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Selective inhibitors of type 5 phosphodiesterase sildenafil, tadalafil, vardenafil, and avanafil , which is preferentially distributed in the penis, enhance cavernosal smooth-muscle cell relaxation when impaired and have proven effective in the treatment of erectile dysfunction.
Guanylate cyclase is activated by direct action of NO Hobbs, Adenylate cyclase is activated by Gs protein, liberated after interaction between VIP or prostanoids and the corresponding protein G-coupled receptor Andersson, Another mechanism responsible for smooth-muscle cell relaxation is hyperpolarization.
It causes closure of voltage-dependent calcium channels, resulting in decreased calcium entry from the extracellular milieu and lower cytoplasmic calcium levels Fig. Regulation of potassium channel opening is dependent on cyclic nucleotides both cGMP and cAMP , whereas activity of the sodium pump can be modulated by direct action of NO Christ et al. Activation of the phospholipase C intracellular signaling pathway including inositol triphosphate and protein kinase C as second messengers induces calcium release from sarcoplasmic reticulum, opening of L-type calcium channels, and closure of potassium channels depolarization , leading to smooth-muscle cell contraction.
Because smooth-muscle fibers of the penile erectile tissues are connected with gap junctions, it is not required for chemical messengers to reach all of the cells to elicit a global effect. Indeed, gap junctions allow for a rapid spread of electric current and intercellular diffusion of second messengers and ions Christ, An erection is a complex event that results from vascular, neural, endocrine, and psychological input. Initially, parasympathetic branches of the sacral plexus cause dilation of the penile arteries.
These branches release acetylcholine, which stimulate the release of nitric oxide NO from both nitrergic nerves and the cavernosal endothelium. The result is smooth muscle relaxation and increased penile blood flow Dean and Lue, ; Rosen and Kostis, ;. Arterial dilation leads to increased blood flow, which causes expansion of the sinusoids and accumulation of blood in the penis.
This results in the engorgement of the corpora cavernosa, the glans, and, to a lesser extent, the corpora spongiosum. As the sinusoids continue to expand, venous plexuses become compressed, reducing venous flow and further trapping blood inside the penis. Finally, the ischiocavernosus and bulbocavernosus muscles contract, which compress the spongiosum and penile veins and cause further engorgement Wein et al. Sympathetic adrenergic nerves are responsible for detumescence of the erect penis and maintenance of the flaccid state.
Any disruption in this physiological process can lead to ED. The anatomical site felt to be the most common cause of erectile dysfunction in the general population is the neuromuscular junction where the NANC nerves meet the smooth muscle and vascular endothelium of the deep cavernous penile arteries. This is where nitric oxide and cGMP play a critical role in regulating penile blood flow [15].
The typical erectile dysfunction ED patient secretes less than the normal amount of NO into the neuromuscular junction.
Neurologic disease can produce discrete lesions in central or peripheral nerves which cause erectile dysfunction by altering upstream nerve function, or can alter NO production at the neuromuscular junction and vascular endothelium. Other causes of impotence include drug induced erectile dysfunction, endocrine disorders, vascular disease and venogenic erectile dysfunction. Thomas Mulligan, in Functional Neurobiology of Aging , The penis consists of three components, two dorso-lateral corpora cavernosa and a ventral corpus spongiosum which surrounds the penile urethra and distally forms the glans penis.
A thick fibrous sheath, the tunica albuginea, surrounds each of the corpora cavernosa, and all three corpora are bound together by Buck's fascia. The ischiocavernosus and bulbospongiosus muscles surround the proximal portions of the corpora cavernosa Williams and Warwick, Each corpus consists of smooth muscle bundles, elastic fibers, collagen, and loose fibrous tissue which form the trabeculae.
Between the trabeculae are blood-filled lacunar spaces which are lined by flat endothelial cells. The arterial supply to the penis is the internal pudendal arteries, which become the penile arteries. Each penile artery terminates in bulbar, urethral, dorsal, and cavernosal arteries. The paired cavernosal arteries penetrate the tunica albuginea and enter the crura of the corpora cavernosa.
Each ends in multiple twisted branches called helicine arteries that supply the lacunae. There may be two circulatory routes in the human corpora. One route goes from the cavernosal artery to capillary networks underlying the tunica albuginea with the capillaries serving as nutritional vessels.
This pathway is the main circulatory route during the flaccid state.
The second route is via anastomoses from the cavernosal artery through the helicine arteries to the cavernosa, which then empties into the postcavernous venules and serves as the main vascular pathway in the mechanism of erection. Venous return from the pendulous penis occurs through the deep and superficial dorsal veins of the penis.
Subtunical venules located between the periphery of the erectile tissue and the tunica albuginea drain the lacunar spaces. They coalesce to form emissary veins which penetrate the tunica albuginea and drain into the deep dorsal vein or the circumflex system. Drainage from the proximal crura is mainly through the cavernosal and crural veins.
Simon Podnar, David B. ED assessed prospectively with nocturnal tumescence studies before and after transurethral prostatectomy showed that ED occurred in none of the 40 men studied Soderdahl et al. Retrograde ejaculation, however, is not uncommon following transurethral prostatectomy, but is usually accepted by patients as a minor problem. The prospects are quite different for patients undergoing treatment for prostate cancer.
