To fully understand how your prostate cancer or prostate cancer treatment may affect you, it is helpful to know about normal male sexual function.
There are four stages of healthy male sexual performance:
1. sexual desire or libido
2. erectile function
3. orgasm and ejaculation
4. resolution and refractory period.
SEXUAL DESIRE OR LIBIDO
Sexual desire, libido and sex drive are all essentially a man’s desire for sex.
There are a number of factors that can affect sexual desire, both physical and emotional. These can include:
- anxiety or depression
- relationship problems
- erectile dysfunction
- premature ejaculation
- certain types of medication.
The hormone testosterone is produced mainly in the testes and is the main driver of sexual desire. When the testosterone levels drop, sex drive will diminish. Testosterone levels decrease with age or as a result of illness or treatment, and in particular after hormone therapy for prostate cancer. For more information about hormone therapy see page 13 – or refer to the PCFA booklet Understanding hormone therapy for prostate cancer (www.pcfa.org.au).
There are two cylinders of spongy tissues that run either side of the penis (corpus cavernosum). The third cylinder (corpus spongiosum) runs along the underside of the penis and surrounds the urethra (urine tube).
CROSS SECTION OF A PENIS
During an erection, a man first becomes sexually aroused. The brain sends messages down the spinal cord and through nerves located near the prostate to tell the blood vessels to let more blood into the spongy cylinders. As these cylinders expand and fill with blood, an erection occurs.
NOTE: A failure of this process, for any reason, is referred to as erectile dysfunction (ED). In medical terms, ED is described as the inability to achieve or maintain an erection firm enough for sexual activity or penetration.
ORGASM AND EJACULATION
After continued sexual stimulation, men usually experience orgasm. Sexual pleasure peaks, accompanied by rhythmic pelvic muscle contractions followed by ejaculation of semen. Semen is then pushed through the urethra and out of the end of the penis. The muscle or valve at the opening of the bladder closes during ejaculation to stop the backflow of semen into the bladder. This valve also stops urine and semen passing down the urethra at the same time.
Note: Before ejaculation, sperm is mixed with fluid from the seminal vesicles and the prostate. Sperm and seminal fluid together make semen.
RESOLUTION AND REFRACTORY PERIOD
After orgasm and ejaculation the erection subsides. The man then enters a recovery period, during which another erection or orgasm is not possible for a period of time. This resting time becomes longer with age. A young man may be able to regain an erection within several minutes whereas for an older man this time period may range from hours to days.