Question

The internal urethral sphincter closes (constricts) during ejaculation. This serves to…

Group of answer choices

A. prevent the discharge of urine during ejaculation

B. prevent semen from entering the bladder

C. prevent the discharge of seminal fluid during ejaculation

A and B

A and C

Answer 1

Answer: A and B.

- The internal urethral sphincter constricts during ejaculation to prevent the discharge of urine during ejaculation as well as to prevent the semen from entering the bladder.

- The internal urethral sphincter is one of the two urethral spincter muscles (other being the external urethral sphincter). It is located at the junction of urinary bladder and beginning of urethra. It is composed of smooth muscles and is under sympathetic autonomic nervous system control.

- During ejaculation, which is a sympathetic nervous system activity, the internal urethral sphincter constricts which prevents the passage of urine from the urinary bladder into the urethra. The constriction of internal urethral sphincter also prevents the backflow of semen from the urethra into the urinary bladder, condition known as retrograde ejaculation.