The two standard treatments for this are radiotherapy or radical prostatectomy; the latter involves removal of the prostatic capsule, to which the corporeal nerves are intimately bound. These travel outside and behind the prostatic capsule in the lateral pelvic fascia until nearer the apex of the prostate, where they lie just lateral to the urethra. It is at this point that they are particularly vulnerable to surgery. They then pass behind the penile artery and dorsal penile nerve to enter the corpora on each side.
In a group of patients after laparoscopic radical prostatectomy the median baseline IIEF-5 score of 22 changed to 13 at 24 months after surgery. Number of nerves spared and age were independent predictors of a return to baseline function Levinson et al. Cavernous nerve sparing during radical prostatectomy is not associated with worse cancer outcomes in appropriately selected patients. Unfavorable clinical factors, prostate biopsy characteristics, and poor baseline erectile function predict less cavernous nerve-sparing surgery Stember et al.
Cavernous nerve preservation during laparoscopic radical prostatectomy is not an all-or-none phenomenon. Partial nerve preservation may lead to an incremental improvement in the return of sexual function. Other independently predictive variables were patient age at surgery, months since surgery, and preoperative Sexual Health Inventory for Men Levinson et al.
During robot-assisted radical prostatectomy, avoidance of thermal injury produced nearly a fivefold improvement in early return of sexual function; otherwise dysfunction due to thermal injury largely recovered 2 years after the intervention.
Authors caution, however, about an uncritical increase in nerve volume preservation at the expense of positive surgical margins Ahlering et al. Preservation of just one nerve, in the majority of patients, results in similar potency recovery to that with two nerves preserved. Crossover innervation of the one nerve may be the underlying mechanism.
Male sexual functions involve the interactions of numerous organs, including the nervous system brain, spinal cord, peripheral nerves , the prostate gland, seminal vesicles, and testicles. The prostate has muscular and glandular components. Its major function is to secrete a slightly alkaline fluid which becomes part of the seminal fluid. Seminal vesicles are glands that lie behind the bladder and also release fluid for transport of sperm.
The scrotum holds and protects the testicles, which generate sperm and testosterone; testosterone is the androgenic hormone critical for both primary and secondary male sexual characteristics such as muscle development, voice deepening, and body hair. Testosterone is also the primary androgen that controls the functional activity of all male reproductive tract structures.
The process is under the control of parasympathetic fibres; the neurotransmitter involved is now known to be nitric oxide NO. Higher concentration of cytoplasmic calcium, via its release from intracellular stores sarcoplasmic reticulum and its entry from the extracellular milieu opening of L-type membrane calcium channels , causes smooth-muscle cell contraction. The epididymis is an elongated canal attached to the posterior aspect of the testes. Ability to experience arousal can be blunted by depression or anxiety. Non-enzymatic glycation of proteins has been reported to impair endothelium-dependent relaxation of aorta in rats. The formation of products of non-enzymatic glycosylation to produce advanced glycosylation end-products generates reactive oxygen species that impair NO bioactivity.
The epididymis is an elongated canal attached to the posterior aspect of the testes. The epididymis stores, matures, and transports spermatozoa into the vas deferens. The vas deferens also stores and transports sperm. The shaft of the penis contains the urethra, a single tube with two functions: The glans is a highly innervated area located at the tip of the penis. The penis is supplied by the internal pudendal arteries, which become the penile arteries. The cavernosal artery, a branch of the penile artery , supplies the lacunar spaces through multiple branches.
Blood-filled lacunar spaces are essential for erection. Venules, located between the erectile tissue, drain the lacunae. Venous return from the penis occurs by way of the deep and superficial dorsal veins of the penis. For Instructors Request Inspection Copy.
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It could be through conference attendance, group discussion or directed reading to name just a few examples. We provide a free online form to document your learning and a certificate for your records. Already read this title? Please accept our apologies for any inconvenience this may cause. If a cause is diagnosed, you can often begin treatment immediately.
Being honest with yourself, your partner, and your doctor can help you seek out a diagnosis and a remedy for your ED problems. Lifestyle changes can also help improve your overall health. These changes include losing weight and quitting smoking. Over time, these improvements can benefit your sexual health and performance. Before these more modern treatments, men relied on massage to ease their ED symptoms.
Before the introduction of prescription medicines, prostatic massage was the primary treatment for ED. Some men still use it today in combination with other treatments. Prostatic massage is thought to help men with ED by clearing the prostatic duct. Massage might also interrupt infections and eliminate blocked fluids. A few studies have found that men who get prostate massage for the symptoms of ED experience improvement. Unfortunately, these studies have been small. Even still, for some men, this alternative option may be helpful in addition to other forms of treatment.
Some doctors who specialize in ED or prostatitis treatment may have a practitioner on staff or have one they can recommend to you. Some doctors may even perform prostatic massage themselves. Make sure that the person you select is trained specifically for prostatic massage. Your health insurance may not cover this type of treatment unless a medical doctor performs it.
Before you begin the massage treatments, call your health insurance company and request coverage verification. Ask the massage practitioner to do the same.