Q&A
1. Which of the following best describes the primary function of the proximal convoluted
tubule in the nephron?
A) Reabsorbing approximately 65% of filtered water, sodium, and glucose
B) Concentrating urine through water reabsorption under ADH influence
C) Secreting hydrogen ions to regulate acid-base balance
D) Filtering blood plasma to form an ultrafiltrate
Correct Answer: Reabsorbing approximately 65% of filtered water, sodium, and glucose
Rationale: The proximal convoluted tubule is the primary site of reabsorption in the nephron,
reclaiming approximately 65% of filtered water, sodium, chloride, and virtually all glucose
and amino acids. It also secretes hydrogen ions and organic acids. The collecting duct
concentrates urine under ADH influence, and the glomerulus filters plasma to form an
ultrafiltrate.
2. What is the primary role of the loop of Henle in urine formation?
A) Reabsorbing glucose and amino acids from the filtrate
B) Creating a concentration gradient in the medulla for urine concentration
C) Secreting potassium and hydrogen ions to regulate pH
D) Filtering blood plasma under hydrostatic pressure
Correct Answer: Creating a concentration gradient in the medulla for urine concentration
Rationale: The loop of Henle establishes a concentration gradient in the renal medulla
through countercurrent multiplication, which is essential for concentrating urine under the
influence of ADH. It reabsorbs water and sodium but is not the primary site of glucose
reabsorption. The glomerulus filters plasma under pressure.
,3. In the context of renal physiology, what is the primary function of the distal convoluted
tubule?
A) Reabsorbing the majority of filtered water and sodium
B) Regulating sodium, potassium, and acid-base balance under hormonal control
C) Filtering blood plasma to form an ultrafiltrate
D) Concentrating urine through water reabsorption
Correct Answer: Regulating sodium, potassium, and acid-base balance under hormonal
control
Rationale: The distal convoluted tubule regulates sodium and potassium reabsorption and
secretion under the influence of aldosterone and regulates acid-base balance through
hydrogen ion secretion. The proximal tubule reabsorbs the majority of filtered water and
sodium. The collecting duct concentrates urine.
4. According to renal principles, what is the primary function of the juxtaglomerular
apparatus?
A) Filtering blood plasma to form an ultrafiltrate
B) Regulating blood pressure through renin secretion
C) Reabsorbing water and electrolytes from the filtrate
D) Concentrating urine through countercurrent multiplication
Correct Answer: Regulating blood pressure through renin secretion
Rationale: The juxtaglomerular apparatus consists of juxtaglomerular cells and the macula
densa. It regulates blood pressure by secreting renin in response to decreased renal perfusion,
which activates the renin-angiotensin-aldosterone system. It does not filter plasma, reabsorb
substances, or concentrate urine directly.
, 5. What is the most likely consequence of a deficiency in antidiuretic hormone (ADH)?
A) Concentrated urine and oliguria
B) Dilute urine and polyuria
C) Hematuria and proteinuria
D) Glycosuria and ketonuria
Correct Answer: Dilute urine and polyuria
Rationale: ADH deficiency causes diabetes insipidus, characterized by the inability to
concentrate urine, leading to excretion of large volumes of dilute urine (polyuria). This can
cause dehydration and hypernatremia. Concentrated urine and oliguria occur with excess
ADH (SIADH).
6. Which term refers to the presence of glucose in the urine?
A) Hematuria
B) Pyuria
C) Glycosuria
D) Proteinuria
Correct Answer: Glycosuria
Rationale: Glycosuria is the presence of glucose in the urine, which occurs when blood
glucose exceeds the renal threshold for reabsorption, typically in uncontrolled diabetes
mellitus. Hematuria is blood in urine, pyuria is pus in urine, and proteinuria is protein in
urine.
7. What is the most likely consequence of a kidney stone obstructing the ureter?
A) Increased glomerular filtration rate