Final answer:
The lower frequency of cystitis in men compared to women is attributed mainly to the longer length of the male urethra, which provides a stronger barrier to pathogens and is further protected by secretions that buffer the urethral pH.
Step-by-step explanation:
The frequency of cystitis in men is lower than in women because the male urethra is longer than the female urethra. The male urethra, averaging about 20 cm in length, is much longer than the female urethra, which is approximately 4 cm long. This increased length of the male urethra provides a significant barrier to the entry of pathogens, reducing the likelihood of urinary tract infections (UTIs). In contrast, the female urethra's short length and close proximity to the anus makes it easier for fecal bacteria, such as Escherichia coli, to enter the urethra and cause infections.
Additionally, the male urethra is protected by secretions from the prostate gland and Cowper's gland, which help to buffer the urethral pH and protect against extreme pH conditions in urine that may otherwise facilitate bacterial growth. It's worth noting that neither the external nor the internal urethral sphincter's state of contraction is a primary factor in the lower frequency of cystitis in men; rather, it is the anatomy and length of the urethra that play pivotal roles.