ATI LPN
Questions on the Urinary System Questions
Question 1 of 5
What is the primary role of the detrusor muscle during the resting stage of micturition?
Correct Answer: C
Rationale: During the resting (filling) stage of micturition, the detrusor muscle, a smooth muscle in the bladder wall, contracts minimally and stretches to accommodate urine (C), maintaining continence with sphincter tone. Urination (A) and sphincter relaxation (B) occur during voiding, and control (D) is broader, making C correct.
Question 2 of 5
If the pH is 7.60 (H+ concentration = 25 nEq/L) and the pCO₂ is 40 mmHg, what is the HCO₃- concentration (in mEq/liter).
Correct Answer: D
Rationale: Using Henderson-Hasselbalch: pH = 6.1 + log([HCO₃â»]/(0.03 × pCOâ‚‚)), 7.60 = 6.1 + log([HCO₃â»]/(0.03 × 40)). Solving: 1.5 = log([HCO₃â»]/1.2), 10^1.5 = [HCO₃â»]/1.2, 31.6 ≈ [HCO₃â»]/1.2, [HCO₃â»] ≈ 40 mEq/L. D (40) matches, indicating alkalosis.
Question 3 of 5
Which of the following promotes sodium retention and potassium loss from the blood across the wall of the distal convoluted tubule?
Correct Answer: C
Rationale: Aldosterone (C) increases sodium reabsorption and potassium secretion in the distal tubule, regulating electrolytes. Renin (A) triggers the RAAS, angiotensin II (B) stimulates aldosterone, and angiotensin I (D) is a precursor, making C the direct effector.
Question 4 of 5
Typically, as GFR increases, the [Naâº] of the filtrate reaching the DCT will
Correct Answer: A
Rationale: Higher GFR (A) increases filtrate volume, reducing PCT reabsorption time, raising Na⺠concentration reaching the DCT. Decrease (B) or no change (C) assumes full compensation, but faster flow elevates Naâº, making A correct.
Question 5 of 5
Which of the following is incorrect concerning ADH?
Correct Answer: C
Rationale: ADH increases collecting duct water permeability (C is incorrect), concentrating urine, not decreases it. Osmolarity (A), alcohol (B), and pituitary storage (D) are true, making C the error.