Sexual Function Glossary of Terms



It is the most abundant protein in the body, accounting for about one-third of its protein composition. Collagen is one of the major building blocks of the skin, bones, muscles, tendons, ligaments, cartilage and connective tissue. Collagen fibers are also found in the tunica albuginea, the fibrous tissue enveloping the penile erectile bodies, which helps achieving the necessary rigidity required for penetration. However, as we age, the body produces less and lower-quality collagen. One of the most visible signs of collagen degradation in the body is less firm and supple facial skin. This process likewise occurs in the tunica albuginea: with age, the number of collagen fibers decreases, the collagen structure changes, resulting in decreased tissue elasticity. The tunica albuginea thus can no longer stretch as before during sexual arousal. Consequently, it cannot effectively prevent blood leaving the erectile bodies, which can lead to erectile dysfunction.


Delayed ejaculation

The term Delayed Ejaculation (DE) encompasses disorders ranging from increased latency to ejaculation to absent ejaculation, including DE. Although there is no clear consensus on what constitutes a reasonable time frame for reaching orgasm, men with latencies beyond 20–25 minutes are assumed to suffer from DE. Reasons include inhibited sexual desire, medical problems such as diabetes (due to neural damage), bladder problems or retrograde ejaculation following prostate gland operation (a situation where an orgasm is experienced), using certain medications (including antidepressants, anti-hypertension drugs and alpha blockers), exaggerated masturbation, age-related decrease in penile sensitivity as well as high stress levels. Treatment will depend on the cause, and usually psycho-sexual therapy coupled with medications may help significantly.


Dopamine is a neurotransmitter which is central to our sexual function. Generally, it is associated with experiencing enjoyment, pleasure and with behaviors involving curiosity, a sense of reward and satisfaction. Therefore, when dopamine is released we experience an “addicting” pleasurable feeling causing us to want more of the same, similar to what we feel after eating chocolate for example. In a similar manner, it is known that dopamine is associated with sexual motivation and function, including sexual arousal/erections and the ability to experience an orgasm (during which high levels of dopamine are released). It is released in brain areas involved in the sexual response and it can trigger penile erection by acting on nerves within the spinal cord that increase blood flow to the penis. Dopamine also affects visual erotic stimuli and fantasy induced erections, which are predominantly controlled by the brain’s reward system. Therefore, it could be assumed that low dopamine levels might undermine sexual arousal, making it difficult to achieve erections and experience enhanced sexual pleasure.



A physiological phenomenon in which the flaccid penis becomes firm, engorged, and enlarged, causing it to stand up and away from the body. Most men have an erection angle between 30° and 120°. An erection is a consequence of a complex physiological process, involving timing and coordination between the vascular system and psychological, neurological and hormonal mechanisms. It occurs when sexual stimulation resulting from touch or thought, passes through like an electrical signal from the brain onto nerve sets along the spinal cord into the penis. That triggers the release of a molecule named Nitric Oxide (NO), which causes the cavernous muscles to relax and blood vessels to expand. Consequently, the blood flow to the penis increases, the cavernosa chambers fill up with blood and the penis gets rigid and erect. At the same time, a chain of biochemical reactions activates an enzyme called PDE5, which is active in the reverse stage, in which the penis turns flaccid again.



A hydrocele is the accumulation of fluids around one or two testicles causing scrotal swelling. Hydroceles are usually congenital though they may form later on in life (usually after 40). They generally don’t pose a threat to the testicles, are painless and tend to disappear without treatment after six months. However, significant scrotal swelling might interfere with the daily activities and with sexual intercourse. An acquired hydrocele usually develops when the channel through which the testicles descend had not closed properly and fluids enter, or if the channel reopens. However, hydroceles can rarely result from inflammation, infection (epididymitis), injury or testicular torsion (a dangerous condition which can lead to tissue necrosis) and therefore it should be diagnosed. A hydrocele usually only needs surgery if it causes significant discomfort or it is suspected to lead to a hernia.

