How The Penis Works The penis is just a collection of specialized blood vessels within a tough outer sheath of connective tissue. Sexual arousal causes blood to flow into the penis by releasing NO (Nitric Oxide) from the nerves supplying the penile arteries. The blood then fills a series of blood sacks called sinusoids allowing the spongy tissue to become engorged. As the engorged tissue presses against the outer fibrous sheath, the veins normally allowing blood to freely drain from the penis become narrowed. This traps the blood in the penis and helps to maintain the erection. Continued sexual arousal keeps the penile arteries widely dilated, allowing the build-up of pressure within the circulation to keep the penis erect. Nitric Oxide (NO) produced in the tissue lining these arteries and sinusoids keeps the smooth muscle around them relaxed so that maximum distention and rigidity occurs. What Can be Done to Make the Penis Work Better? There are several important things that a man can do to improve his erectile function: First, he can use relaxation techniques to reduce the effects of stress which can reduce the flow of blood into the penis. Next, he can work with his partner to increase sexual arousal. A high level of arousal keeps the penile arteries widely dilated due to the release of NO from nerve endings supplying those arteries. Most importantly, he can optimize NO production by the nerves and the tissue lining the penile vessels by following the Ten Steps to Better Erections. What About Prescription Medications? The behavioral changes recommended in “The Ten Steps” may not always result in sufficient improvement in erectile function. Men and their partners should realize that it may take a few weeks to a month for the changes to have an effect and that these good effects will build up over time. After waiting a sufficient amount of time, and under the supervision of a qualified health care professional, one of the three prescription medicines for ED (Cialis, Levitra or Viagra) can be added, starting at a lower than usual dose. These drugs act to increase cyclic GMP by inhibiting the enzyme, phosphodiesterase 5, that normally breaks GMP down. All of these medications can cause side effects and rare serious complications. Recent studies have shown that they do actually increase NO production. It is possible that their use could improve overall blood vessel health in addition to teating ED.