The story of an orgasm: The physiology of ejaculation
Ejaculation in men is a story of sweat and cheers. Nerves, blood vessels, tissues and friction play important roles. Before we get into the story of the orgasm, let’s quickly review the basic anatomy of the penis.
Running along the length of the penis are two cavernous (like a sponge) chambers, called the corpora cavernosa or the erectile tissues, containing a maze of blood vessels consisting of arteries, several veins and nerves. The urethra, which runs along the underside of the corpora cavernosa, serves as the passageway for urine and ejaculate (sperm and semen). The longest part of the penis is the shaft, and at the end of the shaft is the head (glans penis) that is very sensitive. The opening at the tip of the head where urine and semen are discharged is called the meatus.
The story of the orgasm begins with sensory and mental stimulation in which the brain sends nerve messages to the penis in order to stimulate it and produce an erection. During sexual arousal, impulses from the brain and nerves in the penis cause the arterial muscles of the corpora cavernosa to relax, allowing blood to flow in and fill the open spaces. The blood creates pressure within the corpora cavernosa, making the penis expand, thereby creating an erection. The membrane surrounding the corpora cavernosa, the tunica albuginea, helps trap the blood in the corpora cavernosa, by occluding the venous outflow, and sustain the erection. The erection is lost when arterial muscles in the penis contract after ejaculation, stopping the inflow of blood and opening outflow channels.
Sexual intercourse produces stimulation and friction, which provide the impulses that are delivered to the spinal cord and into the brain. A reflex action controlled by the central nervous system, ejaculation is triggered when the sexual act reaches a critical level of excitement. Ejaculation has two phases. In the first phase, the tubes that store and transport sperm from the testes (vas deferens) contract to squeeze the sperm toward the base of the penis. Simultaneously the prostate gland (walnut-sized gland located between the bladder and the penis, just in front of the rectum) and seminal vesicles (pair of pouch-like glands behind the bladder) release secretions to make seminal fluid. At this stage, ejaculation is unstoppable. In the second phase of ejaculation, muscles at the base of the penis contract every 0.8 seconds and force the semen out of the penis in up to 5 spurts.
On average, ejaculation occurs within 4 to 8 minutes after the start of sexual intercourse. However, many men ejaculate soon after sexual activity and even with the most minimal of penile stimulations and, sometimes, even before actual penetration, a condition called premature ejaculation (PE). One in three men have PE, making it the most common male sexual dysfunction. PE affects both the man and his wife or partner because the sexual activity is not sustained enough to satisfy the man’s partner. Premature ejaculation may lead to dissatisfaction, feelings of inadequacy, displeasure and, oftentimes, misunderstanding. The good news is that a drug to treat PE will soon be available. Aside from medications, psychological and relationship counseling can help manage PE. With their partner’s support and their doctor’s supervision, men can take action and control PE.
Dr. Juliano Z. K. Panganiban is a urologic surgeon and past president of the Philippine Urological Association Inc. A health information advocacy supported by Menarini Philippines,
PE-P Talk is a column series that aims to raise awareness on and enhance understanding of premature ejaculation and its proper diagnosis and treatment. For inquiries, please e-mail [email protected] or visit www.controlPE.ph.