Hypogonadism (in men)

A condition characterized by a deficiency in testosterone. It can originate from testicular failure to produce testosterone – a condition referred to as primary hypogonadism, or when there is a problem in the hypothalamus or the pituitary gland – parts of the brain that signal the testicles to produce testosterone – a condition referred to as secondary hypogonadism. Causes of primary hypogonadism can be congenital (such as undescended testicles) or acquired (such as blunt trauma to the testicles, surgery, chemotherapy, recurrent testicular inflammation etc.). Secondary hypogonadism is caused by an inadequate production of luteinizing hormone (LH) which is responsible for signaling the testes to produce testosterone. This may be due to congenital causes (such as Kalman Syndrome) or acquired (such as severe head injury, a tumor, radiotherapy etc.). Hypogonadism symptoms include lack of libido, erectile dysfunction (including less frequent morning erections), lethargy and lack of energy, concentration problems, depressed mood, reduction in muscle mass and increase in fat tissue, etc.



In the past, it was customary to use interchangeably the terms ‘impotence’ and ‘sexual dysfunction’ to describe the various problems related to each of the phases of the male sexual activity, including sexual desire/libido, sexual arousal/erection, orgasm and ejaculation (and not merely to describe erectile dysfunction as is commonly thought). However, nowadays, the term impotence is hardly used in medical terminology due to its negative connotations.

International Index of Erectile Function (IIEF)

The IIEF is an questionnaire used in the process of evaluating ED and the quality of sex life. It is readily self-administered as part of diagnosing ED and detecting treatment-related changes in patients with ED. Composed of 15 items, the questionnaire addresses the most relevant aspects of male sexual function, including erectile function, orgasmic function, sexual desire, ejaculation, intercourse, and overall sexual satisfaction. The IIEF classifies the severity of ED into five categories stratified by score: No ED, Mild ED, Mild to moderate ED, Moderate ED and Severe ED.



This term refers to our sex drive, or in other words, the desire to have sexual intercourse. Libido is an individual matter and its levels vary greatly among different people. It is affected by various factors such as age, the level of sex hormones the body produces (in men – the level of testosterone), stress levels, tiredness, underlying diseases, the use of medications, the nature of sexual relationships, and the personal beliefs and attitude towards sex.

Low Testosterone

Testosterone is the male sex hormone. Its production starts to increase substantially during puberty, but after the age of 30 its levels begin to drop each year by 1% – as part of the natural aging processes. In men, testosterone is associated with various important functions, including sexual drive (libido), erectile function and morning erections, sperm production, muscle mass, fat distribution, bone density, red blood cells production and more. Because testosterone affects so many functions, low testosterone might cause significant physiological and emotional changes, including low libido, erectile dysfunction (including morning erections), fertility problems, fatigue, low mood, as well as sleep, concentration and mood problems. Low testosterone is treatable with testosterone medications in various forms.


Morning Erection ("morning wood")

Formally known as Nocturnal Penile Tumescence (NPT), it is considered a universal human male trait that happens to men, boys, babies and even to male fetuses in utero. It constitutes a normal and healthy physiological response that reflects an intact neuro-vascular penile function. Morning erections are scientifically defined as involuntary sleep-related erections, because they consist of 3-5 spontaneous erections that occur throughout the night (each lasting for about 25-35 minutes), with the last one being the famous “morning wood”. NPTs are not necessarily associated with erotic dreams, pre-sleep sexual activity or to having a full bladder. Rather, they are related to physiological, neurological and hormonal processes that take place during rapid eye movement (REM) sleep, in which the brain inhibits the activity of the neurotransmitter adrenalin – which is associated with preventing erections. And if there’s nothing to suppress erections, they simply occur spontaneously.


Nitric Oxide (NO)

This is one of the few molecules in the body with a role as a signaling molecule in many organ tissues. It likewise has vasodilating effects, including in the penis, by relaxing the smooth muscle in the endothelium layer of blood vessels. This is done via triggering the formation of a molecule named cGMP within smooth muscle cells which causes blood vessels to expand. Currently there exist a family of prescription medications for the treatment of erectile dysfunction called ‘PDE5 Inhibitors’ which inhibit the enzyme that degrades cGMP, thereby producing continuous relaxation of penile muscle tissue so as to allow an enhanced, prolonged erection.


