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Why is ammonia rarely detected in fresh urine?
AThe bladder wall absorbs it back fully
BThe kidneys cannot filter it
CIt evaporates instantly on voiding
DThe liver converts most ammonia into urea
Answer & Solution
Correct answer: D. The liver converts most ammonia into urea
1. Protein breakdown produces ammonia continuously.
2. Most of it is converted into urea by the liver, so fresh urine rarely smells of ammonia.
3. The ammonia smell of old urine comes from bacteria breaking urea back down in the environment.
4. Neither absorption nor filtration failure is the mechanism, which removes those options.
_Source: OpenStax Anatomy and Physiology (CC BY 4.0), Ch 25 "The Urinary System", section Urethra_
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