Deck 5: Renal and Acidbase Physiology

Question 1

Secretion of $\mathrm{K}^{+}$ by the distal tubule will be decreased by

A) metabolic alkalosis
B) a high- $\mathrm{K}^{+}$ diet
C) hyperaldosteronism
D) spironolactone administration
E) thiazide diuretic administration

Answer 1

spironolactone administration

Question 2

Jared and Adam both weigh $70 \mathrm{~kg}$ . Jared drinks $2 \mathrm{~L}$ of distilled water, and Adam drinks $2 \mathrm{~L}$ of isotonic $\mathrm{NaCl}$ . As a result of these ingestions, Adam will have a

A) greater change in intracellular fluid (ICF) volume
B) higher positive free-water clearance $\left(\mathrm{C}_{\mathrm{H}_{2} \mathrm{O}}\right)$
C) greater change in plasma osmolarity
D) higher urine osmolarity
E) higher urine flow rate

Answer 2

higher urine osmolarity

Question 3

A 45-year-old woman develops severe diarrhea while on vacation. She has the following arterial blood values:
$\mathrm{pH}=7.25$
$\mathrm{Pco}_{2}=24 \mathrm{~mm} \mathrm{Hg}$
$\left[\mathrm{HCO}_{3}^{-}\right]=10 \mathrm{mEq} / \mathrm{L}$
Venous blood samples show decreased blood $\left[\mathrm{K}^{+}\right]$ and a normal anion gap.

-The correct diagnosis for this patient is

A) metabolic acidosis
B) metabolic alkalosis
C) respiratory acidosis
D) respiratory alkalosis
E) normal acid-base status

Answer 3

metabolic acidosis

Question 4

A 45-year-old woman develops severe diarrhea while on vacation. She has the following arterial blood values:
$\mathrm{pH}=7.25$
$\mathrm{Pco}_{2}=24 \mathrm{~mm} \mathrm{Hg}$
$\left[\mathrm{HCO}_{3}^{-}\right]=10 \mathrm{mEq} / \mathrm{L}$
Venous blood samples show decreased blood $\left[\mathrm{K}^{+}\right]$ and a normal anion gap.

-Which of the following statements about this patient is correct?

A) She is hypoventilating
B) The decreased arterial $\left[\mathrm{HCO}_{3}^{-}\right]$ is a result of buffering of excess $\mathrm{H}^{+}$ by $\mathrm{HCO}_{3}^{-}$
C) The decreased blood $\left[\mathrm{K}^{+}\right]$ is a result of exchange of intracellular $\mathrm{H}^{+}$ for extracellular $\mathrm{K}^{+}$
D) The decreased blood $\left[\mathrm{K}^{+}\right]$ is a result of increased circulating levels of aldosterone
E) The decreased blood $\left[\mathrm{K}^{+}\right]$ is a result of decreased circulating levels of antidiuretic hormone (ADH)

Question 5

Use the values below to answer the following question.
Glomerular capillary hydrostatic pressure $=$ $47 \mathrm{~mm} \mathrm{Hg}$
Bowman space hydrostatic pressure $=$ $10 \mathrm{~mm} \mathrm{Hg}$
Bowman space oncotic pressure $=0 \mathrm{~mm} \mathrm{Hg}$ At what value of glomerular capillary oncotic pressure would glomerular filtration stop?

A) $57 \mathrm{~mm} \mathrm{Hg}$
B) $47 \mathrm{~mm} \mathrm{Hg}$
C) $37 \mathrm{~mm} \mathrm{Hg}$
D) $10 \mathrm{~mm} \mathrm{Hg}$
E) $0 \mathrm{~mm} \mathrm{Hg}$

Question 6

The reabsorption of filtered $\mathrm{HCO}_{3}^{-}$

A) results in reabsorption of less than $50 \%$ of the filtered load when the plasma concentration of $\mathrm{HCO}_{3}{ }^{-}$ is $24 \mathrm{mEq} / \mathrm{L}$
B) acidifies tubular fluid to a $\mathrm{pH}$ of 4.4
C) is directly linked to excretion of $\mathrm{H}^{+}$ as $\mathrm{NH}_{4}^{+}$
D) is inhibited by decreases in arterial $\mathrm{Pco}_{2}$
E) can proceed normally in the presence of a renal carbonic anhydrase inhibitor

Question 7

The following information was obtained in a 20 -year-old college student who was participating in a research study in the Clinical Research Unit:

Assuming that $\mathrm{X}$ is freely filtered, which of the following statements is most correct?

