There is a bit of mystery that surrounds the average erection: Where did it come from? How long will it last? Will it be good enough? They happen when you least expect it (whilst asleep, or in math class). And they happen when you do expect it–hopefully. Biologically, men have less control then they think regarding when or how long they occur. In fact, normal men have at least 3 erections lasting 1 hour every night, while they are asleep, deep asleep. This is the penis “sighing” and relaxing, as it takes more energy to keep a penis flaccid than erect. Believe it or not.
The key to an erection lies within the male brain, through visual, auditory, or imagined stimuli, or through manual stimulation. Upon stimulation, the arteries within the penis relax, and blood flows into the penis at more than 20 times the normal rate. The spongy areas of the penis become firm and engorged with blood, much like filling up a balloon with air. So now that the penis is holding more blood, the veins, which usually drain the penis of blood, are compressed tightly enough that blood cannot exit the penis, in effect tying a knot in the balloon. And now the balloon is ready to go.
Erections last, on average, between fifteen and thirty minutes, and can cause the penis to rise to a fairly stiff angle. They can also curve upward or downward, to the right or to the left. This is why upscale clothiers in London ask men who are ordering custom tailored suits: “To what side do you dress, sir?” Right before ejaculation, a reflex is triggered (bulbocavernosus) which causes the muscles that surround the penis to forcefully compress the penis, such that the blood pressure within the penis reaches levels far higher than normal blood pressure. The penis falls when there are no more energy molecules available, in effect “running out of gas”. Viagra and other erectile drugs work by supplying more “gas” to the penis. Erections also fall from nervous system discharge during ejaculation. This discharge results in a latency period or “down time” during which it is difficult to achieve another erection. Once the nervous system has recovered, then an erection is again possible.
One can see what might cause the balloon to wilt (erectile dysfunction). There could be a problem with circulation (not enough pressure), a problem with venous leakage (the balloon has a hole in it) or nerve damage or hormonal issues (no one is blowing up the balloon) which could inhibit penile filling or emptying or the ability to feel sexual stimulation. Drugs, toxins, and conditions such as heart disease and diabetes are all culprits. This is why good health is so important for a healthy sex life.
You may never have ultimate control over something so willful as an erection, but it may be helpful to understand how it occurs. Because, with a finer understanding, hopefully, comes finer appreciation and enjoyment.