PDE5 Inhibitors

A class of drugs for the treatment of erectile dysfunction (ED), taken 1-2 hours prior to sexual intercourse. These medications are regarded as one of the most effective forms of ED treatment, with a therapeutic efficacy rate of 70%. The pills increase blood flow to the penis by affecting a natural chemical (called cGMP) involved in dilating blood vessels during sexual arousal. The pills can treat ED caused by various underlying medical conditions, including when nerves and arterial blood vessels leading to the penis are not fully functional. The drugs have different absorption mechanisms and duration of action: two of the drugs exert their effect for approximately 8-12 hours whilst the effect of the third medication lasts up to 36 hours. It’s likewise possible to take one of the pills daily, on the lowest dose. It is noteworthy that the drugs will not trigger an erection  absent sexual stimulation is absent.  

Penile Prosthesis

This is a medical device surgically inserted into the penis through an incision made in the scrotum or under the os pubis, to produce an erect state in cases of erectile dysfunction. However, this form of treatment will only be recommended if all other forms of treatment have failed. The surgery is considered very safe and it has a high success rate of 85-90%. There are two different types of penile implants: Semi-rigid implants – they provide permanent rigidity though they are flexible enough to be curved slightly for concealment.

Inflatable implants – they allow for a more natural erection, as the penis remains flaccid throughout the day. They are composed of a pair of cylinders implanted in the penile corpus cavernosum (the erectile bodies), a pump placed inside the scrotum and a reservoir of saline placed in the lower abdomen. Squeezing the pump will move the fluid into the cylinders in the penis to create an erection.

Penile Pudendal Arteries

The main blood suppliers to the erectile bodies are the internal pudendal arteries. They pass through a relatively long course and they provide numerous branches that supply the structures of the perineum, skin and muscles of the anal and urogenital region, inferior portion of the rectum and the penile erectile bodies. During sexual arousal the pudendal arteries fill up with blood and this ultimately gives rise to an erection. Trauma to the pudendal nerves or their branches might cause erectile dysfunction.

Penile Revascularization Surgery

This operation is suitable for men with ED due to a blocked artery responsible for blood supply of the penis (just like a cardiac bypass), in cases where a single artery is blocked and there are no other underlying risk factors. Causes for penile arterial blockage include pelvic or lower extremity trauma, which can result from a road accident, falls, pelvic injuries, surgeries and even childhood trauma which manifests later on in life. The goal is to restore proper blood flow to the penis by bypassing the blocked artery. The bypass is conducted by connecting an artery in the lower abdomen to an artery at the top of the penis. This is a highly specialized surgery which requires microvascular surgery expertise. The most ideal candidates for this surgery are young men with pelvic trauma which caused a localized common penile artery lesion (blockage or tear). This procedure is not recommended for older men or men with atherosclerosis.

Performance Anxiety

A very common disorder which affects sexual activity in 9-25% of men in various age groups s worldwide. In this condition, a man is often overcome by fear, stress, nervousness and discomfort, believing he will be unable to perform, either before or during sexual activity, and will not satisfy his partner. The problem usually relates to the fact that men perceive sex as “performance” – something they do while being evaluated. This performance mindset leads many men to be self-conscious and self-critical, causing them to feel stress, anxiety and tension while being sexual. However, this usually results in bringing about the very problem they were worrying about in the first place: psychogenic erectile dysfunction, premature ejaculation or alternatively, difficulty getting an orgasm.


The area in the male body extending from the anus to the scrotum where a short part of the urethra passes through as well as several superficial muscles and nerves. Contraction of these muscles helps compress the penile veins, thereby preventing blood outflow from the penis during sexual arousal as part of the erectile mechanism. Perineal trauma as well as frequent long distance bike riding might cause erectile dysfunction. In the latter case, prolong pressure on the perineal area might cause damage to the nerves and blood vessels leading from the pelvis to the penis and reduce blood and oxygen supply to the erectile bodies (corpus cavernosum). In certain circumstances a long bike ride might give rise to Alcock’s Syndrome – characterized as a prolonged glans and penile insensitivity, genital numbness and an erectile dysfunction due to the compression of the pudendal nerve which innervates the penis.