A) There is net secretion of $\mathrm{X}$
B) There is net reabsorption of $\mathrm{X}$
C) There is both reabsorption and secretion of $X$
D) The clearance of $X$ could be used to measure the glomerular filtration rate (GFR)
E) The clearance of $\mathrm{X}$ is greater than the clearance of inulin

Question 8

To maintain normal $\mathrm{H}^{+}$ balance, total daily excretion of $\mathrm{H}^{+}$ should equal the daily

A) fixed acid production plus fixed acid ingestion
B) $\mathrm{HCO}_{3}^{-}$ excretion
C) $\mathrm{HCO}_{3}{ }^{-}$ filtered load
D) titratable acid excretion
E) filtered load of $\mathrm{H}^{+}$

Question 9

One gram of mannitol was injected into a woman. After equilibration, a plasma sample had a mannitol concentration of $0.08 \mathrm{~g} / \mathrm{L}$ . During the equilibration period, $20 \%$ of the injected mannitol was excreted in the urine. The woman's

A) extracellular fluid (ECF) volume is $1 \mathrm{~L}$
B) intracellular fluid (ICF) volume is $1 \mathrm{~L}$
C) ECF volume is $10 \mathrm{~L}$
D) ICF volume is $10 \mathrm{~L}$
E) interstitial volume is $12.5 \mathrm{~L}$

Question 10

A 58-year-old man is given a glucose tolerance test. In the test, the plasma glucose concentration is increased and glucose reabsorption and excretion are measured. When the plasma glucose concentration is higher than occurs at transport maximum $\left(\mathrm{T}_{\mathrm{m}}\right)$ , the

A) clearance of glucose is zero
B) excretion rate of glucose equals the filtration rate of glucose
C) reabsorption rate of glucose equals the filtration rate of glucose
D) excretion rate of glucose increases with increasing plasma glucose concentrations
E) renal vein glucose concentration equals the renal artery glucose concentration

Question 11

A negative free-water clearance $\left(-\mathrm{C}_{\mathrm{H}_{2} \mathrm{O}}\right)$ will occur in a person who

A) drinks $2 \mathrm{~L}$ of distilled water in 30 minutes
B) begins excreting large volumes of urine with an osmolarity of $100 \mathrm{mOsm} / \mathrm{L}$ after a severe head injury
C) is receiving lithium treatment for depression and has polyuria that is unresponsive to the administration of antidiuretic hormone (ADH)
D) has an oat cell carcinoma of the lung, and excretes urine with an osmolarity of $1,000 \mathrm{mOsm} / \mathrm{L}$

Question 12

A buffer pair (HA/A $\left.\mathrm{A}^{-}\right)$ has a $\mathrm{pK}$ of 5.4. At a blood $\mathrm{pH}$ of 7.4, the concentration of HA is

A) $1 / 100$ that of $\mathrm{A}^{-}$
B) $1 / 10$ that of $\mathrm{A}^{-}$
C) equal to that of $\mathrm{A}^{-}$
D) 10 times that of $\mathrm{A}^{-}$
E) 100 times that of $\mathrm{A}^{-}$

Question 13

Which of the following would produce an increase in the reabsorption of isosmotic fluid in the proximal tubule?

A) Increased filtration fraction
B) Extracellular fluid (ECF) volume expansion
C) Decreased peritubular capillary protein concentration
D) Increased peritubular capillary hydrostatic pressure
E) Oxygen deprivation

Question 14

Which of the following substances or combinations of substances could be used to measure interstitial fluid volume?

A) Mannitol
B) $\mathrm{D}_{2} \mathrm{O}$ alone
C) Evans blue
D) Inulin and $\mathrm{D}_{2} \mathrm{O}$
E) Inulin and radioactive albumin

Question 15

At plasma para-aminohippuric acid (PAH) concentrations below the transport maximum $\left(\mathrm{T}_{\mathrm{m}}\right)$ , PAH

A) reabsorption is not saturated
B) clearance equals inulin clearance
C) secretion rate equals $\mathrm{PAH}$ excretion rate
D) concentration in the renal vein is close to zero
E) concentration in the renal vein equals $\mathrm{PAH}$ concentration in the renal artery

Question 16

Compared with a person who ingests $2 \mathrm{~L}$ of distilled water, a person with water deprivation will have a

A) higher free-water clearance $\left(\mathrm{C}_{\mathrm{H}_{2} \mathrm{O}}\right)$
B) lower plasma osmolarity
C) lower circulating level of antidiuretic hormone (ADH)
D) higher tubular fluid/plasma (TF/P) osmolarity in the proximal tubule
E) higher rate of $\mathrm{H}_{2} \mathrm{O}$ reabsorption in the collecting ducts

Question 17

Which of the following would cause an increase in both glomerular filtration rate (GFR) and renal plasma flow (RPF)?

