Which of the following is a defense mechanism of the urinary tract that helps prevent microbial infection?

• A. Presence of ciliated epithelial cells
• B. Flushing action of urine
• C. Production of hydrochloric acid
• D. Secretion of lysozyme in saliva

Answer: (B)

Verified step by step guidance

1. Identify the anatomical and physiological features of the urinary tract that contribute to defense against microbial infection.
2. Understand that ciliated epithelial cells are typically found in the respiratory tract, not the urinary tract, so this is unlikely to be a defense mechanism here.
3. Recall that hydrochloric acid production is a defense mechanism primarily in the stomach, where it lowers pH to kill microbes, not in the urinary tract.
4. Recognize that lysozyme secretion in saliva is a defense mechanism of the oral cavity, not the urinary tract.
5. Focus on the flushing action of urine, which physically removes microbes from the urinary tract, preventing their colonization and infection—this is the key defense mechanism in the urinary tract.