Answer: The kidneys cannot filter and excrete urea efficiently.
- A The liver has stopped producing urea from ammonia
- B The urinary bladder fails to store urine properly
- C Urea is being overproduced by the pancreas instead
- D The kidneys cannot filter and excrete urea efficiently
Correct answer: D. The kidneys cannot filter and excrete urea efficiently
Explanation: Uremia results from impaired kidney function, in which urea and other nitrogenous wastes are not adequately filtered out of the blood, leading to their accumulation and potential toxicity.
Filtrate flows through four functionally distinct stages of the nephron: Bowman's capsule filters blood, the PCT reabsorbs most useful substances unconditionally, the Loop of Henle builds a concentration gradient via counter-current exchange, the DCT secretes selected substances, and the collecting duct performs the final ADH-controlled water reabsorption.
Concept context
Nitrogenous waste, kidney structure, urine formation in the nephron, and hormonal regulation of excretion.
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