A) Hyperproteinemia
B) A ureteral stone
C) Dilation of the afferent arteriole
D) Dilation of the efferent arteriole
E) Constriction of the efferent arteriole

Question 18

A patient has the following arterial blood values:
$\mathrm{pH}=7.52$
$\mathrm{Pco}_{2}=20 \mathrm{~mm} \mathrm{Hg}$
$\left[\mathrm{HCO}_{3}{ }^{-}\right]=16 \mathrm{mEq} / \mathrm{L}$
Which of the following statements about this patient is most likely to be correct?

A) He is hypoventilating
B) He has decreased ionized $\left[\mathrm{Ca}^{2+}\right]$ in blood
C) He has almost complete respiratory compensation
D) He has an acid-base disorder caused by overproduction of fixed acid
E) Appropriate renal compensation would cause his arterial $\left[\mathrm{HCO}_{3}^{-}\right]$ to increase

Question 19

Which of the following would best distinguish an otherwise healthy person with severe water deprivation from a person with the syndrome of inappropriate antidiuretic hormone (SIADH)?

A) Free-water clearance $\left(\mathrm{C}_{\mathrm{H}_{2} \mathrm{O}}\right)$
B) Urine osmolarity
C) Plasma osmolarity
D) Circulating levels of antidiuretic hormone (ADH)
E) Corticopapillary osmotic gradient

Question 20

Which of the following causes a decrease in renal $\mathrm{Ca}^{2+}$ clearance?

A) Hypoparathyroidism
B) Treatment with chlorothiazide
C) Treatment with furosemide
D) Extracellular fluid (ECF) volume expansion
E) Hypermagnesemia

Question 21

A patient arrives at the emergency room with low arterial pressure, reduced tissue turgor, and the following arterial blood values:
$\mathrm{pH}=7.69$
$\left[\mathrm{HCO}_{3}{ }^{-}\right]=57 \mathrm{mEq} / \mathrm{L}$
$\mathrm{PCO}_{2}=48 \mathrm{~mm} \mathrm{Hg}$
Which of the following responses would also be expected to occur in this patient?

A) Hyperventilation
B) Decreased $\mathrm{K}^{+}$ secretion by the distal tubules
C) Increased ratio of $\mathrm{H}_{2} \mathrm{PO}_{4}^{-}$ to $\mathrm{HPO}_{4}^{-2}$ in urine
D) Exchange of intracellular $\mathrm{H}^{+}$ for extracellular $\mathrm{K}^{+}$

Question 22

A woman has a plasma osmolarity of $300 \mathrm{mOsm} / \mathrm{L}$ and a urine osmolarity of 1200 $\mathrm{mOsm} / \mathrm{L}$ . The correct diagnosis is

A) syndrome of inappropriate antidiuretic hormone (SIADH)
B) water deprivation
C) central diabetes insipidus
D) nephrogenic diabetes insipidus
E) drinking large volumes of distilled water

Question 23

A patient is infused with paraaminohippuric acid (PAH) to measure renal blood flow (RBF). She has a urine flow rate of $1 \mathrm{~mL} / \mathrm{min}$ , a plasma [PAH] of $1 \mathrm{mg} / \mathrm{mL}$ , a urine $[\mathrm{PAH}]$ of $600 \mathrm{mg} / \mathrm{mL}$ , and a hematocrit of $45 \%$ . What is her "effective" RBF?

A) $600 \mathrm{~mL} / \mathrm{min}$
B) $660 \mathrm{~mL} / \mathrm{min}$
C) $1,091 \mathrm{~mL} / \mathrm{min}$
D) $1,333 \mathrm{~mL} / \mathrm{min}$

Question 24

Which of the following substances has the highest renal clearance?

A) Para-aminohippuric acid (PAH)
B) Inulin
C) Glucose
D) $\mathrm{Na}^{+}$
E) $\mathrm{Cl}^{-}$

Question 25

A woman runs a marathon in $90^{\circ} \mathrm{F}$ weather and replaces all volume lost in sweat by drinking distilled water. After the marathon, she will have

A) decreased total body water (TBW)
B) decreased hematocrit
C) decreased intracellular fluid (ICF) volume
D) decreased plasma osmolarity
E) increased intracellular osmolarity

Question 26

Which of the following causes hyperkalemia?