Peyronie's disease

This is a connective tissue disorder, characterized by penile scar tissue formation, curved, shorter and painful (in acute phase) penile erections which result in sexual and erectile dysfunction. It is noteworthy that penile shortening occurs only in the erect state. Peyronie’s disease is quite common, affecting 3-9% of the men usually from the 5th decade of life. It is associated with plaque formation, initially described as focal hardening of the tunica albuginea – the tissue enveloping the penile erectile bodies. Disease expression and course may vary from one patient to another. Studies have shown that in 10-15% of the cases the condition will resolve spontaneously a year after diagnosis, in 40% of the cases it will remain unchanged while 45% of the cases will result in disease aggravation. The disease has an active phase (referred to as the early or inflammatory phase) and a chronic phase (following scar tissue maturation). The active phase is characterized by acute inflammation and pain lasting about 18-24 months, though in most cases the pain will cease spontaneously within 5-7 months. During the chronic phase, areas of calcification are formed and can significantly undermine erectile function. Treatment includes oral medications, penile injections, mechanical stretching of the penis and operations.

Premature/rapid ejaculation

This common condition, involving ejaculation occurring prior to, or a minute after penetration, affects about 15-30% of the men at some stage of their life. The cause is not entirely clear but it seems to involve biological factors, such as  over-sensitivity of the penis coupled with a disruption of serotonin receptors’ activity as well as psychological causes such as anxiety. There is a distinction between primary and secondary premature ejaculation: the former is prevalent in younger men whose unique physiologically triggers erection, orgasm and ejaculation following minimal stimulation, although there might be an improvement upon gaining sexual experience or during long-term relationships. The latter typically occurs among older men without previous ejaculatory problems, due to the development of underlying problems (such as anxiety, obesity, prostate gland problems, thyroid imbalance etc.). In recent years, various creams and medications were developed, which together with psycho-sexual therapy, usually improve symptoms greatly.


Priapism is regarded as a medical emergency requiring urgent treatment. It consists of persistent, painful erection which lasts 4 hours or longer without sexual stimulation, possibly after ejaculation. Untreated priapism for longer than 24 hours can result in significant or irreversible damage to penile tissues, including gangrene and permanent erectile dysfunction. Ischemic priapism, also referred to as low-flow priapism, is the result of blood being trapped in the penis due to restricted blood flow out of the penis. Nonischemic priapism, also referred to as high-flow priapism, is a rarer condition which occurs due to increased blood flow into the penis, often following trauma. Priapism can occur as a result of sickle cell disease (an inherited red blood cell disorder) or as a side effect of medications, including oral PDE5 inhibitors used for treating ED (in 1 out of 1000 people). Treatment usually entails draining execs blood from the penis using a small needle and syringe (aspiration). In certain cases, a medication which constricts blood vessels will be injected into the penis, to allow blood flow out of the organ. Surgery might be required should these treatments prove unsuccessful.


Reflexive erections

The proper function of the erectile mechanism is dependent upon intact nerve conduction from the brain through the spinal cord into the penis. However, any problem along the aforementioned rout can result in difficulties attaining and maintaining an erection. Despite that fact however, some erections, referred to as ‘reflexive erections’, can be generated solely by the spinal cord without brain involvement. Studies have discovered an erection center located between the T12 and S3 vertebrae, which enables achieving a reflexive erection by direct physical stimulation of the penis. In this manner even men with severe or complete spinal cord injury can achieve an erection, as long as the neural circuit in the spinal erection center remains intact.

Root of the penis

The most proximal, fixed part of the penis which is not visible externally. It contains two crura and the bulb of the penis, out of which the erectile tissues extend (the Corpus cavernosum). The root of the penis likewise contains a pair of muscles: one pair contracts to empty the urethra of any residual semen and urine, and it also aids in maintaining erection. The second pair surrounds the left and right crura. When it contracts, it forces blood into the erectile tissues and therefore it plays a role in maintaining an erection. The root of the penis is supported by two ligaments that attach the penis into the middle line of the body and to the pubic bone.


