Erection
The word erection (from the Latin erectio) describes a stiffening and straightening of the organs containing a corpus cavernosum caused by blood stasis. In everyday life, the word erection mainly refers to the stiffening of the male penis. This usually occurs spontaneously or as a result of mechanical or psychological stimuli, especially during sexual arousal. Erections are the prerequisite for sex because without an erection, sexual intercourse in the conventional sense is not possible. When the female genital organs, mainly the clitoris, swell, this is also called an erection. However, the female erection is not absolutely necessary to have sex.
A male erection is usually caused by the erection centre in the lower spinal cord during sexual arousal. However, an erection can also be triggered by mechanical stimulation of the testicles and the penis. As a rule, it is the psyche that is responsible for erections: sexual arousal is mainly caused by erotic ideas, dreams, or perceptions. Likewise, optical stimuli or smells can lead to stiffening of the member. The difference in length between the normal state and the erect member varies from man to man. On average, one can assume a two- to four-fold expansion in length and a thickening by one and a half to three times.
As already briefly mentioned, an erect penis is necessary for a man to penetrate a woman. Penetration of the woman's vagina is in turn relevant for reproduction. However, fertilisation can occur without erection and vaginal intercourse under special circumstances.
Lay people often confuse erectile capacity with the colloquial manhood. Thus, potency is often even equated with reproductive capacity. In general, the quality of an erection is also regarded as a sign of youthfulness or vitality. However, foetuses in the womb are already capable of erections, as are babies. In healthy men, the erectile tissue functions well into old age and erections usually occur throughout life. This happens particularly often during sleep, during the so-called REM phases. This is why men often wake up with an erection in the morning. Orgasms with or without ejaculation also occur during sleep (wet dreams), but they are not always preceded by erections. Even the dead can, in rare cases, have a stiffening of the penis called a post-mortem erection due to passive blood stasis.
The mechanism behind an erection in men is as follows: The erectile tissue in the member fills with blood, and the so-called blocking arteries prevent this blood from flowing back immediately. A muscle called the ischiocavernosus muscle additionally strengthens the erection in the final stiffening phase. It exerts compression on the base of the corpora cavernosa, which subsequently maintains the greatly increased blood pressure within the corpora cavernosa. The muscle thus inhibits venous blood return by means of compression work so that an erection can be maintained even for several hours. In addition to certain sensual perceptions or stimuli, the body's own very complex processes also play a major role in penile and clitoral erections.