A) Exercise
B) Alkalosis
C) Insulin injection
D) Decreased serum osmolarity
E) Treatment with $\beta$ -agonists

Question 27

Which of the following is a cause of metabolic alkalosis?

A) Diarrhea
B) Chronic renal failure
C) Ethylene glycol ingestion
D) Treatment with acetazolamide
E) Hyperaldosteronism
F) Salicylate poisoning

Question 28

Which of the following is an action of parathyroid hormone (PTH) on the renal tubule?

A) Stimulation of adenylate cyclase
B) Inhibition of distal tubule $\mathrm{K}^{+}$ secretion
C) Inhibition of distal tubule $\mathrm{Ca}^{2+}$ reabsorption
D) Stimulation of proximal tubule phosphate reabsorption
E) Inhibition of production of 1,25-dihydroxycholecalciferol

Question 29

A man presents with hypertension and hypokalemia. Measurement of his arterial blood gases reveals a $\mathrm{pH}$ of 7.5 and a calculated $\mathrm{HCO}_{3}$ - of $32 \mathrm{mEq} / \mathrm{L}$ . His serum cortisol and urinary vanillylmandelic acid (VMA) are normal, his serum aldosterone is increased, and his plasma renin activity is decreased. Which of the following is the most likely cause of his hypertension?

A) Cushing syndrome
B) Cushing disease
C) Conn syndrome
D) Renal artery stenosis
E) Pheochromocytoma

Question 30

Which set of arterial blood values describes a heavy smoker with a history of emphysema and chronic bronchitis who is becoming increasingly somnolent?
$\quad \quad \mathrm{pH} \quad \mathrm{HCO}_{3}^{-}(\mathrm{mEq} / \mathrm{L}) \quad \mathrm{PcO}_{2}(\mathrm{~mm} \mathrm{Hg})$

A) $\begin{array}{lll}7.65 \quad \quad & 48 & \quad \quad \quad \quad \quad \quad 45\end{array}$
B) $\begin{array}{lll}7.50 & \quad \quad 15 & \quad \quad \quad \quad \quad \quad 20\end{array}$
C) $\begin{array}{lll}7.40 & \quad \quad 24 & \quad \quad \quad \quad \quad \quad 40\end{array}$
D) $\begin{array}{lll}7.32 \quad \quad & 30 & \quad \quad \quad \quad \quad \quad 60\end{array}$
E) $\begin{array}{lll}7.31 & \quad \quad 16 & \quad \quad \quad \quad \quad \quad 33\end{array}$

Question 31

Which set of arterial blood values describes a patient with partially compensated respiratory alkalosis after 1 month on a mechanical ventilator?
$\quad \quad \mathrm{pH} \quad \mathrm{HCO}_{3}^{-}(\mathrm{mEq} / \mathrm{L}) \quad \mathrm{PcO}_{2}(\mathrm{~mm} \mathrm{Hg})$

A) $\begin{array}{lll}7.65 & \quad \quad 48 & \quad \quad \quad \quad \quad \quad 45\end{array}$
B) $\begin{array}{lll}7.50 & \quad \quad 15 & \quad \quad \quad \quad \quad \quad 20\end{array}$
C) $\begin{array}{lll}7.40 & \quad \quad 24 & \quad \quad \quad \quad \quad \quad 40\end{array}$
D) $\begin{array}{lll}7.32 & \quad \quad 30 & \quad \quad \quad \quad \quad \quad 60\end{array}$
E) $\begin{array}{lll}7.31 & \quad \quad 16 & \quad \quad \quad \quad \quad \quad 33\end{array}$

Question 32

Which set of arterial blood values describes a patient with chronic renal failure (eating a normal protein diet) and decreased urinary excretion of $\mathrm{NH}_{4}^{+}$ ?
$\quad \quad \mathrm{pH} \quad \mathrm{HCO}_{3}^{-}(\mathrm{mEq} / \mathrm{L}) \quad \mathrm{PcO}_{2}(\mathrm{~mm} \mathrm{Hg})$

A) $\begin{array}{lll}7.65 & \quad \quad 48 & \quad \quad \quad \quad \quad \quad 45\end{array}$
B) $\begin{array}{lll}7.50 & \quad \quad 15 & \quad \quad \quad \quad \quad \quad 20\end{array}$
C) $\begin{array}{lll}7.40 & \quad \quad 24 & \quad \quad \quad \quad \quad \quad 40\end{array}$
D) $\begin{array}{lll}7.32 & \quad \quad 30 & \quad \quad \quad \quad \quad \quad 60\end{array}$
E) $\begin{array}{lll}7.31 & \quad \quad 16 & \quad \quad \quad \quad \quad \quad 33\end{array}$

