensin-aldosterone system

D. Hyperventilation

Answer: C. Renin-angiotensin-aldosterone system

10. What are amphoteric molecules, such as proteins, capable of doing?

A. Only donating H⁺

B. Only accepting H⁺

C. Acting as both weak acids and weak bases

D. Preventing osmosis

Answer: C. Acting as both weak acids and weak bases