Sexual behavior is a complex psycho-physiological experience, and there are many factors involved in healthy sexual functioning.

The male sexual response begins when the man becomes aroused and blood flows into the erectile tissue of the penis, causing the penis to swell and become erect.

The male testes will also increase in size and become elevated and the nipples will become erect and sensitive to touch. As excitement increases, there will be a further increase in the size of the glands and the diameter of the penile shaft.

With continued stimulation, the man reaches a peak of sexual pleasure when there is dilation of the prostatic urethra and seminal fluid (sperm) flows into the urethra.

This is accompanied by a sensation of impending orgasm, leading to a rhythmic contraction of the perineal muscles and the pelvic reproductive organs, triggering a forceful ejaculation of semen and sexual release, followed by a state of deep relaxation.

What can go wrong?

Sexual dysfunction may take many forms. The most common problems are Hypoactive Sexual Desire Disorder (low sex drive) and Penile Erectile Dysfunction (difficulties in achieving and maintaining an erection.

While psychological factors can play a big role in sexual problems, studies have suggested that 20 - 50% of men with erectile dysfunction have some organic base for their problem.

The most common organic causes of sexual dysfunction or a low sex drive are:

• Cardiovascular
• Renal or urological
• Nutritional (malnutrition, vitamin deficiency)
• Endocrine (hormonal)
• Neurological
• Pharmacological (alcohol, smoking, recreational and prescription drugs)
• Environmental toxins (lead, herbicides)
• General systemic health problems
• Sexual dysfunction may range from mild (low sex drive, weak erections, lack of energy, slow and weak ejaculation) to severe (total inability to achieve erection and complete lack of sexual desire)