Question 1

Which of the following best describes the primary function of the nephron loop (loop of Henle) in juxtamedullary nephrons?

Accepted Answer

It establishes an osmotic gradient in the renal medulla, essential for concentrating urine.

Question 2

A patient presents with a plasma pH of 7.28 and rapid, shallow breathing. Which acid-base disorder is most likely present, and what is the primary physiological cause?

Accepted Answer

Respiratory acidosis due to hypoventilation and CO$$_2$$ retention.

Question 3

Which hormone increases the permeability of the distal convoluted tubule (DCT) and collecting duct to water, and what is the effect on urine volume?

Accepted Answer

Antidiuretic hormone (ADH); decreases urine volume by increasing water reabsorption.

Question 4

A kidney stone obstructs the left ureter. Which of the following best describes the consequence of this obstruction?

Accepted Answer

Urine flow from the renal pelvis to the urinary bladder is blocked.

Question 5

Which of the following best explains why patients with chronic renal failure often develop anemia?

Accepted Answer

The kidneys produce less erythropoietin, reducing red blood cell production.

Question 6

Which of the following is the correct sequence of blood flow through the kidney, starting from the renal artery?

Accepted Answer

Renal artery → segmental arteries → interlobar arteries → arcuate arteries → cortical radiate arteries → afferent arterioles → glomerulus

Question 7

A patient is experiencing polyuria (excessive urine output) with very dilute urine. Which of the following is the most likely explanation?

Accepted Answer

Decreased ADH secretion is preventing facultative water reabsorption in the DCT and collecting duct.

Question 8

Which of the following best describes the role of the vasa recta in the kidney?

Accepted Answer

It maintains the concentration gradient of the renal medulla by absorbing solutes and water.

Question 9

Which of the following buffer systems is most important for buffering acids produced by metabolic activity in the extracellular fluid?

Accepted Answer

Carbonic acid–bicarbonate buffer system

Question 10

A patient with severe diarrhea is losing large amounts of bicarbonate ions (HCO$$_3^-). $$Which acid-base disorder is most likely to develop, and what is a compensatory response?

Accepted Answer

Metabolic acidosis; increased respiratory rate to expel CO$$_2.$$

Question 11

Which of the following best describes the process of hemodialysis?

Accepted Answer

Passive diffusion of solutes and water across a selectively permeable artificial membrane to regulate blood composition.

Question 12

Which of the following changes would occur if aldosterone secretion increases?

Accepted Answer

More sodium ions would be reabsorbed in the DCT and collecting duct, increasing ECF volume.

Question 13

Which of the following is a correct statement about obligatory and facultative water reabsorption in the nephron?

Accepted Answer

Obligatory water reabsorption occurs in the PCT and nephron loop and cannot be prevented, while facultative water reabsorption occurs in the DCT and collecting duct and is regulated by ADH.

Question 14

A patient with a plasma pH of 7.50 is experiencing muscle twitching and irritability. Which acid-base disorder is present, and what is a likely cause?

Accepted Answer

Alkalosis; excessive loss of hydrogen ions due to prolonged vomiting.

Question 15

Which of the following best explains why severe proteinuria (protein in urine) can lead to generalized edema?

Accepted Answer

Loss of plasma proteins reduces blood osmotic pressure, causing fluid to accumulate in tissues.

Question 16

Which of the following events must occur to allow voluntary urination (micturition)?

Accepted Answer

Contraction of the detrusor muscle and voluntary relaxation of the external urethral sphincter.

Question 17

Which of the following best describes the effect of increased CO$$_2$$ levels on blood pH?

Accepted Answer

Increased CO$$_2$$ lowers blood pH, causing acidosis.

Question 18

Which of the following is a function of the urinary system that helps maintain homeostasis?

Accepted Answer

Regulation of plasma concentrations of sodium, potassium, and chloride ions.

Question 19

Which of the following best describes the difference between acute and chronic renal failure?

Accepted Answer

Acute renal failure is often reversible if the underlying cause is treated, while chronic renal failure is progressive and irreversible.

The Urinary System and Fluid, Electrolyte, and Acid-Base Balance

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