An erection occurs when the soft spongy tissue in the shaft of a man's penis fills with blood, causing the penis to enlarge and stiffen.

Spongy spaces (technically known as corpora cavernosa and corpora spongiosa) along the length of the penis fill with blood in response to physical stimulation, psychological stimulation, or both. This process requires that the blood supply and the nerve connections to the penis are working properly.

Dilation of the arteries that feed blood to the penis results in engorgement of the spongy tissue. Simultaneous contraction of the muscles at the base of the penis prevents the blood from draining out through the veins, thus maintaining the erection.

Nerves in the spinal cord also control erection, which receive input from physical contact to the penis and/or surrounding areas, sexual thoughts, dreams, or images, and sex hormones.

Barring an erectile disease, and provided there is sufficient blood flow and nerve impulses, a man is capable of getting an erection when sexually stimulated. It is important to know that erections come and go. The ability of a man to get an erection is an automatic, normal function similar to his ability to breathe and blink his eyes.

A Normal Part of Aging
An erection can take place in as little as several seconds or it can occur gradually over a longer period of time. In the later years of a man's life, beginning in the 50's and increasingly in the 60's and 70's, it can sometimes take longer to achieve an erection even with direct stimulation and a man may notice that his erection is not as firm as when he was a teenager. This is a normal part of aging, but causes some men distress because they measure their maleness or ability to please a partner by the firmness and speed with which they become erect.

However, the older man has some advantages over the younger one because his ejaculatory control is usually greater, therefore he can maintain an erection for a considerably longer period of time without feeling the ejaculatory urgency common in younger men. This advantage may be lost in men who have prostate problems because they often experience leakage of the blood supply required to maintain an erection, and can have weaker ejaculations.

B>Penis Size Not Related to Pleasure
Men of all ages occasionally have concerns about the size of their erect penis and whether it is sexually adequate. Although a common worry, the size of a man's erection is not related to his ability to please a partner or enjoy sex himself.

In fact, continually thinking about penis size can interfere with achieving an erection, and with the giving and receiving of pleasure.

There is rarely a relationship between the size of a flaccid penis and its size when erect. A small flaccid penis can show a remarkable change as it erects and a large flaccid penis sometimes changes very little in length or thickness, as it becomes erect. An erect penis is typically between five and seven inches long with a diameter between 1.25 and 1.5 inches. Of course there are variations in this range, which allow for some larger and some smaller penises.

It is not uncommon for a man's penis to curve a bit when it is erect. The degree of the curve varies from man to man, but it generally causes no discomfort or interference with sexual activity.

Peyronie's Disease
A very pronounced curve occurs in a condition called Peyronie's disease. Although it is not certain, it is thought to be caused by the development of hard, fibrous, inflamed tissue in the shaft of the penis, and usually starts as pain during erection, caused by stretching of inflamed penile tissue.

As the disease progresses, the pain subsides, and then fibrous tissue develops, causing the penis to curve to the left, right, or upward. The majority of cases of Peyronie's disease require medical attention and are generally curable.

Another erectile disorder, priapism, is the continual and pathological erection of the penis. It is usually caused by nonsexual factors such as spinal cord disease, leukemia or sickle cell disease, and, according to some reports, with the use of cocaine. Sometimes it happens for no known reason.

In cases of priapism, the increased blood flow that causes an erection is unable to drain from the penis in the usual way because the release mechanism has been broken down by the disease or affected by drugs or other unknown factors. It is extremely painful and may require surgery if the problem does not respond to medical treatment. Certain non-medical circumstances, such as painful stimulation of the penis, or disturbed emotional states such as fear, anger, guilt, anxiety, or shame can cause a man to lose his erection or prevent him from getting an erection in the first place. Emotional difficulties and the anticipation and worry about possibly losing an erection are common causes of a man's erectile difficulties.

Hope for Erectile Problems
If a man repeatedly experiences difficulty achieving or maintaining erections, he should not despair. In the last ten years much has been learned about treating erectile problems. The first step is to contact a competent urologist who can perform the necessary diagnostic tests to determine if medical factors are contributing to the problem.

In addition to a thorough urological evaluation, the man and his partner should consult a psychotherapist who specializes in sexual therapy.

Regardless of the origins of the erectile problem (medical, psychological, or in some cases both), as with any change in normal functioning, there can be an emotional impact on the man and his partner. Through counseling, the unspoken fears and misunderstandings of both partners can be explored, resulting in improved self-esteem and better communication.