Last updated on August 18, 2020
How is urine kept from coming out of the urethra when a male ejaculates?
When a man becomes sexually aroused his body makes several adjustments in preparation for sexual intercourse.
In his prostate gland, there is a fork in the urethra. One side leads up to the bladder where urine is stored. The other side leads up to the ejaculatory duct. For most of a man’s life, the passage to the bladder is open and the passage to the ejaculatory duct is squeezed close. This prevents urine from back flowing into the ejaculatory duct where the acidic urine would kill his sperm. When a man is sexually aroused, muscles in the prostate gland change the openings. The tube to the bladder is squeezed closed and the tube to the ejaculatory duct opens up. If you have ever seen a railroad track switch, the change operates in a similar fashion. The male body is designed so that only one passage is open at a time. Hence, when a man is strongly aroused, he is unable to urinate.