Question 33

Which set of arterial blood values describes a patient with untreated diabetes mellitus and increased urinary excretion of $\mathrm{NH}_{4}{ }^{+}$ ?
$\quad \quad \mathrm{pH} \quad \mathrm{HCO}_{3}^{-}(\mathrm{mEq} / \mathrm{L}) \quad \mathrm{PcO}_{2}(\mathrm{~mm} \mathrm{Hg})$

A) $\begin{array}{lll}7.65 & \quad \quad 48 & \quad \quad \quad \quad \quad \quad 45\end{array}$
B) $\begin{array}{lll}7.50 & \quad \quad 15 & \quad \quad \quad \quad \quad \quad 20\end{array}$
C) $\begin{array}{lll}7.40 & \quad \quad 24 & \quad \quad \quad \quad \quad \quad 40\end{array}$
D) $\begin{array}{lll}7.32 & \quad \quad 30 & \quad \quad \quad \quad \quad \quad 60\end{array}$
E) $\begin{array}{lll}7.31 & \quad \quad 16 & \quad \quad \quad \quad \quad \quad 33\end{array}$

Question 34

Which set of arterial blood values describes a patient with a 5-day history of vomiting?

$\quad \quad \mathrm{pH} \quad \mathrm{HCO}_{3}^{-}(\mathrm{mEq} / \mathrm{L}) \quad \mathrm{PcO}_{2}(\mathrm{~mm} \mathrm{Hg})$

A) $\begin{array}{lll}7.65 & \quad \quad 48 & \quad \quad \quad \quad \quad \quad 45\end{array}$
B) $\begin{array}{lll}7.50 & \quad \quad 15 & \quad \quad \quad \quad \quad \quad 20\end{array}$
C) $\begin{array}{lll}7.40 & \quad \quad 24 & \quad \quad \quad \quad \quad \quad 40\end{array}$
D) $\begin{array}{lll}7.32 & \quad \quad 30 & \quad \quad \quad \quad \quad \quad 60\end{array}$
E) $\begin{array}{lll}7.31 & \quad \quad 16 & \quad \quad \quad \quad \quad \quad 33\end{array}$

Question 35

-At which nephron site does the amount of $\mathrm{K}^{+}$ in tubular fluid exceed the amount of filtered $\mathrm{K}^{+}$ in a person on a high- $\mathrm{K}^{+}$ diet?

A) Site A
B) Site B
C) Site C
D) Site D
E) Site E

Question 36

-At which nephron site is the tubular fluid/plasma (TF/P) osmolarity lowest in a person who has been deprived of water?

A) Site A
B) Site B
C) Site C
D) Site D
E) Site E

Question 37

-At which nephron site is the tubular fluid inulin concentration highest during antidiuresis?

A) Site A
B) Site B
C) Site C
D) Site D
E) Site E

Question 38

-At which nephron site is the tubular fluid inulin concentration lowest?

A) Site A
B) Site B
C) Site C
D) Site D
E) Site E

Question 39

-At which nephron site is the tubular fluid glucose concentration highest?

A) Site A
B) Site B
C) Site C
D) Site D
E) Site E

Question 40

The curves show the percentage of the filtered load remaining in the tubular fluid at various sites along the nephron.


-Which curve describes the inulin profile along the nephron?

A) Curve A
B) Curve B
C) Curve C
D) Curve D

Question 41

The curves show the percentage of the filtered load remaining in the tubular fluid at various sites along the nephron.


-Which curve describes the alanine profile along the nephron?

A) Curve A
B) Curve B
C) Curve C
D) Curve D

Question 42

The curves show the percentage of the filtered load remaining in the tubular fluid at various sites along the nephron.


-Which curve describes the paraaminohippuric acid $(\mathrm{PAH})$ profile along the nephron?

A) Curve A
B) Curve B
C) Curve C
D) Curve D

Question 43

A 5-year-old boy swallows a bottle of aspirin (salicylic acid) and is treated in the emergency room. The treatment produces a change in urine $\mathrm{pH}$ that increases the excretion of salicylic acid. What was the change in urine $\mathrm{pH}$ , and what is the mechanism of increased salicylic acid excretion?

A) Acidification, which converts salicylic acid to its HA form
B) Alkalinization, which converts salicylic acid to its $\mathrm{A}^{-}$ form
C) Acidification, which converts salicylic acid to its $\mathrm{A}^{-}$ form
D) Alkalinization, which converts salicylic acid to its HA form