Sexual therapist

This is a qualified counsellor, doctor or healthcare professional (such as a social worker, a psychologist or a psychotherapist with an MA degree) who has completed extra clinical training in helping people coping with sexual dysfunction or otherwise problems with sexual intimacy. Sex therapy can help both individuals and couples. The most common problems which sex therapy focuses on are: sexual dysfunction, including erectile dysfunction, lack of libido, immature or delayed ejaculation, problems with orgasm, performance anxiety, an inability to create intimacy, issues pertaining to sexual and gender identity, sex addiction and more. In Israel there are 1 organizations which train and qualify sex therapists: the Israeli Society for Sexual Therapy (ISST) and 1 scientific society related to sexual medicine; the Israeli Society for Sexual Medicine (ILSSM). The latter qualifies physicians who wish to treat sexual issues from medical point of view. These organizations provide extensive and thorough training courses which abide by internationally accepted standards and practices.


Tunica albuginea

An elastic fibrous layer of connective tissue which gives the penis its cylindrical shape and its ability to change size during sexual arousal. It is likewise an essential structure responsible for penile rigidity during erection. How does it work?  The penile shaft is composed of two erectile bodies called the ‘corpora cavernosa’, which are composed of numerus blood vessels. When the penis is erect, the muscle tissue in those blood vessels relaxes, and the corpora cavernosa fills with blood. Consequently, the blood pressure within them rises and the penis becomes stiff and erect. The tunica albuginea, which envelopes the erectile bodies, stretches during sexual arousal while constricting the penile erection veins (called emissary veins) and preventing blood from leaving the erectile bodies. This is how it sustains the erect state.



A physician who have specialized in diseases of the urinary tract (in both men and women) and of the male reproductive tract, after completing their general degree in medicine. Urology combines the management of medical conditions such as tumors of the urinairy and sexual organs (prostate, bladder etc),urinary-tract and kidney infections, urine incontinence, urinations complaints (urgency and frequency), urinary problems due to obstructive causes such as kidney stones or growths, male sexual dysfunction, including erectile dysfunction and lack of libido, infections in the male genital system, testicular problems (including hydrocele and varicocele), benign prostatic hyperplasia and more. Urology interfaces with other fields of medicine such as oncology, nephrology, gynecology, pediatric surgery, colon and rectal surgery, gastroenterology, endocrinology and more. Some urologists specialize in general urology and some have subspecialties such as: male sexual dysfunction, male infertility, neuro-urology (focusing on problems in the urinary system derived from the nervous system), pediatric urology, urogynecology (conditions involving tumors in the urinary system, testicles and prostate glands) and more.


Vacuum Device

This is a medical device which works on the principle of manually creating a vacuum to achieve an erection. It is used for the treatment of erectile dysfunction in patients who did not respond well enough to drug therapy or those who cannot initiate drug therapy due to health problems.

Treatment is conducted by inserting the penis into a plastic tube. A pump then sucks out the air from the tube so as to create a vacuum, which causes blood to be drawn into the penis and an erection. A soft rubber band is then placed at the base of the penis to maintain the erection after the plastic tube is taken off. This treatment is effective for about 75% of men, regardless of the cause of ED, particularly for those who are still able to achieve partial erections.

However, vacuum devices may not be used in cases of severe blood coagulation disorders or a significant penile curvature.


A varicocele is a dilatation of the veins within the scrotum, called the Pampiniform Plexus – which can occur in one testicle or both. The pampiniform plexus is a loose network of small veins formed by the union of multiple testicular veins. In addition to its function in venous return from the testes, the pampiniform plexus plays a role in temperature regulation of the testes. Varicocele is caused by defective valves in the pampiniform plexus’ veins, leading to blood back up, vein dilatation and disruption of testicular oxygen supply. All of these may (but not in all cases) decrease testicular function and undermine sperm production and quality. There are 4 grades of varicocele. Severe cases might undermine male fertility. There is an age-related increase in varicocele prevalence and the condition is treated by surgery.

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